WO2019021393A1 - Distance measurement device and distance measurement method - Google Patents

Abstract

In the present invention, a ship detection unit (12) detects image data for another ship from wide-angle image data and calculates the coordinates of the other ship. An approach determination unit (13) determines whether the other ship detected by the ship detection unit (12) is moving toward or away from a host ship. A coordinate calculation unit (15) calculates the coordinates in telephoto image data of another ship that has been determined to be approaching by the approach determination unit (13). A triangulation unit (16) calculates the distance between the other ship and the host ship using the coordinates calculated by the ship detection unit (12) and the coordinate calculation unit (15).

Description

Distance measuring device and distance measuring method

The present invention relates to a distance measuring device and a distance measuring method for measuring the distance between ships.

An object photographing apparatus according to Patent Document 1 calculates the position of a common object photographed on the basis of two images of different photographing magnifications photographed by a wide-angle camera and a telephoto camera.

JP 2004-364212 A

The object imaging device according to Patent Document 1 is a method of simply calculating the distance from two cameras to the same object in the field of view, and is merely an application of triangulation. Since it takes some processing time to calculate the distance to the target by linking two cameras, if there are a large number of other ships around the ship, two cameras will be linked for each other ship It is not realistic to calculate the distance. Therefore, there has been a problem that the conventional object imaging device is not suitable for measuring the distance between ships sailing on the ocean.

The present invention has been made to solve the above-described problems, and it is an object of the present invention to measure the distance to another ship that may collide with the ship using image data of a wide-angle camera and a telephoto camera. I assume.

The distance measuring apparatus according to the present invention detects a wide-angle image data of another ship from the wide-angle image data and a wide-angle image acquisition unit that acquires wide-angle image data captured by a wide-angle camera installed in the ship. Compare the latest image data of the other ship detected by the ship detection unit with the previous image data to determine whether the other ship is approaching or leaving its own ship by calculating the coordinates of the other ship at Approach determination unit, and a telephoto image acquisition unit that turns the telephoto camera installed on the ship toward the other vessels determined to be approaching by the approach determination unit, and acquires telephoto image data captured by the telephoto camera A coordinate calculation unit for calculating coordinates in the telephoto image data of another ship determined to be approaching by the approach determination unit, and each coordinate calculated by the ship detection unit and the coordinate calculation unit Used, in which and a triangulation unit for calculating the principle distance triangulation with other ships and ship it is determined in closer proximity determination unit.

According to the present invention, the other ship approaching the ship is detected using the wide-angle image data taken by the wide-angle camera, and from the ship itself using the wide-angle image data and the telephoto image data taken by the telephoto camera. Since the distance to another ship is calculated, it is possible to measure the distance to another ship that may collide with the own ship using the image data of the wide-angle camera and the telephoto camera.

FIG. 1 is a block diagram showing an example of the configuration of a distance measurement device according to Embodiment 1. 5 is a flowchart showing an operation example of the distance measuring device according to the first embodiment. 5 is a diagram showing an example of wide-angle image data in Embodiment 1. FIG. FIG. 7 is a diagram showing where a small region r1 in wide-angle image data at time t0 is located in the past wide-angle image data from time t1 to t3. FIG. 7 is a diagram for explaining an approach determination method by the approach determination unit of the first embodiment. FIG. 5 is a diagram for explaining turning control of a telephoto camera by the telephoto image acquisition unit of the first embodiment. It is a figure which shows the example of the wide angle image data which the wide angle camera and the telephoto camera imaged in the condition of FIG. 7A and FIG. 7B and FIG. 6, and telephoto image data. FIG. 7 is a diagram for explaining a template matching method by the coordinate calculation unit of the first embodiment. FIG. 5 is a diagram for explaining triangulation by a triangulation unit of the first embodiment. FIG. 7 is a block diagram showing an example of configuration of a distance measuring device according to a second embodiment. 11A and 11B are diagrams showing an example of the hardware configuration of the distance measurement device according to each embodiment.

Hereinafter, in order to explain the present invention in more detail, a mode for carrying out the present invention will be described according to the attached drawings.
Embodiment 1
FIG. 1 is a block diagram showing a configuration example of the distance measuring device 10 according to the first embodiment. The distance measuring device 10 is mounted on the own ship, measures the distance to another ship approaching the own ship, and is connected to the wide-angle camera 20, the telephoto camera 30, and the display 40 mounted on the own ship. Ru. The distance measurement device 10 includes a wide angle image acquisition unit 11, a ship detection unit 12, an approach determination unit 13, a telephoto image acquisition unit 14, a coordinate calculation unit 15, and a triangulation unit 16.

The wide-angle camera 20 is a fixed camera that captures an image of the surroundings of the ship with a wide-angle lens. The wide-angle camera 20 outputs the captured image data to the wide-angle image acquisition unit 11. Note that if it is not possible to image the entire periphery of the ship at the angle of view of one wide-angle camera 20, the entire periphery of the ship may be imaged by a plurality of wide-angle cameras 20.
Hereinafter, image data captured by the wide-angle camera 20 will be referred to as “wide-angle image data”.

The telephoto camera 30 has an actuator 31 that turns the telephoto camera 30. The actuator 31 turns the telephoto camera 30 in accordance with the turning instruction of the telephoto image acquisition unit 14. The telephoto camera 30 captures the direction of the turning by the actuator 31 and instructed by the telephoto image acquisition unit 14 with the telephoto lens, and outputs the image data to the telephoto image acquisition unit 14.
Hereinafter, image data captured by the telephoto camera 30 will be referred to as “telephoto image data”.

The display 40 displays the distance between the own ship and another ship measured by the distance measurement device 10, an index of collision danger of the own ship and the other ship, and the like.

Next, an operation example of the distance measuring device 10 according to the first embodiment will be described.
FIG. 2 is a flowchart showing an operation example of the distance measuring device 10 according to the first embodiment. The distance measuring device 10 repeats the operation shown in the flowchart of FIG.

In step ST11, the wide-angle image acquisition unit 11 acquires wide-angle image data captured by the wide-angle camera 20 and outputs the wide-angle image data to the ship detection unit 12.

FIG. 3 is a diagram showing an example of wide-angle image data in the first embodiment. In FIG. 3, wide-angle image data captured at time t0, wide-angle image data captured at time t1, wide-angle image data captured at time t2, and wide-angle image data captured at time t3 are illustrated. The time is sequentially traced back from time t0, the wide-angle image data at time t0 is the latest, and the wide-angle image data at time t3 is the most recent. In each wide-angle image data, it is confirmed that there is another ship near the center of the image and the other ship is moving to the right of the image. In addition, what is reflected on the left side of other ships is a breakwater.

In step ST12, the ship detection unit 12 detects image data of another ship from the wide-angle image data and outputs the same to the approach determination unit 13, and calculates coordinates of the other ship in the wide-angle image data to the triangulation unit 16. Output.

The ship detection unit 12 divides the latest wide-angle image data at time t0 into a plurality of small areas, checks where each small area is in the past wide-angle image data from time t1 to t3, and The other ship is detected based on the movement at time t1 to t3.
FIG. 4 is a diagram showing where the small area r1 in the wide-angle image data at time t0 is located in the past wide-angle image data from time t1 to t3. Other ships have the feature of moving at substantially constant speed in almost the same direction in the image in a short time. The ship detection unit 12 detects another ship using this feature. In FIG. 4, the small area r1 moves at a substantially constant speed to the right in the wide-angle image data from time t1 to t3, so the small area r1 is detected as another ship.

Note that where in the wide-angle image data at another time the small region r1 in the wide-angle image data at time t0 can be calculated by template matching. Template matching is a well-known technique, so detailed description will be omitted.
Alternatively, the ship detection unit 12 may detect another ship based on machine learning using an artificial neural network or the like. A method of causing an artificial neural network to learn a specific object and identify the object is described in, for example, Japanese Patent No. 6125137.

In step ST13, the approach determination unit 13 compares the latest image data of another ship detected by the ship detection unit 12 with the past image data to determine whether the other ship is approaching or leaving the ship.

For example, the approach determination unit 13 enlarges and reduces the latest image data of another ship detected by the ship detection unit 12 to generate enlarged image data and reduced image data, and the enlarged image data and the reduced image data The correlation coefficient with the past image data is calculated to determine the approach and departure of other ships.

FIG. 5 is a diagram for explaining the approach determination method by the approach determination unit 13 of the first embodiment. The approach determination unit 13 cuts out image data of another ship from the wide-angle image data at time t0 based on the coordinates of the other ship detected by the ship detection unit 12, and sets the image data as a template image r10. Then, the approach determination unit 13 generates an image array consisting of a total of nine types of image data r10 to r18 obtained by enlarging and reducing the template image r10 in the horizontal and vertical directions. This image array includes the template image r10 before enlargement and reduction. The approach determination unit 13 performs template matching on the past wide-angle image data at time t1 using each of the image data r10 to r18 as a template, and the correlation coefficient between each template and the wide-angle image data at time t1. Calculate The approach determination unit 13 determines that another ship is approaching when the correlation coefficient between any of the image data r16 to r18 enlarged in the vertical direction and the wide-angle image data at time t1 becomes maximum. On the other hand, when the correlation coefficient between any of the image data r11 to r13 reduced in the vertical direction and the wide-angle image data at time t1 becomes maximum, the approach determination unit 13 determines that the other vessel is leaving. . The image data r11, r14, r16 reduced in the horizontal direction and the image data r13, r15, r18 expanded in the horizontal direction as an image array are required because other ships approach or leave the ship. Regardless of the above, it is to determine the approach and departure when the horizontal length of another ship changes due to the change of the direction of the other ship viewed from the own ship.

Although FIG. 5 describes an example in which the approach determination unit 13 uses a 3 × 3 image array, depending on the time difference between the past wide-angle image data and the latest wide-angle image data or the distance from one ship to another Image arrays of other numbers of images may be used, such as 5 × 5. The approach determination unit 13 uses, for example, the approximate distance calculated by the distance estimation unit 17 of the second embodiment described later, as the distance from the own ship to another ship.
The approach determination unit 13 may not only perform template matching between the image array and the wide-angle image data at time t1, but also perform template matching with a plurality of past wide-angle image data. In that case, the proximity determination unit 13 can obtain a correlation coefficient with higher certainty by statistically processing the results of the plurality of template matching.

In step ST14, when the approach determination unit 13 determines that another ship is approaching (YES in step ST14), the determination result is output to the telephoto image acquisition unit 14 and the process proceeds to step ST15, and the other ship is disconnected. If it is determined to be medium (step ST14 “NO”), there is no possibility that another ship collides with the own ship, so the operation shown in the flowchart of FIG. 2 is ended.

In step ST15, the telephoto image acquisition unit 14 instructs the actuator 31 to turn the telephoto camera 30 toward another ship determined to be approaching by the approach determination unit 13, and telephoto image data captured by the telephoto camera 30. Are obtained and output to the coordinate calculation unit 15.

FIG. 6 is a diagram for explaining turning control of the telephoto camera 30 by the telephoto image acquisition unit 14 according to the first embodiment. 6, the position cw of the wide-angle camera 20 mounted on the ship, the angle of view 20a of the wide-angle camera 20, the position cz of the telephoto camera 30 mounted on the ship, the angle of view 30a of the telephoto camera 30, the approach determination unit The telephoto camera 30 is viewed from the position cw of the wide-angle camera 20 when the imaginary straight line passing through the position s of the other ship determined to be approaching by 13 and the position cw of the wide-angle camera 20 and the position cz of the telephoto camera 30 The length L of the baseline to the position cz of is indicated. The telephoto image acquisition unit 14 instructs the actuator 31 to make a turn so that the other camera determined to be approaching by the approach determination unit 13 with the telephoto camera 30, and causes the telephoto camera to turn in the same direction as the wide-angle camera 20. Control the direction of 30.

FIG. 7A is a diagram showing an example of wide-angle image data captured by the wide-angle camera 20 in the situation of FIG. FIG. 7B is a diagram showing an example of telephoto image data captured by the telephoto camera 30 in the situation of FIG.

In FIG. 6, the telephoto image acquisition unit 14 sets the direction of the telephoto camera 30 so that the wide-angle camera 20 and the telephoto camera 30 have the same orientation, and instructs the actuator 31 to turn. It is not a thing. For example, after setting the direction of the telephoto camera 30 so that the wide-angle camera 20 and the telephoto camera 30 have the same orientation, the telephoto image acquisition unit 14 ensures that other ships are within the angle of view of the telephoto camera 30. The direction of the telephoto camera 30 may be finely adjusted based on the coordinates of another ship in the wide-angle image data calculated by the ship detection unit 12. Also, for example, the telephoto image acquisition unit 14 sets the direction of the telephoto camera 30 based on the directions of other ships with respect to the wide-angle camera 20 and the approximate distance calculated by the distance estimation unit 17 of the second embodiment described later. May be

In step ST16, the coordinate calculation unit 15 calculates the coordinates in the telephoto image data of the other ship determined to be approaching by the approach determination unit 13 and outputs the calculated coordinates to the triangulation unit 16.

FIG. 8 is a diagram for explaining a template matching method by the coordinate calculation unit 15 according to the first embodiment.
The coordinate calculation unit 15 first enlarges the image data of the other ship in the wide-angle image data so as to match the size of the image data of the other ship in the telephoto image data. The magnification ratio is determined by the ratio of the focal lengths of the wide-angle camera 20 and the telephoto camera 30. The image data which expanded the image data of the other ship in wide-angle image data is called "wide-angle ship image data." Subsequently, the coordinate calculation unit 15 performs template matching on the telephoto image data B in the direction of the arrow by using the wide-angle vessel image data A as a template, thereby specifying the other vessels in the telephoto image data B and coordinates. Calculate

In step ST17, using the coordinates calculated by the ship detection unit 12 and the coordinate calculation unit 15, the triangulation unit 16 uses the coordinates determined by the approach determination unit 13 to triangle the distance between the other ship and its own ship. Calculated according to the principle of surveying. Then, the triangulation unit 16 outputs and displays information indicating the distance from the own ship to another ship on the display 40.

FIG. 9 is a diagram for explaining triangulation by the triangulation unit 16 of the first embodiment.
The triangulation unit 16 uses the coordinates of the other ship in the wide-angle image data calculated by the ship detection unit 12 to calculate the angle α between the base line with the position cw of the wide-angle camera 20 as the vertex and the position s of the other ship. Do. The triangulation unit 16 also uses the coordinates of the other ship in the telephoto image data calculated by the coordinate calculation unit 15 to form an angle β between the base line with the position cz of the telephoto camera 30 as the vertex and the position s of the other ship. Calculate And the triangulation part 16 calculates Formula (1) and obtains the distance d from a base line to the position s of another ship, ie, the distance d of an own ship and another ship.

As described above, the distance measurement device 10 according to the first embodiment includes the wide-angle image acquisition unit 11, the ship detection unit 12, the approach determination unit 13, the telescopic image acquisition unit 14, the coordinate calculation unit 15, and the triangulation unit 16. Prepare. The wide-angle image acquisition unit 11 acquires wide-angle image data captured by the wide-angle camera 20 installed on the ship. The ship detection unit 12 detects image data of another ship from the wide-angle image data and calculates coordinates of the other ship in the wide-angle image data. The approach determination unit 13 compares the latest image data of another ship detected by the ship detection unit 12 with the past image data to determine whether the other ship is approaching or leaving the ship. The telephoto image acquisition unit 14 turns the telephoto camera 30 installed on the own ship toward another ship determined to be approaching by the approach determination unit 13, and acquires telephoto image data captured by the telephoto camera 30. The coordinate calculation unit 15 calculates coordinates in the telescopic image data of another ship determined to be approaching by the approach determination unit 13. The triangulation unit 16 uses the coordinates calculated by the ship detection unit 12 and the coordinate calculation unit 15 to determine the distance between another ship determined to be approaching by the approach determination unit 13 according to the principle of triangulation. calculate. Thereby, it is possible to detect another ship that may collide with the own ship, and measure the distance between the detected other ship and the own ship using the image data of the wide-angle camera 20 and the telephoto camera 30. Therefore, even if it takes some processing time to measure the distance by linking the wide-angle camera 20 and the telephoto camera 30, only the other ships approaching the ship are linked the wide-angle camera 20 and the telephoto camera 30 Since the distance d is measured, it is effective for collision avoidance between another ship and the own ship.

Further, the approach determination unit 13 according to the first embodiment enlarges and reduces the latest image data of another ship detected by the ship detection unit 12 to generate enlarged image data and reduced image data, and the enlarged image data and reduction The correlation coefficient between the image data and the past image data of the other vessels is calculated to determine the approach and departure of the other vessels. This makes it possible to accurately determine whether another ship is approaching or leaving the ship.

Second Embodiment
FIG. 10 is a block diagram showing a configuration example of the distance measuring device 10 according to the second embodiment. The distance measuring device 10 according to the second embodiment has a configuration in which a distance approximating unit 17 is added to the distance measuring device 10 according to the first embodiment shown in FIG. The parts in FIG. 10 that are the same as or correspond to those in FIG.

The distance approximating unit 17 approximates the distance between the other vessel and the own vessel using the coordinates of the other vessel calculated by the vessel detecting unit 12, and outputs the approximate distance to the telephoto image acquiring unit 14.

　ここで、自船舶は座標（０，０，０）にあり、Ｘ軸の正方向を向いていることとした上で、ｈは海面からの広角カメラ２０の高さ、ｒは地球半径、（ｕ，ｖ）は広角画像データにおける他船舶の座標、（ｕ０，ｖ０）は広角画像データにおける中心座標、ｃは広角カメラ２０の焦点距離、（ω，φ，κ）は広角カメラ２０のローリング角とピッチング角とヨーイング角を示す。 The approximate distance dA is obtained by the equation (2). X, Y, Z in the equation (2) can be obtained by the equations (3), (4) and (5).

Here, assuming that the ship is at coordinates (0, 0, 0) and is oriented in the positive direction of the X axis, h is the height of the wide-angle camera 20 from the sea surface, r is the radius of the earth, u, v) are coordinates of other ships in wide-angle image data, (u0, v0) are central coordinates in wide-angle image data, c is focal length of wide-angle camera 20, (ω, φ, ω) is rolling angle of wide-angle camera 20 And pitching angle and yawing angle.

The telephoto image acquisition unit 14 turns the telephoto camera 30 when the approach determination unit 13 determines that another ship is approaching and the distance estimated by the distance estimation unit 17 is equal to or less than a predetermined threshold. Acquire image data. Moreover, the triangulation part 16 calculates the distance of the own ship and another ship. The threshold is a value given in advance to the telephoto image acquisition unit 14, and is a value for determining whether or not another ship may collide with the own ship.
On the other hand, when the approach determination unit 13 determines that another ship is in the process of being separated, or when the distance estimated by the distance estimation unit 17 is larger than a predetermined threshold value, the telephoto image acquisition unit 14 Do not get. Therefore, the triangulation unit 16 does not calculate the distance between the own ship and another ship. That is, when the other ship is leaving or when the other ship is far, the possibility of the other ship colliding with the own ship is low, and therefore, the distance measurement by the distance measurement device 10 is unnecessary.

As described above, the distance measurement device 10 according to the second embodiment includes the distance estimation unit 17 that approximates the distance between another ship and the own ship using the coordinates of the other ship calculated by the ship detection unit 12. The telephoto image acquisition unit 14 turns the telephoto camera 30 when the approach determination unit 13 determines that another ship is approaching and the distance estimated by the distance estimation unit 17 is equal to or less than a predetermined threshold. Acquire image data. Thereby, the distance measuring device 10 can reduce the processing load without performing the distance measurement of another ship having a low possibility of colliding with the own ship. Even if it takes some processing time to measure the distance by linking the wide-angle camera 20 and the telephoto camera 30, only the other vessels approaching the own vessel with the approximate distance d close to the own vessel being close Since the wide-angle camera 20 and the telephoto camera 30 are linked to measure the distance d, it is further effective for avoiding a collision between another ship and the own ship.

Finally, a hardware configuration example of the distance measuring device 10 according to each embodiment will be described.
11A and 11B are hardware configuration diagrams of the distance measuring device 10 according to each embodiment. The functions of the wide-angle image acquisition unit 11, the ship detection unit 12, the approach determination unit 13, the telephoto image acquisition unit 14, the coordinate calculation unit 15, the triangulation unit 16 and the distance estimation unit 17 in the distance measuring device 10 are realized by processing circuits. Be done. That is, the distance measurement device 10 includes a processing circuit for realizing the above-described functions. The processing circuit may be the processing circuit 100 as dedicated hardware, or may be the processor 102 that executes a program stored in the memory 101. The processing circuit 100 or processor 102, the memory 101, the wide-angle camera 20, the telephoto camera 30, the actuator 31, and the display 40 are electrically connected. Image data captured by the wide-angle camera 20 and the telephoto camera 30 is stored in the memory 101.

As shown in FIG. 11A, when the processing circuit is dedicated hardware, the processing circuit 100 may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application specific integrated circuit (ASIC). , FPGA (Field Programmable Gate Array), or a combination thereof. The functions of the wide-angle image acquisition unit 11, the ship detection unit 12, the approach determination unit 13, the telephoto image acquisition unit 14, the coordinate calculation unit 15, the triangulation unit 16 and the distance estimation unit 17 may be realized by a plurality of processing circuits 100. Alternatively, the functions of the respective units may be collectively realized by one processing circuit 100.

As shown in FIG. 11B, when the processing circuit is the processor 102, the wide-angle image acquisition unit 11, the ship detection unit 12, the approach determination unit 13, the telephoto image acquisition unit 14, the coordinate calculation unit 15, the triangulation unit 16, and the distance estimation Each function of the unit 17 is realized by software, firmware, or a combination of software and firmware. Software or firmware is described as a program and stored in the memory 101. The processor 102 implements the functions of the respective units by reading and executing the program stored in the memory 101. That is, the distance measuring device 10 includes the memory 101 for storing a program which, when executed by the processor 102, results in the steps shown in the flowchart of FIG. Moreover, this program executes the procedure or method of the wide-angle image acquisition unit 11, the ship detection unit 12, the approach determination unit 13, the telephoto image acquisition unit 14, the coordinate calculation unit 15, the triangulation unit 16 and the distance estimation unit 17 on a computer It can be said that it is something that

Here, the processor 102 refers to a central processing unit (CPU), a processing device, an arithmetic device, a microprocessor, a microcomputer, or the like.
The memory 101 may be a nonvolatile or volatile semiconductor memory such as a random access memory (RAM), a read only memory (ROM), an erasable programmable ROM (EPROM), or a flash memory, a hard disk, a flexible disk, or the like. Or an optical disc such as a CD (Compact Disc) or a DVD (Digital Versatile Disc).

The hardware dedicated to a part of the functions of the wide-angle image acquisition unit 11, the ship detection unit 12, the approach determination unit 13, the telephoto image acquisition unit 14, the coordinate calculation unit 15, the triangulation unit 16, and the distance estimation unit 17 And may be partially realized by software or firmware. Thus, the processing circuit in the distance measuring device 10 can realize each of the functions described above by hardware, software, firmware, or a combination thereof.

In the scope of the present invention, free combinations of the respective embodiments, deformation of any component of each embodiment, or omission of any component of each embodiment are possible within the scope of the invention.

Since the distance measuring device according to the present invention measures the distance to another ship approaching the own ship, it is used for a distance measuring device etc. for automatically detecting other ships that may have a collision. Is suitable.

DESCRIPTION OF SYMBOLS 10 distance measurement apparatus, 11 wide angle image acquisition part, 12 ship detection part, 13 approach determination part, 14 telephoto image acquisition part, 15 coordinate calculation part, 16 triangulation part, 17 distance approximation part, 20 wide angle camera, 20a, 30a image Angle, 30 telephoto camera, 31 actuator, 40 display, 100 processing circuit, 101 memory, 102 processor, A wide-angle ship image data, B telephoto image data, cw wide-angle camera position, cz telephoto position, L baseline length , R1 small area, r10 to r18 image data, s position of other ships, time t0 to t3.

Claims (4)

A wide-angle image acquisition unit that acquires wide-angle image data captured by a wide-angle camera installed on the ship;
A ship detection unit that detects image data of another ship from the wide-angle image data and calculates coordinates of the other ship in the wide-angle image data;
An approach determination unit that determines whether the other vessel is approaching or leaving the own vessel by comparing the latest image data of the other vessel detected by the vessel detection unit with the past image data;
A telephoto image acquisition unit that turns a telephoto camera installed on the ship into the other boat that is determined to be approaching by the approach determination unit, and acquires telephoto image data captured by the telephoto camera;
A coordinate calculation unit that calculates coordinates in the telephoto image data of the other ship determined to be approaching by the approach determination unit;
Triangulation that calculates the distance between the other ship determined to be approaching by the approach determination unit using the coordinates detected by the ship detection unit and the coordinate calculation unit according to the principle of triangulation Distance measuring device provided with The approach determination unit enlarges and reduces the latest image data of the other ship detected by the ship detection unit to generate enlarged image data and reduced image data, and the enlarged image data and the reduced image data 2. A distance measuring apparatus according to claim 1, wherein the approach and departure of said another ship are determined by calculating a correlation coefficient with image data of the other ship in the past. The distance estimation unit estimates the distance between the other vessel and the own vessel using the coordinates of the other vessel calculated by the vessel detector.
The telephoto image acquisition unit turns the telephoto camera when it is determined that the other ship is approaching by the approach determination unit and the distance estimated by the distance estimation unit is equal to or less than a predetermined threshold. The distance measurement apparatus according to claim 1 or 2, wherein telescopic image data is acquired. The wide-angle image acquisition unit acquires wide-angle image data captured by a wide-angle camera installed on the ship;
The ship detection unit detects image data of another ship from the wide-angle image data and calculates coordinates of the other ship in the wide-angle image data;
The approach determination unit compares the latest image data of the other ship detected by the ship detection unit with the past image data to determine whether the other ship is approaching or leaving the ship;
A step in which a telephoto image acquisition unit turns the telephoto camera installed on the own ship toward the other ship determined to be approaching by the approach determination unit, and acquires telephoto image data captured by the telephoto camera When,
A coordinate calculation unit calculating coordinates in the telephoto image data of the other ship determined to be approaching by the approach determination unit;
The triangulation unit uses the coordinates calculated by the ship detection unit and the coordinate calculation unit to triangulate the distance between the own ship and the other ship determined to be approaching by the approach determination unit. Calculating the distance according to

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