WO2025218557A1 - Geometry reconstruction method and apparatus, and device - Google Patents

Abstract

The present application belongs to the technical field of communications. Disclosed are a geometry reconstruction method and apparatus, and a device. The geometry reconstruction method comprises: a decoding end decoding a first bitstream to obtain a first flag, wherein the first flag is used for indicating distribution information of original point clouds in a geometric structure corresponding to a Trisoup node; the decoding end processing vertices in the geometric structure on the basis of the first flag; and the decoding end using the processed vertices to reconstruct a point cloud.

Description

Geometric reconstruction method, device and equipment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202410464478.3 filed in China on April 17, 2024, the entire contents of which are incorporated herein by reference.

Technical Field

The present application belongs to the field of communication technology, and specifically relates to a geometric reconstruction method, device and equipment.

Background Art

In the geometry-based point cloud compression (G-PCC) encoder framework, the geometric and attribute information of a point cloud are encoded separately. Two methods exist for encoding geometric information: multitree-based geometry encoding and prediction tree-based geometry encoding. Among these multitree-based geometry encoding methods, the Trisoup geometry encoding algorithm has demonstrated superior compression performance.

In the Trisoup geometric coding algorithm in related technologies, in order to save code streams, vertices on edges that are shared multiple times between nodes are only encoded with one identification information and 2 bits of position information. This approach ignores the differences in point cloud distribution between nodes. Especially when the nodes are large, the point cloud distribution within the nodes is uneven. For example, there is no original point cloud around some vertices, so not all vertices are suitable for point cloud reconstruction. If the point cloud reconstruction method in related technologies is still used, it is likely to cause significant distortion of the reconstructed point cloud.

Summary of the Invention

The embodiments of the present application provide a geometric reconstruction method, apparatus, and device that can solve the problem of large distortion in reconstructed point clouds.

In a first aspect, a geometric reconstruction method is provided, which is performed by a decoding end and includes:

The decoding end decodes the first code stream to obtain a first flag, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a triangle soup (Trisoup) node;

The decoding end processes the vertices in the geometric structure according to the first flag;

The decoding end reconstructs the point cloud using the processed vertices.

In a second aspect, a geometric reconstruction method is provided, which is performed by an encoding end and includes:

The encoding end encodes the first flag to obtain a first code stream, where the first flag is used to indicate original point cloud distribution information in the geometric structure corresponding to the Trisoup node;

The encoding end processes the vertices in the geometric structure according to the first flag;

The encoder reconstructs the point cloud using the processed vertices.

In a third aspect, a geometric reconstruction device is provided, which is applied to a decoding end, and the device includes:

A first decoding module is configured to decode the first code stream to obtain a first flag, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node;

a first processing module, configured to process vertices in the geometric structure according to the first flag;

The second processing module is used to reconstruct the point cloud using the processed vertices.

In a fourth aspect, a geometric reconstruction device is provided, which is applied to an encoding end, and the device includes:

A first encoding module, configured to encode a first flag to obtain a first code stream, wherein the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node;

a third processing module, configured to process vertices in the geometric structure according to the first flag;

The fourth processing module is used to reconstruct the point cloud using the processed vertices.

In a fifth aspect, an electronic device is provided, which terminal includes a processor and a memory, wherein the memory stores programs or instructions that can be run on the processor, and when the program or instructions are executed by the processor, the steps of the method described in the first aspect are implemented, or the steps of the method described in the second aspect are implemented.

In a sixth aspect, an electronic device is provided, comprising a processor and a communication interface, wherein the processor is used to: decode a first code stream to obtain a first flag, the first flag being used to indicate the original point cloud distribution information in the geometric structure corresponding to the Trisoup node; process the vertices in the geometric structure according to the first flag; and reconstruct the point cloud using the processed vertices; or, the processor is used to: encode the first flag to obtain a first code stream, the first flag being used to indicate the original point cloud distribution information in the geometric structure corresponding to the Trisoup node; process the vertices in the geometric structure according to the first flag; and reconstruct the point cloud using the processed vertices.

In a seventh aspect, an electronic device is provided, comprising: a memory configured to store video data, and a processing circuit configured to implement the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect.

In an eighth aspect, a readable storage medium is provided, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the method described in the first aspect are implemented, or the steps of the method described in the second aspect are implemented.

In the ninth aspect, a coding and decoding system is provided, comprising: a coding end device and a decoding end device, wherein the coding end device can be used to execute the steps of the method described in the second aspect, and the decoding end device can be used to execute the steps of the method described in the first aspect.

In the tenth aspect, a chip is provided, which includes a processor and a communication interface, the communication interface and the processor are coupled, and the processor is used to run programs or instructions to implement the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect.

In the eleventh aspect, a computer program/program product is provided, which is stored in a storage medium and is executed by at least one processor to implement the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect.

In a twelfth aspect, a computer program product is provided, comprising computer instructions, which, when executed by a processor, implement the steps of the method described in the first aspect, or implement the steps of the method described in the second aspect.

In the embodiment of the present application, the decoding end decodes and obtains a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a coding and decoding system provided in an embodiment of the present application;

FIG2 a is a flowchart of encoding performed by an encoder based on an AVS-PCC encoding framework;

FIG2 b is a flowchart of encoding performed by an encoder based on the MPEG G-PCC encoding framework;

FIG3 a is a flowchart of decoding performed by a decoder based on the AVS-PCC decoding framework;

FIG3 b is a flowchart of decoding performed by a decoder based on the MPEG G-PCC decoding framework;

FIG4 is a schematic diagram of a flow chart of a geometric reconstruction method according to an embodiment of the present application;

FIG5 is a schematic diagram of a reconstructed surface according to an embodiment of the present application;

FIG6 is a schematic diagram of the geometric structure corresponding to the Trisoup node;

FIG7 is a schematic flow chart of a decoding process according to an embodiment of the present application;

FIG8 is a second flow chart of the geometric reconstruction method according to an embodiment of the present application;

FIG9 is a schematic flow chart of the encoding process according to an embodiment of the present application;

FIG10 is a schematic diagram of a structure of a geometric reconstruction device according to an embodiment of the present application;

FIG11 is a second structural diagram of the geometric reconstruction device according to an embodiment of the present application;

FIG12 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

FIG13 is a schematic structural diagram of a terminal according to an embodiment of the present application.

DETAILED DESCRIPTION

The following will be combined with the accompanying drawings in the embodiments of this application to clearly describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same type, and do not limit the number of objects, for example, the first object can be one or more. In addition, "or" in this application represents at least one of the connected objects. For example, "A or B" covers three options, namely, Option 1: including A but not including B; Option 2: including B but not including A; Option 3: including both A and B. The character "/" generally indicates that the objects associated before and after are in an "or" relationship.

Before introducing the technical solutions provided by the embodiments of the present application, the meanings of some of the terms are first introduced.

Point Cloud: A point cloud is a set of irregularly distributed discrete points in space that represent the spatial structure and surface properties of a 3D object or scene. Point clouds can be categorized into different types based on different classification criteria. For example, based on how the point cloud is acquired, they can be divided into dense point clouds and sparse point clouds. Based on the temporal nature of the point cloud, they can be divided into static point clouds and dynamic point clouds.

Point Cloud Data: The geometric coordinate information and attribute information of each point in the point cloud together constitute the point cloud data. Among them, the geometric coordinate information can also be called three-dimensional position information. The geometric coordinate information of a point in the point cloud refers to the spatial coordinates (x, y, z) of the point, which can include the coordinate values of the point in the directions of each coordinate axis of the three-dimensional coordinate system, for example, the coordinate value x in the X-axis direction, the coordinate value y in the Y-axis direction, and the coordinate value z in the Z-axis direction. The attribute information of a point in the point cloud can include at least one of the following: color information, material information, laser reflection intensity information (also called reflectivity). Usually, each point in the point cloud has the same amount of attribute information. For example, each point in the point cloud can have two kinds of attribute information: color information and laser reflection intensity. For another example, each point in the point cloud can have three kinds of attribute information: color information, material information, and laser reflection intensity information.

Point Cloud Compression (PCC): Point cloud coding refers to the process of encoding the geometric coordinate information and attribute information of each point in the point cloud to obtain a compressed code stream. Point cloud coding can include two main processes: geometric coordinate information encoding and attribute information encoding. Currently, the point cloud coding framework that can compress point clouds can be the geometry-based Point Cloud Compression (G-PCC) codec framework provided by the Moving Picture Experts Group (MPEG) or the video-based Point Cloud Compression (V-PCC) codec framework, or the AVS-PCC codec framework provided by the Audio Video Standard (AVS).

Point cloud decoding: Point cloud decoding refers to the process of decoding the compressed bitstream obtained from point cloud encoding to reconstruct the point cloud. Specifically, it refers to the process of reconstructing the geometric coordinate information and attribute information of each point in the point cloud based on the geometric bitstream and attribute bitstream in the compressed bitstream. After obtaining the compressed bitstream at the decoding end, the geometric bitstream is first entropy decoded to obtain the quantized information of each point in the point cloud, and then dequantized to reconstruct the geometric coordinate information of each point in the point cloud. For the attribute bitstream, entropy decoding is first performed to obtain the quantized attribute residual information or quantized transform coefficients of each point in the point cloud. The quantized attribute residual information is then dequantized to obtain the reconstructed residual information, and the quantized transform coefficients are dequantized to obtain the reconstructed transform coefficients. The reconstructed transform coefficients are then inversely transformed to obtain the reconstructed residual information. Based on the reconstructed residual information of each point in the point cloud, the attribute information of each point in the point cloud can be reconstructed. The reconstructed attribute information of each point in the point cloud is sequentially associated with the reconstructed geometric coordinate information to reconstruct the point cloud.

Figure 1 is a schematic diagram of a codec system 10 provided in an embodiment of the present application. The technical solution of the embodiment of the present application involves performing codec (including encoding or decoding) on point cloud data.

As shown in FIG1 , the codec system 10 includes a source device 100 that provides encoded point cloud data that is decoded and displayed by a destination device 110. Specifically, the source device 100 provides the point cloud data to the destination device 110 via a communication medium 120. The source device 100 and the destination device 110 may include any one or more of a desktop computer, a notebook (i.e., laptop) computer, a tablet computer, a set-top box, a mobile phone, a wearable device (e.g., a smart watch or a wearable camera), a television, a camera, a display device, an in-vehicle device, a virtual reality (VR) device, an augmented reality (AR) device, a mixed reality (MR) device, a digital media player, a video game console, a video conferencing device, a video streaming device, a broadcast receiver device, a broadcast transmitter device, a spacecraft, an aircraft, a robot, a satellite, and the like.

In the example of Figure 1, the source device 100 includes a data source 101, a memory 102, an encoder 200, and an output interface 104. The destination device 110 includes an input interface 111, a decoder 300, a memory 113, and a display device 114. The source device 100 represents an example of an encoding device, while the destination device 110 represents an example of a decoding device. In other examples, the source device 100 and the destination device 110 may not include some of the components in Figure 1, or may include other components other than Figure 1. For example, the source device 100 may obtain point cloud data through an external capture device. Similarly, the destination device 110 may be connected to an external display device interface without including an integrated display device. For another example, the memory 102 and the memory 113 may be external memories.

Although FIG1 illustrates source device 100 and destination device 110 as separate devices, in some examples, the two may be integrated into a single device. In such embodiments, the functions corresponding to source device 100 and the functions corresponding to destination device 110 may be implemented using the same hardware or software, or using separate hardware or software, or any combination thereof.

In some examples, source device 100 and destination device 110 can perform unidirectional data transmission or bidirectional data transmission. If bidirectional data transmission is performed, source device 100 and destination device 110 can operate in a substantially symmetrical manner, that is, each of source device 100 and destination device 110 includes an encoder and a decoder.

The data source 101 represents the source of point cloud data (i.e., raw, unencoded point cloud data) and provides the point cloud data to the encoder 200, and the encoder 103 encodes the point cloud data. The source device 100 may include a capture device (e.g., a camera device, a sensor device, or a scanning device), an archive of previously captured point cloud data, or a feed interface for receiving point cloud data from a data content provider. Among them, the camera device may include an ordinary camera, a stereo camera, and a light field camera, etc., the sensor device may include a laser device, a radar device, etc., and the scanning device may include a three-dimensional laser scanning device, etc. Point cloud data can be obtained by capturing a real-world visual scene through a capture device. Alternatively, the data source 101 may generate computer graphics-based data as source data, or combine real-time data, archived data, and computer-generated data. For example, the data source generates point cloud data based on a virtual object (e.g., a virtual three-dimensional object and a virtual three-dimensional scene obtained by three-dimensional modeling).

The encoder 200 encodes captured, pre-captured, or computer-generated data. The encoder 200 can rearrange the point cloud data from the order in which it was received (sometimes referred to as "display order") into an encoding order. The encoder 200 can generate a bitstream comprising the encoded point cloud data. The source device 100 can then output the encoded point cloud data to the communication medium 120 via the output interface 104 for receipt or retrieval by, for example, the input interface 111 of the destination device 110.

Memory 102 of source device 100 and memory 113 of destination device 110 represent general-purpose memories. In some examples, memory 102 may store raw data from data source 101, and memory 113 may store decoded point cloud data from decoder 300. Additionally or alternatively, memories 102 and 113 may store software instructions executable by, for example, encoder 200 and decoder 300, respectively. Although memory 102 and memory 113 are shown separately from encoder 200 and decoder 300 in this example, it should be understood that encoder 200 and decoder 300 may also include internal memory for functionally similar or equivalent purposes. If encoder 200 and decoder 300 are deployed on the same hardware device, memory 102 and memory 113 may be the same memory. Furthermore, memories 102 and 113 may store, for example, encoded point cloud data output from encoder 200 and input to decoder 300. In some examples, portions of memory 102 , 113 may be allocated as one or more point cloud buffers, eg, for storing raw, decoded, or encoded point cloud data.

In some examples, source device 100 can output the encoded data from output interface 104 to memory 113. Similarly, destination device 110 can access the encoded data from memory 113 via input interface 111. Memory 113 or storage 102 can include any of a variety of distributed or locally accessed data storage media, such as a hard drive, a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc Read-Only Memory (CD-ROM), flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded point cloud data.

The output interface 104 may include any type of medium or device capable of transmitting the encoded point cloud data from the source device 100 to the destination device 110. For example, the output interface 104 may include a transmitter or transceiver, such as an antenna, configured to transmit the encoded point cloud data directly from the source device 100 to the destination device 110 in real time. The encoded point cloud data may be modulated according to a communication standard of a wireless communication protocol and transmitted to the destination device 110.

The communication medium 120 may include a transient medium such as a wireless broadcast or a wired network transmission. For example, the communication medium 120 may include a radio frequency (RF) spectrum or one or more physical transmission lines (e.g., cables). The communication medium 120 may form part of a packet-based network such as a local area network, a wide area network, or a global network such as the Internet. The communication medium 120 may also take the form of a storage medium (e.g., a non-transitory storage medium) such as a hard disk, a flash drive, a compact disk, a digital point cloud disk, a Blu-ray disc, a volatile or non-volatile memory, or any other suitable digital storage medium for storing the encoded point cloud data.

In some embodiments, the communication medium 120 may include a router, a switch, a base station, or any other device that can be used to facilitate communication from the source device 100 to the destination device 110. For example, a server (not shown) can receive the encoded point cloud data from the source device 100 and provide it to the destination device 110, for example, by transmitting it to the destination device 110 via a network. The server may include, for example, a web server (for a website), a server configured to provide file transfer protocol services (such as File Transfer Protocol (FTP) or File Delivery Over Unidirectional Transport (FLUTE) protocol), a content delivery network (CDN) device, a Hypertext Transfer Protocol (HTTP) server, a Multimedia Broadcast Multicast Services (MBMS) or an evolved Multimedia Broadcast Multicast Service (eMBMS) server, or a network-attached storage (NAS) device, etc. The server can implement one or more HTTP streaming protocols, such as MPEG Media Transport (MMT) protocol, Dynamic Adaptive Streaming over HTTP (DASH) protocol, HTTP Live Streaming (HLS) protocol or Real Time Streaming Protocol (RTSP).

The destination device 110 can access the encoded point cloud data from the server, for example, via a wireless channel (e.g., a Wi-Fi connection) or a wired connection (e.g., a digital subscriber line (DSL), a cable modem, etc.) for accessing the encoded point cloud data stored on the server.

The output interface 104 and the input interface 111 may represent a wireless transmitter/receiver, a modem, a wired networking component (e.g., an Ethernet card), a wireless communication component operating according to the IEEE 802.11 standard or the IEEE 802.15 standard (e.g., ZigBee™), the Bluetooth standard, or other physical components. In examples where the output interface 104 and the input interface 111 include wireless components, the output interface 104 and the input interface 111 may be configured to transmit data, such as encoded point cloud data, according to WIFI, Ethernet, a cellular network (such as 4th Generation (4G), Long Term Evolution (LTE), Advanced LTE, 5th Generation (5G), 6th Generation (6G)), etc.).

The technology provided in the embodiments of the present application can be applied to support one or more application scenarios such as: machine perception of point cloud, which can be used in scenarios such as autonomous navigation systems, real-time inspection systems, geographic information systems, visual sorting robots, emergency rescue robots, etc.; human eye perception of point cloud, which can be used in point cloud application scenarios such as digital cultural heritage, free viewpoint broadcasting, three-dimensional immersive communication, and three-dimensional immersive interaction.

Input interface 111 of destination device 110 receives an encoded bitstream from communication medium 120. The encoded bitstream may include high-level syntax elements and encoded data units (e.g., sequences, groups of pictures, pictures, slices, blocks, etc.), wherein the high-level syntax elements are used to decode the encoded data units to obtain decoded point cloud data. Display device 114 displays the decoded point cloud data to a user. Display device 114 may include a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light-emitting diode (OLED) display, or other types of display devices. In some examples, destination device 110 may not have display device 114. For example, if the decoded point cloud data is used to determine the position of a physical object, display device 114 may be replaced by a processor.

The encoder 200 and the decoder 300 may be implemented as one or more of a variety of processing circuits, which may include a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), discrete logic, hardware, or any combination thereof. When the technology is implemented in whole or in part in software, the device may store instructions for the software in an appropriate non-transitory computer-readable storage medium and use one or more processors to execute the instructions in hardware to perform the technology provided in the embodiments of the present application.

The following describes the basic principles of the encoder 200 and decoder 300 provided in the embodiments of the present application, taking the G-PCC and AVS-PCC codec frameworks as examples.

The encoding and decoding frameworks of G-PCC and AVS-PCC are roughly the same. Figure 2a shows a coding flow chart executed by an encoder based on the AVS-PCC coding framework, and Figure 2b shows a coding flow chart executed by an encoder based on the MPEG G-PCC coding framework. The above encoders may be encoder 200 shown in Figure 1. Both of these coding frameworks can be roughly divided into a geometric coordinate information encoding process and an attribute information encoding process. In the geometric information encoding process, the geometric coordinate information of each point in the point cloud is encoded to obtain a geometric bitstream; in the attribute information encoding process, the attribute information of each point in the point cloud is encoded to obtain an attribute bitstream; the geometric bitstream and the attribute bitstream together constitute the compressed bitstream of the point cloud.

For the geometric information encoding process, the encoding process performed by the encoder 200 is as follows:

1. Pre-processing: This may include coordinate transformation and voxelization. Pre-processing converts point cloud data in three-dimensional space into integer form through scaling and translation operations, and moves its minimum geometric position to the coordinate origin. In some examples, encoder 200 may not perform pre-processing.

2. Geometric coding: For the AVS-PCC coding framework, geometric coding includes two modes, namely, geometric coding based on multi-tree (Octree) and geometric coding based on prediction tree. For the G-PCC coding framework, geometric coding includes three modes, namely, geometric coding based on multi-tree, geometric coding based on trisoup, and prediction coding based on prediction tree. Among them:

Multitree-based geometric coding, such as octree-based geometric coding: An octree is a tree-like data structure that evenly divides a predefined bounding box in three-dimensional space, with each node having eight children. By indicating whether each child node in the octree is occupied using "1" or "0", occupancy codes are generated as the code stream of point cloud geometric information.

Geometric coding based on prediction tree: A prediction strategy is used to generate a prediction tree, and each node is traversed from the root node of the prediction tree, and the residual coordinate value corresponding to each traversed node is encoded.

Triangle-based geometric encoding: Divide the point cloud into blocks of a certain size and locate the intersection points (called vertices) of the point cloud surface at the edges of the blocks. The geometric information is compressed by encoding whether each edge on the block has an intersection and the location of the intersection point.

3. Geometry Entropy Encoding: Statistical compression encoding is performed on the occupancy code information of the multi-branch tree, the prediction residual information of the prediction tree, and the vertex information of the triangle representation, and the final output is a binary (0 or 1) compressed code stream. Statistical coding is a lossless coding method that can effectively reduce the bit rate required to express the same signal. A commonly used statistical coding method is context-based binary arithmetic coding (CABAC).

4. Geometric reconstruction: Decode and reconstruct the geometric information after geometric encoding.

For the attribute information encoding process, the encoding process performed by the encoder 200 is as follows:

1. Color transformation: Apply a transformation to transform the color information of an attribute to a different domain. For example, the color information can be transformed from the RGB color space to the YCbCr color space.

2. Attribute Recoloring: In lossy encoding, after encoding the geometric coordinates, the encoder needs to decode and reconstruct the geometry, restoring the geometry of each point in the point cloud. The attribute information of one or more neighboring points in the original point cloud is searched for and used as the attribute information for the reconstructed point.

In some examples, encoder 200 may not perform color conversion or attribute recoloring.

3. Attribute information processing: In AVS-PCC, attribute information processing can include three modes, namely prediction coding, transform coding, and prediction and transform coding. These three coding modes can be used under different conditions.

Predictive coding involves determining neighboring points of the point to be coded from among the coded points based on information such as distance or spatial relationships, and then calculating predicted attribute information for the point to be coded based on the attribute information of the predicted points, based on a set criterion. The difference between the actual attribute information of the point to be coded and the predicted attribute information is calculated as the attribute residual information, which is then quantized, transformed (optionally), and entropy coded.

Transform coding refers to the use of transformation methods such as Discrete Cosine Transform (DCT) and Haar Transform (Haar) to group and transform attribute information and quantize the transform coefficients; through inverse quantization and inverse transformation, attribute reconstruction information is obtained; the difference between the real attribute information and the attribute reconstruction information is calculated to obtain attribute residual information and quantize it; and the quantized transform coefficients and attribute residuals are entropy coded.

Predictive transform coding refers to using the attribute residual information obtained by prediction to perform transformation, quantize the transform coefficients, and perform entropy coding.

In MPEG G-PCC, attribute information processing can include three modes, namely Prediction Transform coding, Lifting Transform coding, and Region Adaptive Hierarchical Transform (RAHT) coding. These three coding modes can be used under different conditions.

Predictive transform coding involves dividing the point cloud into multiple levels of detail (LoDs) by selecting subsets of points based on distance, achieving a multi-level point cloud representation from coarse to fine quality. Adjacent layers can be predicted from the bottom up, where neighboring points in the coarse layer predict the attributes of points introduced in the fine layer, obtaining the corresponding attribute residual information. The points in the lowest layer are encoded as reference information.

Lifting transform coding refers to introducing a weight update strategy for neighborhood points based on the prediction of adjacent layers of LoD, ultimately obtaining the predicted attribute information of each point and the corresponding attribute residual information.

Hierarchical region adaptive transform coding means that the attribute information is transformed into a transform domain through RAHT transformation, which is called transform coefficient.

4. Attribute Quantization: The degree of quantization is usually determined by the quantization parameter. The transform coefficients or attribute residual information obtained by attribute information processing are quantized and entropy coded. For example, in predictive transform coding and lifting transform coding, entropy coding is performed on the quantized attribute residual information; in RAHT, entropy coding is performed on the quantized transform coefficients.

5. Entropy Coding: Run-length coding and arithmetic coding are typically used to achieve final compression of quantized attribute residual information and/or transform coefficients. The corresponding coding mode, quantization parameters, and other information are also encoded using an entropy encoder.

The encoder 200 encodes the geometric coordinate information of each point in the point cloud to obtain a geometry bitstream, and encodes the attribute information of each point in the point cloud to obtain an attribute bitstream. The encoder 200 can transmit the encoded geometry bitstream and attribute bitstream together to the decoder 300.

FIG3a shows a decoding flowchart performed by a decoder based on the AVS-PCC decoding framework, and FIG3b shows a decoding flowchart performed by a decoder based on the MPEG G-PCC decoding framework. The decoder may be decoder 300 shown in FIG1 . After receiving the compressed code stream (i.e., the attribute bit stream and the geometry bit stream) transmitted by encoder 200, decoder 300 decodes the geometry bit stream to reconstruct the geometric coordinate information of each point in the point cloud, and decodes the attribute bit stream to reconstruct the attribute information of each point in the point cloud.

The decoding process performed by the decoder 300 is as follows:

1. Entropy Decoding: Entropy decoding is performed on the geometry bit stream and attribute bit stream respectively to obtain the geometry syntax elements and attribute syntax elements.

2. Geometric decoding: For the AVS-PCC coding framework, geometric decoding includes two modes: octree-based geometric decoding and prediction tree-based geometric decoding. For the G-PCC coding framework, geometric coding includes three modes: octree-based geometric decoding, trisoup-based geometric decoding, and prediction tree-based prediction decoding.

Multitree-based geometry decoding, such as octree-based geometry decoding: an octree is reconstructed based on geometry syntax elements parsed from a geometry bitstream.

Prediction tree-based geometry decoding: The prediction tree is reconstructed based on the geometry syntax elements parsed from the geometry bitstream.

Geometry decoding based on triangle representation: reconstructs the triangle model based on the geometry syntax elements parsed from the geometry bitstream.

3. Geometric reconstruction: Perform reconstruction to obtain the geometric coordinate information of the points in the point cloud.

4. Coordinate inverse transformation: Perform inverse transformation on the reconstructed geometric coordinate information to convert the reconstructed coordinates (positions) of the points in the point cloud from the transformed domain back to the initial domain.

5. Dequantization: Dequantize the attribute syntax elements.

6. Attribute information processing: In AVS-PCC, attribute information processing determines the color information of the midpoint in the point cloud by predicting or transforming the inverse quantized prediction residual or prediction residual transformation coefficient, or by transforming the inverse quantized transformation coefficient to determine the color information of the midpoint in the point cloud.

In MPEG G-PCC, attribute information processing determines the color information of the point in the point cloud by using RAHT to inversely quantize the attribute information, or by using LOD and inverse lifting to determine the color information of the point in the point cloud.

7. Color inversion: Convert the color information from the YCbCr color space to the RGB color space. In some examples, the color inversion operation may not be performed.

As shown in FIG4 , the present application provides a geometric reconstruction method, which is performed by a decoding end. The method includes:

Step 401: The decoding end decodes the first code stream to obtain a first flag, where the first flag is used to indicate the original point cloud distribution information in the geometric structure corresponding to the Trisoup node; the original point cloud refers to the point cloud before the point cloud is reconstructed; and the original point cloud distribution information refers to the point cloud distribution in the geometric structure before the point cloud is reconstructed.

Step 402: The decoding end processes the vertices in the geometric structure according to the first flag;

Step 403: The decoding end reconstructs the point cloud using the processed vertices.

In this embodiment, a Trisoup node refers to a multi-branch tree node. Trisoup conceptualizes the geometric shape of the point cloud within each node as a surface that intersects the edge of each geometric body at most once. The points that intersect the edge of the geometric body are called vertices. These vertices are shared between adjacent nodes, ensuring the continuity of the reconstructed surface between nodes. The existence of a vertex on the edge of the geometric body corresponding to each node and the quantized position of the vertex on the edge can be represented as 1 bit and 2 bits, respectively. Inside the geometric body corresponding to each node, the reconstructed surface is composed of non-planar polygons formed by these vertices, as shown in Figure 5, organized as a set of triangles.

Optionally, the decoding end can determine the neighbor information of each edge of the geometric structure corresponding to the Trisoup node, and the neighbor information can be used as context for subsequent entropy decoding. The neighbor information includes point cloud occupancy information of adjacent edges.

The decoding end may use the neighbor information to decode a vertex existence flag and a quantized vertex position of each edge of the geometric structure, wherein the quantized vertex position exists when the vertex existence flag indicates that a vertex exists.

The encoding end obtains a first flag based on the occupancy information of the eight sub-geometric bodies and the vertex existence flag obtained from a Trisoup node. The first flag is used to represent the original point cloud distribution information of the Trisoup node. The encoding end encodes the first flag to generate a first code stream and sends it to the decoding end. The decoding end decodes the first flag to obtain the original point cloud distribution information; the decoding end determines the qualifications of the vertices in the Trisoup node based on the first flag obtained by decoding. For example, the decoding end determines reasonable vertices (which can be used for point cloud reconstruction), unreasonable vertices (not suitable for point cloud reconstruction, such as there is no original point cloud in the first range around the vertex), and relatively reasonable vertices (such as there is no original point cloud in the second range around the vertex or the original point cloud is small, such as less than a threshold), etc., based on the first flag, and deletes or corrects the vertices according to the judgment result. Optionally, when the decoding end determines that the vertex is a reasonable vertex, it does not process the reasonable vertex. After processing the vertex, the decoding end uses the processed vertex to reconstruct the point cloud.

Optionally, the first mark may include one or more flags, that is, the encoding end may determine one or more flags for indicating the distribution of the original point cloud and encode the one or more flags. The decoding end may obtain one or more flags by decoding. The one or more flags included in the first mark may be flags corresponding to different axes. For example, the first mark includes mark 1, mark 2, and mark 3, wherein mark 2 may include mark 2 corresponding to the three axes of x, y, and z, respectively, and mark 3 may include mark 3 corresponding to the three axes of x, y, and z, respectively.

In an embodiment of the present application, a decoding end decodes and obtains a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed, and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

As an optional embodiment, the method further includes:

Determine the context based on the vertex distribution information in the geometric structure corresponding to the Trisoup node;

The decoding of the first code stream to obtain the first flag includes:

The first code stream is decoded according to the context to obtain a first flag.

In this embodiment, the decoding end may further determine a context according to the distribution of vertices in the Trisoup node, and decode the first code stream using the context to obtain the first flag.

Optionally, the context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes.

In this embodiment, the target axis can be any of the three axes: x, y, and z. If the first flag includes multiple flags, the context can include contexts corresponding to the multiple flags. For example, if the first flag includes flag 1, flag 2, and flag 3, the context can include the context of flag 2 and the context of flag 3.

When decoding the first flag at the decoding end, the context corresponding to the axis to be decoded is used. For example, when decoding flag 2 corresponding to the x-axis, the context corresponding to the x-axis is used, that is, whether the ratio of the number of vertices in the first area along the x-axis to the total number of vertices is greater than or equal to the first threshold; when decoding flag 2 corresponding to the y-axis, the context corresponding to the y-axis is used, that is, whether the ratio of the number of vertices in the first area along the y-axis to the total number of vertices is greater than or equal to the first threshold; when decoding flag 3 corresponding to the z-axis, the context corresponding to the z-axis is used, that is, whether the ratio of the number of vertices in the first area along the z-axis to the total number of vertices is greater than or equal to the first threshold.

Optionally, the first area may be a preset range of the target area, and the first area may be recorded as the negative semi-axis or the positive semi-axis. For example, if the distance between the target axial dimension value of the vertex coordinate and the target axial dimension value of the starting point of the edge where the vertex is located is less than a first predetermined threshold, the vertex is considered to be located on the negative semi-axis of the target axial direction. In this case, the ratio of the number of vertices in the first area of the target axial direction to the total number of vertices is: the ratio of the number of vertices in the negative semi-axis of the target axial direction to the total number of vertices. If the distance between the target axial dimension value of the vertex coordinate and the target axial dimension value of the end point of the edge where the vertex is located is less than a second predetermined threshold, the vertex is considered to be located on the positive semi-axis of the target axial direction. In this case, the ratio of the number of vertices in the first area of the target axial direction to the total number of vertices is: the ratio of the number of vertices in the positive semi-axis of the target axial direction to the total number of vertices.

When the first area is the negative semi-axis or the positive semi-axis of the target axis, the first threshold indicated in the context may be different, for example: the context indicates whether the ratio of the number of vertices in the negative semi-axis of the target axis to the total number of vertices is greater than th1, or the context indicates whether the ratio of the number of vertices in the positive semi-axis of the target axis to the total number of vertices is greater than th2, and th1 and th2 may be different.

When the decoding end obtains the first flag according to the context decoding, the context of the target axis corresponding to the first flag to be decoded is used. For example, if the decoding end decodes flag 2 corresponding to the x-axis, the flag 2 is decoded based on whether the ratio of the number of vertices in the first region along the x-axis to the total number of vertices is greater than or equal to a first threshold; if the decoding end decodes flag 3 corresponding to the y-axis, the flag 3 is decoded based on whether the ratio of the number of vertices in the first region along the y-axis to the total number of vertices is greater than or equal to the first threshold. Decoding flags for other axes is similar to the above examples and is not listed here one by one.

As an optional embodiment, the first flag includes at least one of the following:

(1) Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected; Flag 1 can be denoted as nodeflag, which is used to indicate whether there are vertices in the geometric structure corresponding to the Trisoup node that need to be processed. For example, nodeflag = 1 indicates that there are vertices in the geometric structure that need to be processed, and nodeflag = 0 indicates that there are no vertices in the geometric structure that need to be processed. It should be noted that when nodeflag indicates that there are no vertices in the geometric structure that need to be processed, the first flag does not include flags 2 and 3.

(2) Flag 2: used to indicate whether it is necessary to correct the dimension value of the vertex in the target axis, and the target axis is any of the three axes; the flag 2 can be recorded as axiFlag, and axiFlag is used to indicate based on which circumferential axis the dimension value of the vertex needs to be corrected, for example: axiFlag can include axiFlag_1, axiFlag_2, axiFlag_3, axiFlag_1, axiFlag-_2, axiFlag_3 correspond to the x-axis, y-axis, and z-axis respectively, and the correspondence between the two is not limited here. For example: axiFlag_1 can be used to indicate whether it is necessary to correct the dimension value of the vertex in the x-axis (or y-axis or z-axis); axiFlag_2 can be used to indicate whether it is necessary to correct the dimension value of the vertex in the y-axis (or z-axis or x-axis); axiFlag_3 can be used to indicate whether it is necessary to correct the dimension value of the vertex in the z-axis (or x-axis or y-axis).

The value of axiFlag can be used to indicate whether the dimension value of the vertex in a certain axis needs to be corrected. For example: axiFlag_1=1 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected, and axiFlag_1=0 indicates that the dimension value of the vertex in the x-axis direction does not need to be corrected; axiFlag_2=1 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected, and axiFlag_2=0 indicates that the dimension value of the vertex in the y-axis direction does not need to be corrected; axiFlag_3=1 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected, and axiFlag_3=0 indicates that the dimension value of the vertex in the z-axis direction does not need to be corrected.

It should be noted that, when axiFlag indicates that the dimension value of the vertex in a certain axis does not need to be corrected, the first flag does not include the flag 3 corresponding to the axis.

(3) Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or the negative direction of the target axis.

Flag 3 can be denoted as flag01. Flag01 is used to indicate the direction in which the vertex dimension value in a certain axis needs to be corrected. For example, flag01 can include flag01_1, flag01_2, and flag01_3, where flag01_1, flag01_2, and flag01_3 correspond to the x, y, and z axes, respectively. The correspondence between the two is not limited here.

For example: flag01_1 can be used to indicate the correction direction when the dimension value of the vertex in the x-axis (or y-axis or z-axis) needs to be corrected; flag01_2 can be used to indicate the correction direction when the dimension value of the vertex in the y-axis (or z-axis or x-axis) needs to be corrected; flag01_3 can be used to indicate the correction direction when the dimension value of the vertex in the z-axis (or x-axis or y-axis) needs to be corrected.

The value of flag01 can be used to indicate the correction direction, for example: flag01_1=1 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected in the positive direction of the x-axis; flag01_1=0 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected in the negative direction of the x-axis; flag01_2=1 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected in the positive direction of the y-axis; flag01_2=0 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected in the negative direction of the y-axis; flag01_3=1 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected in the positive direction of the z-axis; flag01_3=0 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected in the negative direction of the z-axis.

In this embodiment, the decoding end decodes the first flag, which may include one or more flags for indicating point cloud distribution information. According to the one or more flags, the decoding end can determine the correction status of the vertex and thus process the vertex.

As an optional embodiment, decoding the first code stream to obtain the first flag includes:

Decoding the first code stream to obtain flag 1;

If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, decoding the flag 2 corresponding to the first axis; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, decoding the flag 3 corresponding to the first axis;

Decode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, decode the flag 3 corresponding to the second axis;

And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; decode the mark 3 corresponding to the third axis.

In this embodiment, when decoding the first bitstream, the decoding end first decodes flag 1 (nodeflag) and decodes flag 2 (axiFlag) according to the indication of flag 1. If flag 1 indicates that a vertex requires correction, flag 2 is decoded; if flag 1 indicates that no vertex requires correction, flag 2 does not need to be decoded. When decoding flag 2, two axial flags 2 can be first decoded according to the bitstream order, and the need to decode the third axial flag 2 can be determined based on the two axial flags 2. Whether to decode flag 3 (flag01) is determined based on the indication of flag 2. If flag 2 indicates that the dimension value of the vertex in a certain axis does not need to be corrected, then the flag 3 of that axis does not need to be decoded. If both axial flags 2 indicate that the dimension value of the vertex in the corresponding axis does not need to be corrected, then the third axial flag 2 does not need to be decoded. It can be directly determined that the third axial flag 2 indicates that the dimension value of the vertex in that axis requires correction (because flag 1 indicates that a vertex requires correction, if both axial flags 2 indicate that no correction is required, then the third axial flag 2 must indicate that the dimension value of the vertex in that axis requires correction).

The following example illustrates the process of decoding the first flag at the decoding end. The decoding code is as follows:

The decoding process is described as follows: the decoding end first decodes nodeflag. If nodeflag indicates that there is a vertex that needs to be corrected (such as nodeflag=1), it decodes axiFlag_1 (assuming that axiFlag_1 corresponds to the y-axis); if axiFlag_1 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected (such as axiFlag_1=1), it decodes flag01_1 corresponding to the y-axis; decodes axiFlag_2 (assuming that axiFlag_2 corresponds to the z-axis); if axiFlag_2 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected, it decodes flag01_2 corresponding to the z-axis; if axiFlag_1 indicates that the dimension value of the vertex in the y-axis direction does not need to be corrected (such as axiFlag_1=0), and axiFlag_2 both indicate that the dimension value of the vertex in the z-axis direction does not need to be corrected (such as axiFlag_2=0), it can be determined that axiFlag_3 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected (such as axiFlag_3=1); decode flag01_3.

As an optional embodiment, processing the vertices in the geometric structure according to the first flag includes:

Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag;

Determining the type of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body;

The vertex is processed according to the type of the vertex.

In this embodiment, after the decoding end decodes the first flag, it can mark whether the original point cloud exists in the eight sub-geometric bodies divided by the current node according to the decoded nodeflag and the three axial axiFlag and flag01. The vertices in this node are qualified, the type of the vertex is determined, and the vertex is processed or not processed according to the type of the vertex. Among them, the type of the vertex may include: a first type of vertex, which is an unreasonable vertex, for example, there is no original point cloud around the vertex; a second type of vertex, which is a more reasonable vertex, for example, the number of original point clouds around the vertex is small, such as the number of original point clouds is less than or equal to a threshold; a third type of vertex, which is a reasonable vertex. Reasonable vertices can be left unprocessed.

Optionally, determining the type of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body includes at least one of the following:

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs;

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located;

In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices.

In this embodiment, when the four sub-geometric bodies within the first plane to which the vertex belongs are marked as not existing in the original point cloud, the vertex is determined to be an unreasonable vertex, that is, the first type of vertex. For example, as shown in Figure 6, assuming that the edge where the vertex belongs is the edge of the bottom surface in Figure 6 (the edge where sub-geometric bodies 0 and 4 are located), then the first plane to which the edge belongs can be the surface where sub-geometric bodies 0, 1, 4, and 5 are located, or the surface where sub-geometric bodies 0, 2, 4, and 6 are located; if sub-geometric bodies 0, 1, 4, and 5 or sub-geometric bodies 0, 2, 4, and 6 do not exist in the original point cloud, then the vertex is a first type of vertex, that is, an unreasonable vertex.

When the sub-geometry within the first vertical plane of the edge where the vertex is located does not have an original point cloud, and the vertex is in the sub-geometry of the first vertical plane, the vertex is determined to be a more reasonable vertex, that is, the second type vertex. For example, as shown in Figure 6, assuming that the edge where the vertex is located is the edge of the bottom surface in Figure 6 (an edge where sub-geometry 0 and 4 are located), the first vertical plane of the edge can be the surface where sub-geometry 0, 1, 2, 3 is located or the surface where sub-geometry 4, 5, 6, 7 is located. If the sub-geometry 0, 1, 2, 3 does not have an original point cloud and the vertex is in any one of the sub-geometry 0, 1, 2, 3, then the vertex is determined to be a second type vertex, or if the sub-geometry 4, 5, 6, 7 does not have an original point cloud and the vertex is in any one of the sub-geometry 4, 5, 6, 7, then the vertex is determined to be a second type vertex, that is, a more reasonable vertex.

In this geometric structure, vertices other than the first type vertices and the second type vertices are considered to be reasonable vertices, namely the third type vertices.

Optionally, processing the vertex according to the type of the vertex includes at least one of the following:

1) Delete the first type of vertices; that is, delete unreasonable vertices;

2) Correcting the second type of vertex to the midpoint of the edge where the second type of vertex is located; that is, correcting the more reasonable vertex to the midpoint of the edge where the vertex is located.

Optionally, the third type of vertices, i.e., reasonable vertices, are not processed.

As an optional embodiment, the method further includes:

The second code stream is decoded to obtain a second flag, where the second flag is used to indicate whether the geometric reconstruction technology is enabled or not.

In an embodiment of the present application, the encoder encodes a flag indicating whether the geometric reconstruction method of the present application is enabled to obtain a second bitstream. The decoder decodes the second bitstream to determine whether the geometric reconstruction method is enabled. If the geometric reconstruction method is enabled, the implementation process of the geometric reconstruction method of the embodiment of the present application is performed. Optionally, the second bitstream and the first bitstream can be the same bitstream or different bitstreams.

Optionally, the decoding end may decode the second bitstream when Trisoup is enabled. The encoding end may encode a flag indicating whether Trisoup is enabled; and the decoding end may determine whether Trisoup is enabled by decoding the flag.

Optionally, before decoding the first code stream and obtaining the first flag, the method further includes:

Determine that the vertices in the geometric structure corresponding to the Trisoup node meet the first condition;

The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold.

In this embodiment, whether a Trisoup node enables the geometric reconstruction method of the present application is determined by the value of eligible. When the total number of vertices in the node is greater than or equal to the threshold Num and the ratio P of the number of vertices in the second region along any axis to the total number of vertices is greater than or equal to the threshold pth1, the value of eligible is set to 1, indicating that the Trisoup node executes the geometric reconstruction method of the present application. That is, if the vertices in the geometric structure corresponding to the Trisoup node meet the first condition, the decoding end needs to decode the first bitstream; otherwise, the value of eligible is set to 0, indicating that the Trisoup node does not execute the geometric reconstruction method of the present application, and the decoding end does not need to decode the first bitstream.

The second region may be a threshold range, and the second region may be a semi-axis region of a certain axis. For example, the second region may be the negative semi-axis or the positive semi-axis of a certain axis. The first condition may be, for example: the total number of vertices is greater than or equal to the second threshold, and the ratio P of the number of vertices in a semi-axis region of any axis to the total number of vertices is greater than or equal to a third threshold. The any axis may be any one or more of the x-axis, y-axis, and z-axis.

For example: if the distance between the x-axis dimension value of the vertex coordinate and the x-axis dimension value of the starting point of the edge where the vertex is located is less than the threshold value th1, the vertex is considered to be located on the negative half-axis of the x-axis. In this case, the ratio of the number of vertices in the second region along the x-axis to the total number of vertices is: the ratio of the number of vertices in the negative half-axis of the x-axis to the total number of vertices. If the distance between the x-axis dimension value of the vertex coordinate and the x-axis dimension value of the end point of the edge where the vertex is located is less than the threshold value th2, the vertex is considered to be located on the positive half-axis of the x-axis. In this case, the ratio of the number of vertices in the second region along the x-axis to the total number of vertices is: the ratio of the number of vertices in the positive half-axis of the x-axis to the total number of vertices.

As an optional embodiment, reconstructing the point cloud using the processed vertices includes:

Determine the position of the centroid vertex after the offset based on the processed vertex;

Decode the third code stream and determine the face vertices of the Trisoup node;

constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices;

Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud.

In this embodiment, the decoding end decodes the quantized offset value of the centroid vertex in the bitstream; calculates the initial position of the centroid vertex based on the vertex coordinates remaining after processing; sums the inverse quantized offset value and the initial position of the centroid vertex to obtain the position of the centroid vertex after the offset;

Optionally, the third code stream and the first code stream can be the same code stream or different code streams. Decode the information on whether face vertices exist to obtain the TriSoup face vertices corresponding to each TriSoup node; sort the vertex coordinates and face vertex coordinates in each node, and then use the edge vertices, offset centroid vertices and face vertices to construct triangular face patches. The encoding end selectively determines the face vertices for each node, and encodes and sends it to the decoding end; the decoding end decodes the information on whether vertices exist to obtain the TriSoup face vertices corresponding to each TriSoup node; the decoding end sorts the vertex coordinates and face vertex coordinates in each node, and then uses the edge vertices, offset centroid vertices and face vertices to construct triangular face patches; perform ray tracing sampling on the triangular face patches to obtain a reconstructed point cloud.

In the embodiment of the present application, the decoding process includes the following three steps:

1) Decode the Trisoup edge vertices located on the Trisoup edge to obtain the axial distribution information of the vertices and the total number of vertices;

2) Construct a Trisoup triangle on the Trisoup node;

3) Determine the decoding point by trisoup triangle voxelization.

This solution first needs to transmit the flag indicating whether the geometric reconstruction method of this application is enabled when trisoup is enabled (trisoup_enabled_flag = true), which belongs to the gbh parameter set; when the flag indicates that the geometric reconstruction method of this application is enabled, an eligible operation is performed, and the distribution information and vertex number information within the node are used to infer whether the node actually enables the geometric reconstruction method of this application.

When determining whether the node enables the geometric reconstruction method, the decoding end decodes the Trisoup edge vertices located on the Trisoup edge, and then decodes the first flag used to represent the distribution of the original point cloud in the trisoup node. The first flag includes nodeFlag, axiFlag, and flag01. Optionally, the decoding end designs a corresponding context for the flag that needs to be decoded. The decoding end determines whether the vertices in the node can directly participate in the process of constructing the Trisoup triangle of this node, and processes the vertices based on the determination result; constructs the Trisoup triangle based on the remaining nodes after processing, and then determines the decoding point by voxelizing the Trisoup triangle.

The decoding process at the decoding end is shown in Figure 7, including:

Determine the total number of vertices (vertex) of the geometric structure corresponding to the Trisoup node;

Determine whether the total number of vertices is greater than or equal to a threshold. If the total number of vertices is greater than or equal to the threshold, and the ratio P of the number of vertices in the second region along any axis to the total number of vertices is greater than or equal to the threshold th1, set eligible = 1 to instruct the Trisoup node to enable the geometric reconstruction method of the present application. Otherwise, set eligible = 0 to instruct the Trisoup node not to enable the geometric reconstruction method of the present application.

In the case of eligible=1, decode nodeflag;

Determine the value of nodeflag. If nodeflag = 1, indicating that there is a vertex that needs to be corrected, decode axiFlag_z; if axiFlag_z = 1, indicating that the dimension value of the vertex in the z-axis direction needs to be corrected, decode flag01_z corresponding to the z-axis.

Decode axiFlag_y. If axiFlag_y = 1, indicating that the dimension value of the vertex in the y-axis direction needs to be corrected, then decode flag01_y corresponding to the y-axis.

If axiFlag_z = 0 and axiFlag_y = 0, then axiFlag_x = 1, that is, the dimension value of the vertex in the x-axis direction needs to be corrected, then flag01_x is decoded and the vertex is corrected according to the value of flag01_x (modify edge vertex);

If axiFlag_z = 1 and/or axiFlag_y = 1, that is, axiFlag_z = 0 and axiFlag_y = 0 are not satisfied, then decode axiFlag_x; determine the value of axiFlag_x. If axiFlag_x = 1, it indicates to modify the dimension value of the vertex in the x-axis direction; decode flag01_x and modify the vertex (modify edge vertex) according to the value of flag01_x.

Ray tracing sampling is performed using the corrected vertices, centroid vertices, and face vertices to obtain a reconstructed point cloud.

In this embodiment, it is necessary to decode whether the geometric reconstruction technology of the present application is turned on when the trisoup technology is enabled. The distribution of vertices and the total number of vertices in the trisoup node are used to adaptively select whether to turn on the geometric reconstruction technology of the present application. For the nodes that turn on this technology, three groups of context models are constructed again using the distribution of vertices in the trisoup node, which are used to decode the nodeFlag, axiFlag, and flag01 that represent the distribution of the original point cloud in the node. In addition, the geometric structure corresponding to each Trisoup node is divided into sub-geometries, and the decoded flag is used to infer the original point cloud distribution of the sub-geometries in the node, which is then used to judge the rationality of each vertex in the node. After different processing is performed on the vertices judged to be of different rationality, the subsequent point cloud reconstruction process is carried out.

In an embodiment of the present application, a decoding end decodes and obtains a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed, and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

As shown in FIG8 , an embodiment of the present application further provides a geometric reconstruction method, which is performed by an encoding end. The method includes:

Step 801: The encoder encodes a first flag to obtain a first bitstream, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node.

Step 802: The encoding end processes the vertices in the geometric structure according to the first flag;

Step 803: The encoder reconstructs the point cloud using the processed vertices.

Optionally, for each Trisoup node, the encoding end may determine a vertex presence flag and a quantized vertex position for each edge of the geometric structure corresponding to the Trisoup node, wherein the quantized vertex position exists when the vertex presence flag indicates that a vertex exists.

The encoder may reorder the non-repeated edges in lexicographic order to determine an encoding order. The encoder may use neighbor information to determine the context of the vertex existence flag and the vertex position, and encode the vertex existence flag and the quantized vertex position into a bitstream using a dynamic and instantaneously updated optimal binarization technique (Optional Binarization with Update on the Fly, OBUF) according to the determined encoding order.

In this embodiment, the encoding end can determine a first flag based on the point cloud distribution information. The first flag is used to represent the original point cloud distribution information of the Trisoup node. The encoding end encodes the first flag to generate a first code stream and sends it to the decoding end. The encoding end determines the qualifications of the vertices in the Trisoup node based on the first flag. For example, the encoding end determines reasonable vertices, unreasonable vertices, relatively reasonable vertices, etc. based on the first flag, and deletes or corrects the vertices according to the judgment results. Optionally, when the encoding end determines that the vertex is a reasonable vertex, it does not process the reasonable vertex. After processing the vertex, the encoding end uses the processed vertex to reconstruct the point cloud.

Optionally, the first flag may include one or more flags, that is, the encoding end may determine one or more flags for indicating the distribution of the original point cloud, and encode the one or more flags so that the decoding end can obtain one or more flags through decoding.

In an embodiment of the present application, the encoding end determines and encodes a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed, and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

As an optional embodiment, the method further includes:

Marking original point cloud distribution information of sub-geometric bodies corresponding to child nodes of the Trisoup node according to original point cloud distribution information within the geometric structure corresponding to the Trisoup node, where the sub-geometric bodies are obtained by dividing the geometric structure;

The first flag is determined according to the original point cloud distribution information of the sub-geometric body and the vertex existence flag of the edge of the geometric structure.

In this embodiment, the decoding end can divide the Trisoup node into multiple sub-geometric bodies, as shown in Figure 6, and give the sub-geometric body a flag indicating whether the original point cloud exists based on the original point cloud distribution information in the node; the decoding end determines the first flag based on the point cloud occupancy information and vertex existence flag information of the multiple sub-geometric bodies divided by the Trisoup node.

Among them, the first mark may include one or more flags, which may be flags corresponding to different axes. For example, the first mark includes mark 1, mark 2 and mark 3, among which mark 2 may include mark 2 corresponding to the three axes of x, y, and z respectively, and mark 3 may include mark 3 corresponding to the three axes of x, y, and z respectively.

As an optional embodiment, the first flag includes at least one of the following:

(1) Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected; Flag 1 can be denoted as nodeflag, which is used to indicate whether there are vertices in the geometric structure corresponding to the Trisoup node that need to be processed. For example, nodeflag = 1 indicates that there are vertices in the geometric structure that need to be processed, and nodeflag = 0 indicates that there are no vertices in the geometric structure that need to be processed. It should be noted that when nodeflag indicates that there are no vertices in the geometric structure that need to be processed, the first flag does not include flags 2 and 3.

(2) Flag 2: used to indicate whether it is necessary to correct the dimension value of the vertex in the target axis, and the target axis is any of the three axes; the flag 2 can be recorded as axiFlag, and axiFlag is used to indicate based on which circumferential axis the dimension value of the vertex needs to be corrected, for example: axiFlag can include axiFlag_1, axiFlag_2, axiFlag_3, axiFlag_1, axiFlag-_2, axiFlag_3 correspond to the x-axis, y-axis, and z-axis respectively, and the correspondence between the two is not limited here. For example: axiFlag_1 can be used to indicate whether it is necessary to correct the dimension value of the vertex in the x-axis (or y-axis or z-axis); axiFlag_2 can be used to indicate whether it is necessary to correct the dimension value of the vertex in the y-axis (or z-axis or x-axis); axiFlag_3 can be used to indicate whether it is necessary to correct the dimension value of the vertex in the z-axis (or x-axis or y-axis).

The value of axiFlag can be used to indicate whether the dimension value of the vertex in a certain axis needs to be corrected. For example: axiFlag_1=1 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected, and axiFlag_1=0 indicates that the dimension value of the vertex in the x-axis direction does not need to be corrected; axiFlag_2=1 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected, and axiFlag_2=0 indicates that the dimension value of the vertex in the y-axis direction does not need to be corrected; axiFlag_3=1 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected, and axiFlag_3=0 indicates that the dimension value of the vertex in the z-axis direction does not need to be corrected.

It should be noted that, when axiFlag indicates that the dimension value of the vertex in a certain axis does not need to be corrected, the first flag does not include the flag 3 corresponding to the axis.

(3) Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or the negative direction of the target axis.

Flag 3 can be denoted as flag01. Flag01 is used to indicate the direction in which the vertex dimension value in a certain axis needs to be corrected. For example, flag01 can include flag01_1, flag01_2, and flag01_3, where flag01_1, flag01_2, and flag01_3 correspond to the x, y, and z axes, respectively. The correspondence between the two is not limited here.

For example: flag01_1 can be used to indicate the correction direction when the dimension value of the vertex in the x-axis (or y-axis or z-axis) needs to be corrected; flag01_2 can be used to indicate the correction direction when the dimension value of the vertex in the y-axis (or z-axis or x-axis) needs to be corrected; flag01_3 can be used to indicate the correction direction when the dimension value of the vertex in the z-axis (or x-axis or y-axis) needs to be corrected.

The value of flag01 can be used to indicate the correction direction, for example: flag01_1=1 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected in the positive direction of the x-axis; flag01_1=0 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected in the negative direction of the x-axis; flag01_2=1 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected in the positive direction of the y-axis; flag01_2=0 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected in the negative direction of the y-axis; flag01_3=1 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected in the positive direction of the z-axis; flag01_3=0 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected in the negative direction of the z-axis.

In this embodiment, the encoding end further processes according to the three dimensions of x, y, and z to obtain nodeFlag, axiFlag, and flag01. The encoding end can determine the values of the three flags based on the point cloud distribution information of the multiple sub-geometric bodies divided by a node and the vertex existence flag information. For example, taking the x dimension as an example, as shown in Figure 6, when the four sub-geometric bodies on the left are all marked as not having the original point cloud and there are vertices on the four left edges of the Tirsoup node, flag01_x = 0, axiFlag_x = 1; or when the four sub-geometric bodies on the right are all marked as not having the original point cloud and there are vertices on the four right edges of the Tirsoup node, flag01_x = 1, axiFlag_x = 1; otherwise, axiFlag_x = 0, and flag01_x does not exist. Similarly, axiFlag_y, flag01_y and axiFlag_z, flag01_z of each node can be obtained in the y and z dimensions. When any one of the values of axiFlag_x, axiFlag_y, and axiFlag_z is 1, nodeflag=1 (indicating that there is a vertex that needs to be corrected), otherwise nodeflag=0 (indicating that there is no vertex that needs to be corrected).

As an optional embodiment, the method further includes:

determining a context of the first marker;

The encoding of the first flag to obtain the first code stream includes: encoding the first flag according to the context to obtain the first code stream.

Optionally, determining the context of the first flag includes:

Determining the context of the first marker based on vertex distribution information within the geometric structure corresponding to the Trisoup node;

The context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes.

In this embodiment, the encoding end may determine a context based on vertex distribution information within a node, and use the context to encode the first flag.

The target axis can be any of the three axes: x, y, and z. If the first flag includes multiple flags, the context can include contexts corresponding to the multiple flags. For example, if the first flag includes flag 1, flag 2, and flag 3, the context can include the context of flag 2 and the context of flag 3.

When encoding the first flag at the encoding end, the context corresponding to the axis to be encoded is used. For example, when encoding the flag corresponding to the x-axis 2, the context corresponding to the x-axis is used, that is, whether the ratio of the number of vertices in the first area along the x-axis to the total number of vertices is greater than or equal to the first threshold; when encoding the flag corresponding to the y-axis 2, the context corresponding to the y-axis is used, that is, whether the ratio of the number of vertices in the first area along the y-axis to the total number of vertices is greater than or equal to the first threshold; when encoding the flag corresponding to the z-axis 3, the context corresponding to the z-axis is used, that is, whether the ratio of the number of vertices in the first area along the z-axis to the total number of vertices is greater than or equal to the first threshold. The encoding end can use the context to encode nodeFlag, axiFlag, and flag01 to obtain the first code stream.

Optionally, the first area may be a preset range of the target area, and the first area may be recorded as the negative semi-axis or the positive semi-axis. For example, if the distance between the target axial dimension value of the vertex coordinate and the target axial dimension value of the starting point of the edge where the vertex is located is less than a first predetermined threshold, the vertex is considered to be located on the negative semi-axis of the target axial direction. In this case, the ratio of the number of vertices in the first area of the target axial direction to the total number of vertices is: the ratio of the number of vertices in the negative semi-axis of the target axial direction to the total number of vertices. If the distance between the target axial dimension value of the vertex coordinate and the target axial dimension value of the end point of the edge where the vertex is located is less than a second predetermined threshold, the vertex is considered to be located on the positive semi-axis of the target axial direction. In this case, the ratio of the number of vertices in the first area of the target axial direction to the total number of vertices is: the ratio of the number of vertices in the positive semi-axis of the target axial direction to the total number of vertices.

When the first area is the negative semi-axis or the positive semi-axis of the target axis, the first threshold indicated in the context may be different, for example: the context indicates whether the ratio of the number of vertices in the negative semi-axis of the target axis to the total number of vertices is greater than th1, or the context indicates whether the ratio of the number of vertices in the positive semi-axis of the target axis to the total number of vertices is greater than th2, and th1 and th2 may be different.

As an optional embodiment, encoding the first flag includes:

Coding mark 1;

If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, the flag 2 corresponding to the first axis is encoded; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, the flag 3 corresponding to the first axis is encoded;

Encode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, then encode the flag 3 corresponding to the second axis;

And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; encode the mark 3 corresponding to the third axis.

In this embodiment, when encoding the first code stream, the encoding end first encodes flag 1 (nodeflag), and encodes flag 2 (axiFlag) according to the indication of flag 1; wherein, if flag 1 indicates that there is a vertex that needs to be corrected, flag 2 is encoded, and if flag 1 indicates that there is no vertex that needs to be corrected, flag 2 does not need to be encoded. When encoding flag 2, two axial flags 2 can be encoded first in order, and it is determined whether the third axial flag 2 needs to be encoded based on the two axial flags 2; it is determined whether flag 3 (flag01) is encoded based on the indication of flag 2, and when flag 2 indicates that the dimensional value of the vertex in a certain axis does not need to be corrected, the flag 3 of the axis does not need to be encoded. When both axial flags 2 indicate that the dimensional value of the vertex in the corresponding axis does not need to be corrected, it is determined that the third axial flag 2 indicates that the dimensional value of the vertex in the axis needs to be corrected (because flag 1 indicates that there is a vertex that needs to be corrected, if both axial flags 2 indicate that no correction is required, then the third axial flag 2 must indicate that the dimensional value of the vertex in the axis needs to be corrected).

The following example illustrates the process of encoding the first flag at the encoding end. The encoding code is as follows:

The encoding process is described as follows: the encoding end first encodes nodeflag. If nodeflag indicates that there is a vertex that needs to be corrected (such as nodeflag=1), axiFlag_1 is encoded (assuming axiFlag_1 corresponds to the y-axis); if axiFlag_1 indicates that the dimension value of the vertex in the y-axis direction needs to be corrected (such as axiFlag_1=1), flag01_1 corresponding to the y-axis is encoded; axiFlag_2 is encoded (assuming axiFlag_2 corresponds to the z-axis); if axiFlag_2 indicates that the dimension value of the vertex in the z-axis direction needs to be corrected, flag01_2 corresponding to the z-axis is encoded; if axiFlag_1 indicates that the dimension value of the vertex in the y-axis direction does not need to be corrected (such as axiFlag_1=0), and axiFlag_2 both indicate that the dimension value of the vertex in the z-axis direction does not need to be corrected (such as axiFlag_2=0), it can be determined that axiFlag_3 indicates that the dimension value of the vertex in the x-axis direction needs to be corrected (such as axiFlag_3=1); flag01_3 is encoded.

As an optional embodiment, processing the vertices in the geometric structure according to the first flag includes:

Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag;

Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body;

The vertex is processed according to the type of the vertex.

In this embodiment, the encoding end can mark whether the eight sub-geometric bodies divided by the current node have the original point cloud based on nodeflag and the three axial directions axiFlag and flag01. The vertices in this node are qualified to determine the type of the vertex, and the vertex is processed or not processed according to the type of the vertex. The vertex type may include: a first type vertex, which is an unreasonable vertex; a second type vertex, which is a relatively reasonable vertex; and a third type vertex, which is a reasonable vertex. Reasonable vertices may not be processed.

Optionally, determining the type of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body includes at least one of the following:

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs;

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located;

In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices.

In this embodiment, when the four sub-geometric bodies within the first plane to which the vertex belongs are marked as not existing in the original point cloud, the vertex is determined to be an unreasonable vertex, that is, the first type of vertex. For example, as shown in Figure 6, assuming that the edge where the vertex belongs is the edge of the bottom surface in Figure 6 (the edge where sub-geometric bodies 0 and 4 are located), then the first plane to which the edge belongs can be the surface where sub-geometric bodies 0, 1, 4, and 5 are located, or the surface where sub-geometric bodies 0, 2, 4, and 6 are located; if sub-geometric bodies 0, 1, 4, and 5 or sub-geometric bodies 0, 2, 4, and 6 do not exist in the original point cloud, then the vertex is a first type of vertex, that is, an unreasonable vertex.

When the sub-geometry within the first vertical plane of the edge where the vertex is located does not have an original point cloud, and the vertex is in the sub-geometry of the first vertical plane, the vertex is determined to be a more reasonable vertex, that is, the second type vertex. For example, as shown in Figure 6, assuming that the edge where the vertex is located is the edge of the bottom surface in Figure 6 (an edge where sub-geometry 0 and 4 are located), the first vertical plane of the edge can be the surface where sub-geometry 0, 1, 2, 3 is located or the surface where sub-geometry 4, 5, 6, 7 is located. If the sub-geometry 0, 1, 2, 3 does not have an original point cloud and the vertex is in any one of the sub-geometry 0, 1, 2, 3, then the vertex is determined to be a second type vertex, or if the sub-geometry 4, 5, 6, 7 does not have an original point cloud and the vertex is in any one of the sub-geometry 4, 5, 6, 7, then the vertex is determined to be a second type vertex, that is, a more reasonable vertex.

In this geometric structure, vertices other than the first type vertices and the second type vertices are considered to be reasonable vertices, namely the third type vertices.

Optionally, processing the vertex according to the type of the vertex includes at least one of the following:

Delete the first type of vertices; that is, delete unreasonable vertices;

Correct the second type vertex to the midpoint of the edge where the second type vertex is located; that is, correct the more reasonable vertex to the midpoint of the edge where the vertex is located.

Optionally, the third type of vertices, i.e., reasonable vertices, are not processed.

As an optional embodiment, the method further includes:

The second flag is encoded into a second code stream, where the second flag is used to indicate whether to enable or not enable the geometric reconstruction technology.

In an embodiment of the present application, the encoder encodes a flag indicating whether the geometric reconstruction method of the present application is enabled to obtain a second bitstream; when the geometric reconstruction method is enabled, the implementation process of the geometric reconstruction method of the embodiment of the present application is performed. Optionally, the second bitstream and the first bitstream can be the same bitstream or different bitstreams.

Optionally, the encoding end may encode the second flag into a second code stream when Trisoup is enabled.

Optionally, the encoding end may encode a flag indicating whether Trisoup is enabled; and the decoding end may determine whether Trisoup is enabled by decoding the flag.

Optionally, before determining the first marker, the method further includes:

Determine that the vertices in the geometric structure corresponding to the Trisoup node meet the first condition;

The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold.

In this embodiment, whether the Trisoup node enables the geometric reconstruction method of the present application is determined by the value of eligible. When the total number of vertices in the node is greater than or equal to the threshold value Num and the ratio P of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to the threshold value pth1, the value of eligible is set to 1, indicating that the Trisoup node executes the geometric reconstruction method of the present application, that is, when the vertices in the geometric structure corresponding to the Trisoup node meet the first condition, the encoder needs to encode the first bitstream; otherwise, the value of eligible is set to 0, indicating that the Trisoup node does not execute the geometric reconstruction method of the present application, and the encoder does not need to encode the first bitstream.

The second region may be a threshold range, and the second region may be a semi-axis region of a certain axis. For example, the second region may be the negative semi-axis or the positive semi-axis of a certain axis. The first condition may be, for example: the total number of vertices is greater than or equal to the second threshold, and the ratio P of the number of vertices in a semi-axis region of any axis to the total number of vertices is greater than or equal to a third threshold. The any axis may be any one or more of the x-axis, y-axis, and z-axis.

For example: if the distance between the x-axis dimension value of the vertex coordinate and the x-axis dimension value of the starting point of the edge where the vertex is located is less than the threshold value th1, the vertex is considered to be located on the negative half-axis of the x-axis. In this case, the ratio of the number of vertices in the second region along the x-axis to the total number of vertices is: the ratio of the number of vertices in the negative half-axis of the x-axis to the total number of vertices. If the distance between the x-axis dimension value of the vertex coordinate and the x-axis dimension value of the end point of the edge where the vertex is located is less than the threshold value th2, the vertex is considered to be located on the positive half-axis of the x-axis. In this case, the ratio of the number of vertices in the second region along the x-axis to the total number of vertices is: the ratio of the number of vertices in the positive half-axis of the x-axis to the total number of vertices.

As an optional embodiment, reconstructing the point cloud using the processed vertices includes:

Determine the position of the centroid vertex after the offset based on the processed vertex;

Determining face vertices for the Trisoup node, and encoding existence information of the face vertices to obtain a third code stream;

constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices;

Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud.

In this embodiment, after deleting or modifying the vertices, the encoder calculates the initial position of the centroid vertex based on the processed vertices. It then calculates an offset value for the centroid vertex based on the original point cloud surrounding the initial position. This offset value is then quantized and encoded into the bitstream. The inverse quantized drift value is summed with the initial position of the centroid vertex to obtain the offset position of the centroid vertex.

The encoder selectively determines face vertices for each node. The face vertices are encoded and sent to the decoder. The encoder sorts the vertex coordinates and face vertex coordinates within each node, constructs triangular facets using edge vertices, offset centroid vertices, and face vertices, and performs ray tracing sampling on the triangular facets to obtain a reconstructed point cloud.

The encoding process at the encoding end is shown in Figure 9, including:

Determine the total number of vertices (vertex) of the geometric structure corresponding to the Trisoup node according to the distribution of the point cloud;

Determine whether the total number of vertices is greater than or equal to a threshold. If the total number of vertices is greater than or equal to the threshold, and the ratio P of the number of vertices in the second region along any axis to the total number of vertices is greater than or equal to the threshold th1, set eligible = 1 to instruct the Trisoup node to enable the geometric reconstruction method of the present application. Otherwise, set eligible = 0 to instruct the Trisoup node not to enable the geometric reconstruction method of the present application.

In the case of eligible=1, the geometric structure corresponding to the Trisoup node is divided into eight sub-geometric bodies, as shown in Figure 6. The flag (8) indicating whether the original point cloud exists is given to the eight sub-geometric bodies according to the original point cloud information in the node.

Determine nodeflag, axiFlag corresponding to each axis, and flag01;

Encode nodeflag; determine the value of nodeflag. If nodeflag = 1, it indicates that there is a vertex that needs to be corrected, and encode axiFlag_z. If axiFlag_z = 1, it indicates that the dimension value of the vertex in the z-axis direction needs to be corrected, and encode flag01_z corresponding to the z-axis direction.

Encode axiFlag_y. If axiFlag_y = 1, indicating that the dimension value of the vertex in the y-axis direction needs to be corrected, then decode and encode flag01_y corresponding to the y-axis.

If axiFlag_z = 0 and axiFlag_y = 0, then axiFlag_x = 1, that is, the dimension value of the vertex in the x-axis direction needs to be corrected, then flag01_x is encoded, and the vertex is corrected according to the value of flag01_x (modify edge vertex);

If axiFlag_z = 1 and/or axiFlag_y = 1, that is, axiFlag_z = 0 and axiFlag_y = 0 are not satisfied, then encode axiFlag_x; determine the value of axiFlag_x, if axiFlag_x = 1, it indicates to modify the dimension value of the vertex in the x-axis direction; encode flag01_x, and modify the vertex (modify edge vertex) according to the value of flag01_x;

Ray tracing sampling is performed using the corrected vertices, centroid vertices, and face vertices to obtain a reconstructed point cloud.

In this embodiment, it is necessary to decode whether the geometric reconstruction technology of the present application is turned on when the trisoup technology is enabled. The distribution of vertices and the total number of vertices in the trisoup node are used to adaptively select whether to turn on the geometric reconstruction technology of the present application. For the nodes that turn on this technology, three groups of context models are constructed again using the distribution of vertices in the trisoup node, which are used to encode the nodeFlag, axiFlag, and flag01 that represent the distribution of the original point cloud in the node. In addition, the geometric structure corresponding to each Trisoup node is divided into sub-geometries, and each flag is used to indicate the original point cloud distribution of the sub-geometries in the node, which is then used to judge the rationality of each vertex in the node. After different processing is performed on the vertices judged to be of different rationality, the subsequent point cloud reconstruction process is carried out.

In an embodiment of the present application, the encoding end determines and encodes a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed, and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

The geometric reconstruction method provided in the embodiment of the present application can be executed by a geometric reconstruction device. In the embodiment of the present application, the geometric reconstruction device provided in the embodiment of the present application is described by taking the geometric reconstruction method performed by the geometric reconstruction device as an example.

As shown in FIG10 , an embodiment of the present application provides a geometric reconstruction device 1000 , which is applied to a decoding end. The device includes:

A first decoding module 1010 is configured to decode the first code stream to obtain a first flag, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node;

A first processing module 1020, configured to process vertices in the geometric structure according to the first flag;

The second processing module 1030 is configured to reconstruct a point cloud using the processed vertices.

Optionally, the device further includes:

A first determination module is used to determine the context according to vertex distribution information in the geometric structure corresponding to the Trisoup node;

The first decoding module is specifically configured to decode the first code stream according to the context to obtain a first flag.

Optionally, the context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes.

Optionally, the first flag includes at least one of the following:

Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected;

Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes;

Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis.

Optionally, the first decoding module is specifically configured to:

Decoding the first code stream to obtain flag 1;

If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, decoding the flag 2 corresponding to the first axis; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, decoding the flag 3 corresponding to the first axis;

Decode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, decode the flag 3 corresponding to the second axis;

And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; decode the mark 3 corresponding to the third axis.

Optionally, the first processing module is specifically configured to:

Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag;

Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body;

The vertex is processed according to the type of the vertex.

Optionally, the first processing module is specifically configured to perform at least one of the following:

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs;

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located;

In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices.

Optionally, the first processing module is specifically configured to perform at least one of the following:

Delete the first type of vertex;

The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located.

Optionally, the device further includes:

The second decoding module is used to decode the second code stream to obtain a second flag, where the second flag is used to indicate whether to enable or disable the geometric reconstruction technology.

Optionally, the device further includes:

A second determination module is used to determine whether a vertex in the geometric structure corresponding to the Trisoup node satisfies a first condition;

The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold.

Optionally, the second processing module is specifically configured to

Determine the position of the centroid vertex after the offset based on the processed vertex;

Decode the third code stream and determine the face vertices of the Trisoup node;

constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices;

Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud.

In an embodiment of the present application, a decoding end decodes and obtains a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed, and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

The geometric reconstruction device provided in the embodiment of the present application can implement the various processes implemented in the method embodiments of Figures 4 to 7 and achieve the same technical effects. To avoid repetition, they will not be described here.

As shown in FIG11 , an embodiment of the present application further provides a geometric reconstruction device 1100 , which is applied to an encoding end and includes:

A first encoding module 1110 is configured to encode a first flag to obtain a first code stream, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node;

A third processing module 1120, configured to process vertices in the geometric structure according to the first flag;

The fourth processing module 1130 is configured to reconstruct a point cloud using the processed vertices.

Optionally, the device further includes: a third determining module, specifically configured to:

Marking original point cloud distribution information of sub-geometric bodies corresponding to child nodes of the Trisoup node according to original point cloud distribution information within the geometric structure corresponding to the Trisoup node, where the sub-geometric bodies are obtained by dividing the geometric structure;

The first flag is determined according to the original point cloud distribution information of the sub-geometric body and the vertex existence flag of the edge of the geometric structure.

Optionally, the first flag includes at least one of the following:

Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected;

Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes;

Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis.

Optionally, the first encoding module is specifically configured to:

Coding mark 1;

If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, the flag 2 corresponding to the first axis is encoded; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, the flag 3 corresponding to the first axis is encoded;

Encode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, then encode the flag 3 corresponding to the second axis;

And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; encode the mark 3 corresponding to the third axis.

Optionally, the device further includes:

a fourth determining module, configured to determine a context of the first sign;

The first encoding module is specifically configured to encode the first flag according to the context to obtain a first code stream.

Optionally, the fourth determining module is specifically configured to:

Determining the context of the first marker based on vertex distribution information within the geometric structure corresponding to the Trisoup node;

The context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes.

Optionally, the third processing module is specifically configured to:

Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag;

Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body;

The vertex is processed according to the type of the vertex.

Optionally, the third processing module is specifically configured to perform at least one of the following:

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs;

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located;

In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices.

Optionally, the third processing module is specifically configured to perform at least one of the following:

Delete the first type of vertex;

The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located.

Optionally, the device further includes:

The second encoding module is used to encode a second flag into a second code stream, where the second flag is used to indicate whether to enable or disable the geometric reconstruction technology.

Optionally, the device further includes:

A fifth determining module, configured to determine whether a vertex in the geometric structure corresponding to the Trisoup node satisfies a first condition;

The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold.

Optionally, the fourth processing module is specifically configured to:

Determine the position of the centroid vertex after the offset based on the processed vertex;

Determining face vertices for the Trisoup node, and encoding existence information of the face vertices to obtain a third code stream;

constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices;

Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud.

In an embodiment of the present application, the encoding end determines and encodes a first flag. Based on the first flag, the distribution of the original point cloud in the geometric structure can be determined. The vertices in the geometric structure are then processed, and the processed vertices are used to reconstruct the point cloud. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

The geometric reconstruction device provided in the embodiment of the present application can implement the various processes implemented in the method embodiments of Figures 8 to 9 and achieve the same technical effects. To avoid repetition, they will not be described here.

As shown in Figure 12, an embodiment of the present application further provides an electronic device 1200, including a processor 1201 and a memory 1202, wherein the memory 1202 stores programs or instructions that can be run on the processor 1201. For example, when the electronic device 1200 is an encoding end device, the program or instruction is executed by the processor 1201 to implement the various steps of the above-mentioned geometric reconstruction method embodiment, and can achieve the same technical effect. When the electronic device 1200 is a decoding end device, the program or instruction is executed by the processor 1201 to implement the various steps of the above-mentioned geometric reconstruction method embodiment, and can achieve the same technical effect. To avoid repetition, it is not repeated here. Optionally, the memory 1202 can be the memory 102 or the memory 113 in the embodiment shown in Figure 1, and the processor 1201 can implement the functions of the encoder 200 or the decoder 300 in the embodiment shown in Figures 1-3.

The present application also provides an electronic device including: a memory configured to store video data; and a processing circuit configured to implement the steps of the geometric reconstruction method described above. Optionally, the memory may be memory 102 or memory 113 in the embodiment shown in FIG. 1 , and the processing circuit may implement the functions of encoder 200 or decoder 300 in the embodiments shown in FIG. 1-3 .

The present application also provides an electronic device including a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is configured to execute a program or instruction to implement the steps in the method embodiment shown in FIG4 or FIG8. This device embodiment corresponds to the aforementioned method embodiment, and each implementation process and implementation method of the aforementioned method embodiment can be applied to this terminal embodiment and can achieve the same technical effects.

The above-mentioned electronic device can be a terminal or other devices other than a terminal, such as a server, a network attached storage (NAS), etc.

Among them, the terminal can be a mobile phone, tablet computer (Tablet Personal Computer), laptop computer, notebook computer, personal digital assistant (PDA), handheld computer, netbook, ultra-mobile personal computer (UMPC), mobile Internet device (MID), augmented reality (AR), virtual reality (VR) equipment, mixed reality (MR) equipment, robot, wearable device (Wearable Device), flight vehicle, vehicle user equipment (VUE), shipborne equipment, pedestrian user equipment (PUE), smart home (home appliances with wireless communication function, such as refrigerator, TV, washing machine or furniture, etc.), game console, personal computer (PC), ATM or self-service machine and other terminal side devices. Wearable devices include: smart watches, smart bracelets, smart headphones, smart glasses, smart jewelry (smart bracelets, smart bracelets, smart rings, smart necklaces, smart anklets, smart anklets, etc.), smart wristbands, smart clothing, etc. Among them, vehicle-mounted devices can also be called vehicle-mounted terminals, vehicle-mounted controllers, vehicle-mounted modules, vehicle-mounted components, vehicle-mounted chips, or vehicle-mounted units, etc. It should be noted that the specific type of terminal is not limited in the embodiments of this application.

The server can be an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server that can provide cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, content delivery networks (CDN), or cloud computing services based on big data and artificial intelligence platforms.

For example, the electronic device may include but is not limited to the source device 100 or the destination device 110 shown in FIG. 1 .

Taking an electronic device as a terminal as an example, FIG13 is a schematic diagram of the hardware structure of a terminal implementing an embodiment of the present application.

The terminal 1300 includes but is not limited to: a radio frequency unit 1301, a network module 1302, an audio output unit 1303, an input unit 1304, a sensor 1305, a display unit 1306, a user input unit 1307, an interface unit 1308, a memory 1309 and at least some of the components of the processor 1310.

Those skilled in the art will appreciate that the terminal 1300 may also include a power supply (such as a battery) to power various components. The power supply may be logically connected to the processor 1310 via a power management system, thereby enabling the power management system to manage charging, discharging, and power consumption. The terminal structure shown in FIG13 does not limit the terminal. The terminal may include more or fewer components than shown, or may combine certain components, or have different component arrangements, which will not be described in detail here.

It should be understood that in the embodiment of the present application, the input unit 1304 may include a graphics processing unit (GPU) 13041 and a microphone 13042. The graphics processor 13041 processes image data of static images or videos obtained by an image acquisition device (such as a camera) in video acquisition mode or image acquisition mode, or may process the obtained point cloud data. The display unit 1306 may include a display panel 13061, which may be configured in the form of a liquid crystal display, an organic light emitting diode, etc. The user input unit 1307 includes a touch panel 13071 and at least one of other input devices 13072. The touch panel 13071 is also called a touch screen. The touch panel 13071 may include two parts: a touch detection device and a touch controller. Other input devices 13072 may include, but are not limited to, a physical keyboard, function keys (such as volume control keys, power keys, etc.), a trackball, a mouse, and a joystick, which will not be described in detail here.

In the embodiment of the present application, after receiving downlink data from a network-side device, the RF unit 1301 may transmit the data to the processor 1310 for processing. Furthermore, the RF unit 1301 may send uplink data to the network-side device. Typically, the RF unit 1301 includes, but is not limited to, an antenna, an amplifier, a transceiver, a coupler, a low-noise amplifier, a duplexer, and the like.

Memory 1309 can be used to store software programs or instructions and various data. Memory 1309 may primarily include a first storage area for storing programs or instructions and a second storage area for storing data. The first storage area may store an operating system, applications or instructions required for at least one function (such as a sound playback function, an image playback function, etc.). Furthermore, memory 1309 may include volatile memory or non-volatile memory. The non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be random access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM (DRRAM). The memory 1309 in the embodiments of the present application includes, but is not limited to, these and any other suitable types of memory.

Processor 1310 may include one or more processing units. Optionally, processor 1310 integrates an application processor and a modem processor. The application processor primarily handles operations related to the operating system, user interface, and application programs, while the modem processor primarily processes wireless communication signals, such as a baseband processor. It is understood that the modem processor may not be integrated into processor 1310.

Wherein, when the terminal is a decoding end device:

The processor 1310 is used to: decode the first code stream to obtain a first flag, where the first flag is used to indicate the original point cloud distribution information in the geometric structure corresponding to the Trisoup node; process the vertices in the geometric structure according to the first flag; and reconstruct the point cloud using the processed vertices.

Optionally, the processor 1310 is further configured to:

Determine the context based on the vertex distribution information in the geometric structure corresponding to the Trisoup node;

The decoding of the first code stream to obtain the first flag includes:

The first code stream is decoded according to the context to obtain a first flag.

Optionally, the context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes.

Optionally, the first flag includes at least one of the following:

Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected;

Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes;

Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis.

Optionally, the processor 1310 is specifically configured to:

Decoding the first code stream to obtain flag 1;

If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, decoding the flag 2 corresponding to the first axis; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, decoding the flag 3 corresponding to the first axis;

Decode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, decode the flag 3 corresponding to the second axis;

And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; decode the mark 3 corresponding to the third axis.

Optionally, the processor 1310 is specifically configured to:

Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag;

Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body;

The vertex is processed according to the type of the vertex.

Optionally, the processor 1310 is specifically configured to perform at least one of the following:

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs;

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located;

In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices.

Optionally, the processor 1310 is specifically configured to perform at least one of the following:

Delete the first type of vertex;

The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located.

Optionally, the processor 1310 is further configured to:

The second code stream is decoded to obtain a second flag, where the second flag is used to indicate whether the geometric reconstruction technology is enabled or not.

Optionally, the processor 1310 is further configured to:

Determine that the vertices in the geometric structure corresponding to the Trisoup node meet the first condition;

The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold.

Optionally, the processor 1310 is specifically configured to:

Determine the position of the centroid vertex after the offset based on the processed vertex;

Decode the third code stream and determine the face vertices of the Trisoup node;

constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices;

Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud.

Wherein, when the terminal is an encoding terminal device:

The processor 1310 is used to: encode a first flag to obtain a first code stream, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node; process vertices in the geometric structure according to the first flag; and reconstruct a point cloud using the processed vertices.

Optionally, the processor 1310 is specifically configured to:

Marking original point cloud distribution information of sub-geometric bodies corresponding to child nodes of the Trisoup node according to original point cloud distribution information within the geometric structure corresponding to the Trisoup node, where the sub-geometric bodies are obtained by dividing the geometric structure;

The first flag is determined according to the original point cloud distribution information of the sub-geometric body and the vertex existence flag of the edge of the geometric structure.

Optionally, the first flag includes at least one of the following:

Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected;

Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes;

Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis.

Optionally, the processor 1310 is specifically configured to:

Coding mark 1;

If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, the flag 2 corresponding to the first axis is encoded; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, the flag 3 corresponding to the first axis is encoded;

Encode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, then encode the flag 3 corresponding to the second axis;

And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; encode the mark 3 corresponding to the third axis.

Optionally, the processor 1310 is further configured to:

determining a context of the first marker;

The encoding of the first flag to obtain a first code stream includes:

The first flag is encoded according to the context to obtain a first code stream.

Optionally, the processor 1310 is specifically configured to:

Determining the context of the first marker based on vertex distribution information within the geometric structure corresponding to the Trisoup node;

The context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes.

Optionally, the processor 1310 is specifically configured to:

Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag;

Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body;

The vertex is processed according to the type of the vertex.

Optionally, the processor 1310 is specifically configured to perform at least one of the following:

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs;

In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located;

In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices.

Optionally, the processor 1310 is specifically configured to perform at least one of the following:

Delete the first type of vertex;

The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located.

Optionally, the processor 1310 is further configured to:

The second flag is encoded into a second code stream, where the second flag is used to indicate whether to enable or not enable the geometric reconstruction technology.

Optionally, the processor 1310 is further configured to:

Determine that the vertices in the geometric structure corresponding to the Trisoup node meet the first condition;

The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold.

Optionally, the processor 1310 is specifically configured to:

Determine the position of the centroid vertex after the offset based on the processed vertex;

Determining face vertices for the Trisoup node, and encoding existence information of the face vertices to obtain a third code stream;

constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices;

Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud.

In an embodiment of the present application, the terminal can determine the distribution of the original point cloud in the geometric structure based on the first flag, then process the vertices in the geometric structure and reconstruct the point cloud using the processed vertices. By processing the vertices, erroneous point clouds can be removed, distortion of the reconstructed point cloud can be reduced, and the performance gain of the reconstructed point cloud can be improved.

It can be understood that the implementation process of each implementation method mentioned in this embodiment can refer to the relevant description of the geometric reconstruction method of the method embodiment, and achieve the same or corresponding technical effects. To avoid repetition, it will not be repeated here.

An embodiment of the present application also provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the various processes of the above-mentioned geometric reconstruction method embodiment are implemented and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

The processor is the processor in the terminal described in the above embodiment. The readable storage medium includes a computer-readable storage medium, such as ROM, RAM, a magnetic disk, or an optical disk. In some examples, the readable storage medium may be a non-transitory readable storage medium.

An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned geometric reconstruction method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

It should be understood that the chip mentioned in the embodiments of the present application may include a system-level chip (also referred to as a system chip, a chip system or a system-on-chip chip), and may also include an independent display chip, etc.

An embodiment of the present application further provides a computer program/program product, which is stored in a storage medium. The computer program/program product is executed by at least one processor to implement the various processes of the above-mentioned geometric reconstruction method embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

An embodiment of the present application also provides a coding and decoding system, including: an encoding end device and a decoding end device, wherein the encoding end device can be used to execute the steps of the geometric reconstruction method of the encoding end as described above, and the decoding end device can be used to execute the steps of the geometric reconstruction method of the decoding end as described above.

An embodiment of the present application also provides a computer program product, including computer instructions. When the computer instructions are executed by a processor, the steps of the above-mentioned geometric reconstruction method are implemented and the same technical effect can be achieved. To avoid repetition, they will not be repeated here.

It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted or combined. In addition, the features described with reference to certain examples may be combined in other examples.

Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of a computer software product plus a necessary general-purpose hardware platform, or of course, by hardware. The computer software product is stored in a storage medium (such as ROM, RAM, magnetic disk, optical disk, etc.) and includes a number of instructions for enabling a terminal or network-side device to execute the methods described in each embodiment of the present application.

The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms of implementation methods without departing from the purpose of this application and the scope of protection of the claims. These implementation methods are all within the protection of this application.

Claims (50)

A geometric reconstruction method, comprising: The decoding end decodes the first code stream to obtain a first flag, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a node of the triangle set Trisoup; The decoding end processes the vertices in the geometric structure according to the first flag; The decoding end reconstructs the point cloud using the processed vertices. The method according to claim 1, further comprising: Determine the context based on the vertex distribution information in the geometric structure corresponding to the Trisoup node; The decoding of the first code stream to obtain the first flag includes: The first code stream is decoded according to the context to obtain a first flag. The method according to claim 2, wherein the context is used to indicate whether the ratio of the number of vertices in the first area of the target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes. The method according to claim 1 or 2, wherein the first flag includes at least one of the following: Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected; Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes; Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis. The method according to any one of claims 1 to 4, wherein decoding the first code stream to obtain the first flag comprises: Decoding the first code stream to obtain flag 1; If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, decoding the flag 2 corresponding to the first axis; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, decoding the flag 3 corresponding to the first axis; Decode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, decode the flag 3 corresponding to the second axis; And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; decode the mark 3 corresponding to the third axis. The method of claim 1, wherein processing vertices in the geometric structure according to the first flag comprises: Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag; Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body; The vertex is processed according to the type of the vertex. The method according to claim 6, wherein determining the type of vertices in the geometric structure based on the original point cloud distribution information of the sub-geometric body comprises at least one of the following: In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs; In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric body of the first vertical plane, then the vertex is determined to be a second type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located; In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices. The method according to claim 6 or 7, wherein processing the vertex according to the type of the vertex comprises at least one of the following: Delete the first type of vertex; The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located. The method according to claim 1, further comprising: The second code stream is decoded to obtain a second flag, where the second flag is used to indicate whether the geometric reconstruction technology is enabled or not. The method according to claim 1 or 9, wherein the method further comprises: Determine that the vertices in the geometric structure corresponding to the Trisoup node meet the first condition; The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold. The method according to claim 1, wherein reconstructing the point cloud using the processed vertices comprises: Determine the position of the centroid vertex after the offset based on the processed vertex; Decode the third code stream and determine the face vertices of the Trisoup node; constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices; Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud. A geometric reconstruction method, comprising: The encoding end encodes the first flag to obtain a first code stream, where the first flag is used to indicate original point cloud distribution information in the geometric structure corresponding to the Trisoup node; The encoding end processes the vertices in the geometric structure according to the first flag; The encoder reconstructs the point cloud using the processed vertices. The method according to claim 12, wherein the method further comprises: Marking original point cloud distribution information of sub-geometric bodies corresponding to child nodes of the Trisoup node according to original point cloud distribution information within the geometric structure corresponding to the Trisoup node, where the sub-geometric bodies are obtained by dividing the geometric structure; The first flag is determined according to the original point cloud distribution information of the sub-geometric body and the vertex existence flag of the edge of the geometric structure. The method according to claim 12 or 13, wherein the first flag includes at least one of the following: Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected; Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes; Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis. The method according to any one of claims 12 to 14, wherein encoding the first flag comprises: Coding mark 1; If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, the flag 2 corresponding to the first axis is encoded; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, the flag 3 corresponding to the first axis is encoded; Encode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, then encode the flag 3 corresponding to the second axis; And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; encode the mark 3 corresponding to the third axis. The method according to any one of claims 12 to 15, wherein the method further comprises: determining a context of the first marker; The step of encoding the first flag to obtain a first code stream includes: The first flag is encoded according to the context to obtain a first code stream. The method of claim 16, wherein determining the context of the first marker comprises: Determining the context of the first marker based on vertex distribution information within the geometric structure corresponding to the Trisoup node; The context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes. The method of claim 12, wherein processing vertices in the geometric structure according to the first flag comprises: Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag; Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body; The vertex is processed according to the type of the vertex. The method according to claim 18, wherein determining the type of vertices in the geometric structure based on the original point cloud distribution information of the sub-geometric body comprises at least one of the following: In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs; In the geometric structure, if an original point cloud does not exist in a sub-geometric volume within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric volume of the first vertical plane, then the vertex is determined to be a second-type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located; In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices. The method according to claim 18 or 19, wherein processing the vertex according to the type of the vertex comprises at least one of the following: Delete the first type of vertex; The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located. The method according to claim 12, wherein the method further comprises: The second flag is encoded into a second code stream, where the second flag is used to indicate whether to enable or not enable the geometric reconstruction technology. The method according to claim 12 or 21, wherein the method further comprises: Determine that the vertices in the geometric structure corresponding to the Trisoup node meet the first condition; The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold. The method according to claim 12, wherein reconstructing the point cloud using the processed vertices comprises: Determine the position of the centroid vertex after the offset based on the processed vertex; Determining face vertices for the Trisoup node, and encoding existence information of the face vertices to obtain a third code stream; constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices; Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud. A geometric reconstruction device, comprising: A first decoding module is configured to decode the first code stream to obtain a first flag, where the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node; a first processing module, configured to process vertices in the geometric structure according to the first flag; The second processing module is used to reconstruct the point cloud using the processed vertices. The apparatus according to claim 24, wherein the apparatus further comprises: A first determination module is used to determine the context according to vertex distribution information in the geometric structure corresponding to the Trisoup node; The first decoding module is specifically configured to decode the first code stream according to the context to obtain a first flag. The device according to claim 25, wherein the context is used to indicate whether the ratio of the number of vertices in the first area of the target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes. The apparatus according to claim 24 or 25, wherein the first flag comprises at least one of the following: Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected; Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes; Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis. The apparatus according to any one of claims 24 to 27, wherein the first decoding module is specifically configured to: Decoding the first code stream to obtain flag 1; If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, decoding the flag 2 corresponding to the first axis; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, decoding the flag 3 corresponding to the first axis; Decode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, decode the flag 3 corresponding to the second axis; And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; decode the mark 3 corresponding to the third axis. The apparatus according to claim 24, wherein the first processing module is specifically configured to: Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag; Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body; The vertex is processed according to the type of the vertex. The apparatus according to claim 29, wherein the first processing module is specifically configured to perform at least one of the following: In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs; In the geometric structure, if an original point cloud does not exist in a sub-geometric volume within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric volume of the first vertical plane, then the vertex is determined to be a second-type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located; In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices. The apparatus according to claim 29 or 30, wherein the first processing module is specifically configured to perform at least one of the following: Delete the first type of vertex; The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located. The apparatus according to claim 24, wherein the apparatus further comprises: The second decoding module is used to decode the second code stream to obtain a second flag, where the second flag is used to indicate whether to enable or disable the geometric reconstruction technology. The apparatus according to claim 24 or 32, wherein the apparatus further comprises: A second determination module is used to determine whether a vertex in the geometric structure corresponding to the Trisoup node satisfies a first condition; The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold. The device according to claim 24, wherein the second processing module is specifically configured to Determine the position of the centroid vertex after the offset based on the processed vertex; Decode the third code stream and determine the face vertices of the Trisoup node; constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices; Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud. A geometric reconstruction device, comprising: A first encoding module, configured to encode a first flag to obtain a first code stream, wherein the first flag is used to indicate original point cloud distribution information in a geometric structure corresponding to a Trisoup node; a third processing module, configured to process vertices in the geometric structure according to the first flag; The fourth processing module is used to reconstruct the point cloud using the processed vertices. The apparatus according to claim 35, further comprising a third determining module, specifically configured to: Marking original point cloud distribution information of sub-geometric bodies corresponding to child nodes of the Trisoup node according to original point cloud distribution information within the geometric structure corresponding to the Trisoup node, where the sub-geometric bodies are obtained by dividing the geometric structure; The first flag is determined according to the original point cloud distribution information of the sub-geometric body and the vertex existence flag of the edge of the geometric structure. The apparatus according to claim 35 or 36, wherein the first flag comprises at least one of the following: Flag 1: used to indicate whether there are vertices in the geometric structure that need to be corrected; Flag 2: used to indicate whether the dimension value of the vertex in the target axis needs to be corrected, and the target axis is any one of the three axes; Flag 3: used to indicate the correction direction when the dimension value of the vertex in the target axis needs to be corrected, and the correction direction includes the positive direction or negative direction of the target axis. The apparatus according to any one of claims 35 to 37, wherein the first encoding module is specifically configured to: Coding mark 1; If the flag 1 indicates that there is a vertex that needs to be corrected in the geometric structure, the flag 2 corresponding to the first axis is encoded; if the flag 2 corresponding to the first axis indicates that the dimension value of the vertex in the first axis needs to be corrected, the flag 3 corresponding to the first axis is encoded; Encode the flag 2 corresponding to the second axis; if the flag 2 corresponding to the second axis indicates that the dimension value of the vertex in the second axis needs to be corrected, then encode the flag 3 corresponding to the second axis; And/or, if the mark 2 corresponding to the first axis indicates that the dimensional value of the vertex in the first axis does not need to be corrected, and the mark 2 corresponding to the second axis indicates that the dimensional value of the vertex in the second axis does not need to be corrected, then determine that the mark 2 corresponding to the third axis indicates that the dimensional value of the vertex in the third axis needs to be corrected; encode the mark 3 corresponding to the third axis. The device according to any one of claims 35 to 38, wherein the device further comprises: a fourth determining module, configured to determine a context of the first sign; The first encoding module is specifically configured to encode the first flag according to the context to obtain a first code stream. The apparatus according to claim 39, wherein the fourth determining module is specifically configured to: Determining the context of the first marker based on vertex distribution information within the geometric structure corresponding to the Trisoup node; The context is used to indicate whether a ratio of the number of vertices in a first region of a target axis to the total number of vertices is greater than or equal to a first threshold; the target axis is any one of the three axes. The apparatus according to claim 35, wherein the third processing module is specifically configured to: Marking original point cloud distribution information of the sub-geometric body corresponding to the child node of the Trisoup node according to the first flag; Determining the types of vertices in the geometric structure according to the original point cloud distribution information of the sub-geometric body; The vertex is processed according to the type of the vertex. The apparatus according to claim 41, wherein the third processing module is specifically configured to perform at least one of the following: In the geometric structure, if an original point cloud does not exist in a sub-geometric body within a first plane to which the edge where the vertex is located belongs, then the vertex is determined to be a first type vertex, and the first plane is any plane to which the edge where the vertex is located belongs; In the geometric structure, if an original point cloud does not exist in a sub-geometric volume within a first vertical plane of the edge where the vertex is located, and the vertex is in the sub-geometric volume of the first vertical plane, then the vertex is determined to be a second-type vertex, and the first vertical plane is any vertical plane of the edge where the vertex is located; In the geometric structure, other vertices except the first type vertices and the second type vertices are determined to be third type vertices. The apparatus according to claim 41 or 42, wherein the third processing module is specifically configured to perform at least one of the following: Delete the first type of vertex; The second-type vertex is corrected to be the midpoint of the edge where the second-type vertex is located. The apparatus according to claim 35, wherein the apparatus further comprises: The second encoding module is used to encode a second flag into a second code stream, where the second flag is used to indicate whether to enable or disable the geometric reconstruction technology. The apparatus according to claim 35 or 44, wherein the apparatus further comprises: A fifth determining module, configured to determine whether a vertex in the geometric structure corresponding to the Trisoup node satisfies a first condition; The first condition includes: the total number of vertices is greater than or equal to a second threshold, and the ratio of the number of vertices in the second region in any axis to the total number of vertices is greater than or equal to a third threshold. The apparatus according to claim 35, wherein the fourth processing module is specifically configured to: Determine the position of the centroid vertex after the offset based on the processed vertex; Determining face vertices for the Trisoup node, and encoding existence information of the face vertices to obtain a third code stream; constructing a triangular facet based on the vertices in the geometric structure, the offset centroid vertex position, and the face vertices; Ray tracing sampling is performed on the triangular facets to obtain a reconstructed point cloud. An electronic device comprises a processor and a memory, wherein the memory stores a program or instruction that can be run on the processor, and when the program or instruction is executed by the processor, the steps of the geometric reconstruction method according to any one of claims 1 to 11 are implemented, or the steps of the geometric reconstruction method according to claims 12 to 23 are implemented. A readable storage medium storing a program or instruction, wherein the program or instruction, when executed by a processor, implements the geometric reconstruction method according to any one of claims 1 to 11, or implements the steps of the geometric reconstruction method according to any one of claims 12 to 23. A chip comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is configured to run a program or instruction to implement the steps of the method according to any one of claims 1 to 11, or to implement the steps of the method according to claims 12 to 23. A computer program product comprises computer instructions, wherein when the computer instructions are executed by a processor, the steps of the method according to any one of claims 1 to 11 are implemented, or the steps of the method according to claims 12 to 23 are implemented.