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WO1993008537A1 - Procede et circuit de suppression de points d'image caches - Google Patents

Procede et circuit de suppression de points d'image caches Download PDF

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Publication number
WO1993008537A1
WO1993008537A1 PCT/DE1992/000881 DE9200881W WO9308537A1 WO 1993008537 A1 WO1993008537 A1 WO 1993008537A1 DE 9200881 W DE9200881 W DE 9200881W WO 9308537 A1 WO9308537 A1 WO 9308537A1
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WO
WIPO (PCT)
Prior art keywords
image
memory
picture
values
counter
Prior art date
Application number
PCT/DE1992/000881
Other languages
German (de)
English (en)
Inventor
Martin Cobernuss
Herbert RÜSSELER
Original Assignee
Gesellschaft Für Mathematik Und Datenverarbeitung Mbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gesellschaft Für Mathematik Und Datenverarbeitung Mbh filed Critical Gesellschaft Für Mathematik Und Datenverarbeitung Mbh
Publication of WO1993008537A1 publication Critical patent/WO1993008537A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T15/00—3D [Three Dimensional] image rendering
    • G06T15/10—Geometric effects
    • G06T15/40—Hidden part removal
    • G06T15/405—Hidden part removal using Z-buffer

Definitions

  • the invention relates to a method and a circuit arrangement for carrying out processes that take place in a raster graphics system when comparing z-coordinate values to suppress hidden pixels.
  • the invention is based on the problem of reducing waiting times which occur during a picture change and which are perceived as annoying especially in real-time animations and which can be attributed to the fact that the Z memory has so far been deleted and reinitialized with each picture change sieren is. It should also be borne in mind that when the resolution of a vision system is increased, the storage capacities and thus the deletion and initialization times, that is to say the waiting times for image changes, increase disproportionately.
  • the mode of operation of the Z algorithm is based on a comparison operation of all generated Z values with the corresponding Z values from the Z memory.
  • the Z values read out must at be relevant to the image in question.
  • the deletion phases customary up to now therefore delete all entries from the previous image and thus ensure correct comparison values.
  • this effect can also be achieved with the help of a clear assignment of the Z values entered in the Z memory to the respective image.
  • the Z values of the new image points are only compared with the read Z values if they belong to the current image.
  • the generated Z value can be entered immediately in the Z memory and the pixel can be displayed, since no pixel that belongs to the current image has yet been generated at this position.
  • the pixels can be assigned to the respective image with the aid of an image counter and an image number memory which records the current image number for each pixel. If there a counter reading is assigned to the current picture, which the picture number memory does not contain in relation to the non-current pictures, then all picture points which do not belong to the current picture can be clearly identified and excluded from a Z comparison operation.
  • Figure 1 the flow diagram of the method according to the invention
  • Figure 2 is a block diagram of a raster graphics system, with integration of the Z memory in the vision system
  • Figure 3 is a block diagram of a hardware implementation of the
  • Figure 4 a 2D representation of several overlapping objects
  • Figure 5 the flow diagram of a conventional Z algorithm.
  • the method according to the invention runs as follows with an image counter and an image number memory in cooperation with a conventional Z memory (FIG. 1): after switching on, the image number memory is initialized with the initial value of the image counter, for example "0" (Step 6). The Z memory is not initialized or deleted! The frame counter is then incremented (step 7). The image counter reading indicates the sequential number of the image currently being generated. These operations must be carried out once after each switch on or reset.
  • the genes- The image points of an image can now begin. The end of image generation and the beginning of a new image is indicated by a central signal or by an additional marker at each pixel.
  • the image counter reading is read from the image number memory for each pixel generated and compared with the current image counter reading (step 8). If both image numbers are the same, there is already a pixel in this position that belongs to the current image, and a Z comparison must be carried out (step 9). Depending on the Z comparison, the old Z value is replaced by the new Z value and the image point is displayed (step 10), or the old Z value and thus also the old image point are retained. If the picture counter reading from the picture number memory is different from the current picture counter reading, there is still no picture point of the current picture at this position and consequently no Z comparison is necessary. The Z value of the new pixel is written into the Z memory and the pixel is displayed (step 10).
  • the current image counter status is entered in the image number memory for this pixel (step 11). This shows that this position is occupied by a pixel of the current image. All pixels are processed in this way. These processes function as long as only counter readings that are different from the current picture counter reading are noted in the picture number memory, based on the non-current pictures.
  • Fmax (2 exp n) -l images of an image sequence can be distinguished. Image "0" with the image counter reading of, for example, also "0" corresponds to the initialization state after switching on.
  • the image counter reading (“1") is now compared with the content of the image number memory ("0" or "1").
  • Case - - b In order to distribute the memory bandwidth as evenly as possible, it is advantageous to divide the deletion process. After each picture, 1 / Fmax of the entire picture number memory is continuously written with the current picture counter status (case b, step 13) and only then is the picture counter modulo Fmax +1 incremented (step 14).
  • the frame counter length is specified with n
  • Fmax (2 exp n) -1.
  • the 1 / Fmax part of the image number memory is written continuously. The time it takes to delete per picture is reduced to 1 / Fmax of the complete deletion time.
  • the raster graphics system with real time properties shown as a block diagram in FIG. 2 is suitable for successfully implementing the solution according to the invention.
  • the visualization processes necessary for image generation are supported by conventional specific hardware.
  • the visualization is carried out by a pipeline, consisting of a geometry processor 15 (affine and perspective transformations, backfacing, 3D clip process), a renderer 16 (calculation of all pixels of a surface, surface shading according to Phong), the Z Memory 17 (elimination of the hidden pixels), and from a 2D subsystem 18 including image repetition memory and display device 22.
  • the Z memory 17 is an independent unit within the visualization pipeline, between the scan converter - renderer 16 - and the image repetition memory 18.
  • the Z memory 17 evaluates the Z values 19 of the pixels generated and conducts them if they are successful Z comparison the x, y coordinates 20 as addresses. and the color value 21 of the pixels to the image repetition memory 18.
  • a control unit 26 carries out each Z comparison in accordance with the sequence shown in FIG. 1 (case b). However, the sequence in embodiments of the invention is summarized that BZ. old from the picture number memory 24 and Z. old from the Z memory 17 can be read simultaneously. Since a picture number is compared to 4-bit in picture number comparator 25 significantly faster than the 24-bit Z comparison in Z-value comparator 29, in many cases the result of the 24-bit Z comparison does not have to be be waited for. Furthermore, the shallower memory of frame number memory 24 allows the use of fast static RAMs, so that the average time for a memory cycle including the Z comparison is considerably reduced.
  • the 1 / Fmax part of the image number memory 24 is written by the image change signal 27 with the current image counter reading.
  • the control unit 26 generates the delete addresses 28 required for this for the picture number memory 24.
  • the picture counter 23 is then incremented and the generation of the new picture can begin.
  • the proportion of the deletion time in the total time for the generation of an image is only approx. 1.5% if 10 images are generated per second; This means that approximately 98.5% of the time is available for the Z comparison.
  • the comparison of the new Z values with the old Z values from the Z memory is only correct if the old Z value read out is valid. In two cases, however, this is not the case: a) after switching on and b) when generating a new image. After switching on, the Z memory contains only random values, so that a correct comparison with the Z values of the pixels of the first image is not possible. The entire Z memory must therefore be initialized.
  • a customary method for initializing the Z memory consists in writing an initialization value which does not belong to the range of values of the Z values and which always leads to an exchange.
  • Z.min or Z.max is usually selected depending on the coordinate origin.
  • the initialization phases represent a not inconsiderable portion of the total time for the generation of an image, in particular for viewing devices with high resolution with the necessary size of the Z memory of approx. 4 Mbyte (1280 x 1024 pixels a 24 bit)
  • Real-time animation systems reduce the initialization phases and the time available for building an image. This reduces the complexity of the images that can be represented and the overall system performance is reduced. A reduction or saving in the initialization phases to which the invention relates therefore makes a not insignificant contribution to the increase in the overall system performance.
  • Z memory systems based on dynamic RAMs require approx. 15 ms to 20 ms for the initialization.
  • the available image construction time is reduced from 100 ms to 8C ms to 85 ms, which corresponds to 15% to 20% of the total time.
  • Video RAMs represent an alternative. These are dynamic RAMs in which, among other things, an entire row of the internal memory matrix of, for example, 256 memory cells can be written in one memory cycle. If the Z memory is built up with video RAMs, the deletion times are 20 times less than those of the method according to the invention. However, another fact has a negative effect: Video RAMs currently have cycle times of 180 ns to 200 ns when accessing memory compared to 110 ns to 130 ns of normal dynamic RAMs. Based on a memory bank, the maximum memory bandwidth is 5.5 M image points / s Video RAMs at 9 M image points / s with dynamic RAMs (READ or WRITE, not RMWl). This corresponds to a performance difference of 50% to 60%, so that video RAMs are not a serious alternative to dRAMs, despite their favorable deletion times.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Geometry (AREA)
  • Computer Graphics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Image Generation (AREA)
  • Controls And Circuits For Display Device (AREA)

Abstract

Dans des systèmes graphiques à trames, on utilise, pour supprimer des points d'image cachés, une mémoire (17) des coordonnées Z et les valeurs correspondantes des coordonnées Z sont comparées dans un comparateur (29). L'inconvénient de ce système consiste dans le fait qu'il faut initialiser ou effacer toute la mémoire (17) de coordonnées Z pour que seules les valeurs valables des coordonnées Z de l'image actuelle soient comparées. Les phases d'initialisation requises durent longtemps, réduisent le temps disponible pour construire l'image et dérangent surtout dans des séquences d'images. Afin d'augmenter la vitesse de changement d'images, les valeurs des coordonnées Z enregistrées dans la mémoire (17) de coordonnées Z sont attribuées de manière permanente à l'image correspondante par un compteur d'images (23) et par une mémoire (24) des numéros d'images. Les coordonnées Z ne sont comparées que lorsque les valeurs des coordonnées Z lues dans la mémoire (17) de coordonnées Z appartiennent à l'image actuelle. Autrement, les valeurs générées des coordonnées Z sont immédiatement enregistrées dans la mémoire (17) des coordonnées Z et les points d'images correspondants sont représentés. En fonction du nombre d'images distinctes, la mémoire (17) des coordonnées Z ne doit être initialisée ou effacée que lorsque la largeur de la bande disponible de numéros d'image est dépassée.
PCT/DE1992/000881 1991-10-17 1992-10-16 Procede et circuit de suppression de points d'image caches WO1993008537A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4134576.2 1991-10-17
DE19914134576 DE4134576A1 (de) 1991-10-17 1991-10-17 Verfahren und schaltungsanordnung zur unterdrueckung verdeckter bildpunkte

Publications (1)

Publication Number Publication Date
WO1993008537A1 true WO1993008537A1 (fr) 1993-04-29

Family

ID=6442991

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE1992/000881 WO1993008537A1 (fr) 1991-10-17 1992-10-16 Procede et circuit de suppression de points d'image caches

Country Status (2)

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DE (1) DE4134576A1 (fr)
WO (1) WO1993008537A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045789A (en) * 1975-10-29 1977-08-30 Atari, Inc. Animated video image display system and method
EP0403121A2 (fr) * 1989-06-16 1990-12-19 International Business Machines Corporation Production d'images animées par ordinateur

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045789A (en) * 1975-10-29 1977-08-30 Atari, Inc. Animated video image display system and method
EP0403121A2 (fr) * 1989-06-16 1990-12-19 International Business Machines Corporation Production d'images animées par ordinateur

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
EUROGRAPHICS 89 4. September 1989, AMSTERDAM Seiten 51 - 61 HAU XU E.A. 'ACCELARATED RADIOSITY METHOD FOR COMPLEX ENVIRONMENT' *

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DE4134576A1 (de) 1993-04-22

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