JP6567237B2 - Distance measuring device and distance measuring method - Google Patents

Description

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

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

JP 2004-364212 A

  The object photographing apparatus according to Patent Document 1 is simply a method for calculating the distance from two cameras to the same object in the field of view, and is merely an application of triangulation. Since a certain amount of processing time is required to calculate the distance to the target by linking two cameras, if there are many other ships around the ship, the two cameras are linked for each other ship. It is not realistic to calculate the distance. Therefore, the conventional object photographing device has a problem that it 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. And

  A distance measuring apparatus according to the present invention includes a wide-angle image acquisition unit that acquires wide-angle image data captured by a wide-angle camera installed on the ship, and detects image data of another ship from the wide-angle image data and wide-angle image data. The ship detector that calculates the coordinates of other ships in the ship and the latest image data of the other ships detected by the ship detector and the past image data are compared to determine whether the other ship is approaching or leaving the ship. A telephoto image acquisition unit that rotates a telephoto camera installed on the own ship toward another ship determined to be approaching by the proximity determination unit and acquires telephoto image data captured by the telephoto camera; The coordinate calculation unit for calculating the coordinates in the telephoto image data of other ships determined to be approaching by the approach determination unit, and the coordinates calculated by the ship detection unit and the coordinate calculation unit There are, in which and a triangulation unit for calculating a distance between the other ships and ship it is determined in closer proximity decision unit in accordance with the principles of triangulation.

  According to the present invention, a wide-angle image data photographed by a wide-angle camera is used to detect another ship approaching the own ship, and the wide-angle image data and the telephoto image data photographed by the telephoto camera are used to detect from the own ship. Since the distance to the other ship is calculated, the distance to the other ship that may collide with the own ship can be measured using the image data of the wide-angle camera and the telephoto camera.

1 is a block diagram illustrating a configuration example of a distance measuring device according to Embodiment 1. FIG. 3 is a flowchart illustrating an operation example of the distance measuring apparatus according to the first embodiment. 6 is a diagram illustrating an example of wide-angle image data according to Embodiment 1. FIG. It is a figure which shows where the small area | region r1 in the wide-angle image data of the time t0 exists in the past wide-angle image data of the time t1-t3. 6 is a diagram illustrating an approach determination method by an approach determination unit according to Embodiment 1. FIG. 6 is a diagram illustrating turning control of a telephoto camera by a telephoto image acquisition unit according to Embodiment 1. FIG. It is a figure which shows the example of the wide-angle image data and telephoto image data which the wide-angle camera and the telephoto camera imaged in the situation of FIG. 7A, FIG. 7B, and FIG. 6 is a diagram illustrating a template matching method by a coordinate calculation unit according to Embodiment 1. FIG. 3 is a diagram illustrating a triangulation method by a triangulation unit according to Embodiment 1. FIG. It is a block diagram which shows the structural example of the distance measuring device which concerns on Embodiment 2. FIG. FIG. 11A and FIG. 11B are diagrams illustrating a hardware configuration example of the distance measuring device according to each embodiment.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram illustrating a configuration example of a distance measuring device 10 according to the first embodiment. The distance measuring device 10 is mounted on the own ship and 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. The The distance measuring 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 takes 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. In addition, when the angle of view of one wide-angle camera 20 cannot capture the entire periphery of the ship, the entire periphery of the ship may be imaged by a plurality of wide-angle cameras 20.
Hereinafter, the image data captured by the wide-angle camera 20 is referred to as “wide-angle image data”.

The telephoto camera 30 includes an actuator 31 that rotates the telephoto camera 30. The actuator 31 turns the telephoto camera 30 in accordance with the turning instruction from the telephoto image acquisition unit 14. The telephoto camera 30 is rotated by the actuator 31 and images the direction designated by the telephoto image acquisition unit 14 with the telephoto lens, and the image data is output to the telephoto image acquisition unit 14.
Hereinafter, the image data captured by the telephoto camera 30 is referred to as “telephoto image data”.

  The display 40 displays the distance between the ship and the other ship measured by the distance measuring device 10, the collision risk index of the ship and the other ship, and the like.

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

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

  FIG. 3 is a diagram illustrating an example of wide-angle image data in the first embodiment. FIG. 3 illustrates 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. Time goes back in order 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 oldest. In each wide-angle image data, it is confirmed that there is another ship near the center of the image and that this other ship is moving to the right side of the image. In addition, what is reflected on the left side of another ship is a breakwater.

  In step ST <b> 12, the ship detection unit 12 detects image data of another ship from the wide-angle image data and outputs it to the approach determination unit 13, calculates the coordinates of the other ship in the wide-angle image data, and outputs 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, examines where each small area is in the past wide-angle image data at times t1 to t3, and determines each small area. Other ships are detected based on the movements at times t1 to t3.
FIG. 4 is a diagram showing where the small region r1 in the wide-angle image data at time t0 is in the past wide-angle image data at times t1 to t3. Other ships have a feature of moving in an image in the same direction at a substantially constant speed in a short time. The ship detection unit 12 detects other ships using this feature. In FIG. 4, since the small area r1 is moving to the right side in the wide-angle image data at the times t1 to t3, the small area r1 is detected as another ship.

Note that where the small region r1 in the wide-angle image data at time t0 exists in the wide-angle image data at another time can be calculated by template matching. Since template matching is a well-known technique, detailed description is omitted.
Alternatively, the ship detection unit 12 may detect other ships based on machine learning using an artificial neural network or the like. A method for causing an artificial neural network to learn a specific object and discriminate whether or not to do so is described in Japanese Patent No. 6125137.

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

  For example, the approach determination unit 13 generates enlarged image data and reduced image data by enlarging and reducing the latest image data of the other vessel detected by the vessel detecting unit 12. 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 an approach determination method by the approach determination unit 13 according to the first embodiment. The approach determination unit 13 cuts out the image data of the other ship from the wide-angle image data at the time t0 based on the coordinates of the other ship detected by the ship detection unit 12, and sets it as the template image r10. Then, the approach determination unit 13 generates an image array including 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 a 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 a 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 is maximized. On the other hand, the approach determination unit 13 determines that the other ship is leaving 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 is maximized. . Note that the image data r11, r14, r16 reduced in the horizontal direction and the image data r13, r15, r18 expanded in the horizontal direction as the image array are required because another ship approaches or leaves the ship. This is to determine approach and departure when the horizontal length of the other ship changes due to a change in the direction of the other ship as viewed from the ship.

In addition, although the example in which the approach determination unit 13 uses the 3 × 3 image array is described in FIG. 5, it depends on the time difference between the past wide-angle image data and the latest wide-angle image data or the distance from the own ship to another ship. Image arrays with other numbers of images, such as 5 × 5, may be used. In addition, the approach determination part 13 uses the rough distance calculated by the distance rough calculation part 17 of Embodiment 2 mentioned later as a distance from the own ship to another ship, for example.
Further, the approach determination unit 13 may perform not only template matching between the image array and the wide-angle image data at the time t1, but also template matching with a plurality of past wide-angle image data. In that case, the approach determination unit 13 can obtain a correlation coefficient with higher certainty by statistically processing a plurality of template matching results.

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

  In step ST <b> 15, 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. Is output to the coordinate calculation unit 15.

  FIG. 6 is a diagram illustrating turning control of the telephoto camera 30 by the telephoto image acquisition unit 14 according to the first embodiment. 6 shows 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, and an approach determination unit. The telephoto camera 30 from the position cw of the wide-angle camera 20 when the base line is a virtual 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 base line up to the position cz is shown. The telephoto image acquisition unit 14 instructs the actuator 31 to turn so as to cause the telephoto camera 30 to image the other ship determined to be approaching by the approach determination unit 13, and the telephoto camera to face the same direction as the wide-angle camera 20. 30 direction is controlled.

  FIG. 7A is a diagram illustrating an example of wide-angle image data captured by the wide-angle camera 20 in the situation of FIG. FIG. 7B is a diagram illustrating 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 orientation of the telephoto camera 30 so that the orientations of the wide-angle camera 20 and the telephoto camera 30 are the same, and instructs the actuator 31 to turn. It is not a thing. For example, the telephoto image acquisition unit 14 sets the direction of the telephoto camera 30 so that the directions of the wide-angle camera 20 and the telephoto camera 30 are the same, and then makes sure 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. Further, for example, the telephoto image acquisition unit 14 sets the direction of the telephoto camera 30 based on the direction of the other ship 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 ST <b> 16, the coordinate calculation unit 15 calculates the coordinates in the telephoto image data of another 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 performed by the coordinate calculation unit 15 according to the first embodiment.
First, the coordinate calculation unit 15 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 enlargement ratio is determined by the ratio of the focal lengths of the wide-angle camera 20 and the telephoto camera 30. Image data obtained by enlarging image data of another ship in the wide-angle image data is referred to as “wide-angle ship image data”. Subsequently, the coordinate calculation unit 15 specifies the other ship in the telephoto image data B by performing template matching in the direction of the arrow with respect to the telephoto image data B using the wide-angle ship image data A as a template and coordinates. Calculate

  In step ST17, the triangulation unit 16 uses the coordinates calculated by the vessel detection unit 12 and the coordinate calculation unit 15 to triangulate the distance between the other vessel determined to be approaching by the approach determination unit 13 and the own vessel. Calculate according to the principle of surveying. And the triangulation part 16 outputs the information etc. which show the distance from own ship to another ship on the display 40, and displays them.

FIG. 9 is a diagram for explaining the triangulation method by the triangulation unit 16 according to 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 an angle α between the base line having the position cw of the wide-angle camera 20 as a vertex and the position s of the other ship. To do. Further, the triangulation unit 16 uses the coordinates of the other ship in the telephoto image data calculated by the coordinate calculation unit 15, and the angle β between the base line having the position cz of the telephoto camera 30 as the vertex and the position s of the other ship. Calculate Then, the triangulation unit 16 calculates the formula (1) to obtain the distance d from the base line to the position s of the other ship, that is, the distance d between the own ship and the other ship.

  As described above, the distance measuring apparatus 10 according to Embodiment 1 includes 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, 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 the coordinates of the other ship in the wide-angle image data. The approach determination unit 13 compares the latest image data of the other ship detected by the ship detection unit 12 and 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 in 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 the coordinates in the telephoto image data of the other ship determined to be approaching by the approach determination unit 13. The triangulation unit 16 uses the coordinates calculated by the vessel detection unit 12 and the coordinate calculation unit 15 to determine the distance between the other vessel determined to be approaching by the approach determination unit 13 and the own vessel based on the principle of triangulation. calculate. Thereby, the other ship which may collide with the own ship can be detected, and the distance between the detected other ship and the own ship can be measured using the image data of the wide-angle camera 20 and the telephoto camera 30. Therefore, even if a certain amount of processing time is required to measure the distance by linking the wide-angle camera 20 and the telephoto camera 30, the wide-angle camera 20 and the telephoto camera 30 are linked only to other ships approaching the ship. Since the distance d is measured, it is effective for avoiding a collision between another ship and the own ship.

  In addition, 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 enlarges the image data and the reduced image data. The correlation coefficient between the image data and the past image data of the other ship is calculated to determine the approach and departure of the other ship. Thereby, it is possible to accurately determine whether another ship is approaching or leaving the ship.

Embodiment 2. FIG.
FIG. 10 is a block diagram illustrating a configuration example of the distance measuring apparatus 10 according to the second embodiment. The distance measuring device 10 according to the second embodiment has a configuration in which a distance estimating unit 17 is added to the distance measuring device 10 according to the first embodiment shown in FIG. 10, parts that are the same as or correspond to those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  The distance approximating unit 17 estimates 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 formula (2) is obtained by the formula (3), the formula (4), and the formula (5).

Here, assuming that the ship is at coordinates (0, 0, 0) and is facing 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) is the coordinate of another ship in the wide-angle image data, (u0, v0) is the center coordinate in the wide-angle image data, c is the focal length of the wide-angle camera 20, and (ω, φ, κ) is the rolling angle of the wide-angle camera 20. Pitching angle and yawing angle are shown.

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. Get image data. Further, the triangulation unit 16 calculates the distance between the own ship and another ship. The threshold value 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, the telephoto image acquisition unit 14 receives the telephoto image data when the approach determination unit 13 determines that another ship is leaving or when the distance estimated by the distance estimation unit 17 is greater than a predetermined threshold. Do not get. Therefore, the triangulation unit 16 does not calculate the distance between the ship and the other ship. That is, when the other ship is leaving or when the other ship is far away, the possibility of the other ship colliding with the own ship is low, and thus the distance measurement by the distance measuring device 10 is unnecessary.

  As described above, the distance measuring device 10 according to the second embodiment includes the distance estimating unit 17 that 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. 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. Get image data. Thereby, the distance measuring device 10 can reduce the processing load without performing distance measurement of other ships that are unlikely to collide with the own ship. Even if it takes a certain amount of processing time to measure the distance by linking the wide-angle camera 20 and the telephoto camera 30, only the other ship that is close to the ship and that has an approximate distance d to the ship is close. Since the distance d is measured by linking the wide-angle camera 20 and the telephoto camera 30, it is further effective in avoiding a collision between another ship and the own ship.

Finally, a hardware configuration example of the distance measuring apparatus 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 measurement device 10 are realized by a processing circuit. Is done. That is, the distance measuring device 10 includes a processing circuit for realizing the above functions. The processing circuit may be the processing circuit 100 as dedicated hardware or the processor 102 that executes a program stored in the memory 101. The processing circuit 100 or the 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 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, or an ASIC (Application Specific Integrated Circuit). , 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. However, the functions of the respective units may be realized by a single 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 reads out and executes the program stored in the memory 101, thereby realizing the function of each unit. That is, the distance measuring device 10 includes a memory 101 for storing a program that, when executed by the processor 102, results in the steps shown in the flowchart of FIG. In addition, 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

Here, the processor 102 is a CPU (Central Processing Unit), a processing device, an arithmetic device, a microprocessor, a microcomputer, or the like.
The memory 101 may be a RAM (Random Access Memory), a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), or a nonvolatile or volatile semiconductor memory such as a flash memory, a hard disk, a flexible disk, or the like. The magnetic disk may be an optical disk such as a CD (Compact Disc) or a DVD (Digital Versatile Disc).

  Note that some 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 are partially dedicated hardware. It may be realized by a part, and a part may be realized by software or firmware. As described above, the processing circuit in the distance measuring apparatus 10 can realize the above-described functions by hardware, software, firmware, or a combination thereof.

  In the present invention, within the scope of the invention, any combination of each embodiment, any component of each embodiment can be modified, or any component of each embodiment can be omitted.

  Since the distance measuring device according to the present invention measures the distance to the other vessel approaching the own vessel, the distance measuring device is used for a distance measuring device that automatically detects other vessels having a possibility of collision. Is suitable.

  DESCRIPTION OF SYMBOLS 10 Distance measuring device, 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 estimation part, 20 Wide-angle camera, 20a, 30a 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 camera position, L Base length , R1 small area, r10 to r18 image data, s position of other ship, t0 to t3 time.

Claims (4)

A wide-angle image acquisition unit that acquires wide-angle image data captured by a wide-angle camera installed in 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 ship is approaching or leaving the own ship by comparing the latest image data and past image data of the other ship detected by the ship detection unit;
A telephoto image acquisition unit that rotates a telephoto camera installed in the ship to the other ship 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 and the own ship based on the principle of triangulation using the coordinates calculated by the ship detection unit and the coordinate calculation unit. And a distance measuring device.   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, the reduced image data, and the The distance measuring device according to claim 1, wherein a correlation coefficient with past image data of another ship is calculated to determine approaching and leaving of the other ship. A distance estimation unit that approximates the distance between the other vessel and the own vessel using the coordinates of the other vessel calculated by the vessel detection unit,
The telephoto image acquiring unit turns the telephoto camera when the approach determining unit determines that the other ship is approaching and the distance estimated by the distance estimating unit is equal to or less than a predetermined threshold. The distance measuring device according to claim 1, wherein telephoto image data is acquired. A wide-angle image acquisition unit acquiring wide-angle image data captured by a wide-angle camera installed on the ship;
A ship detecting unit detecting image data of another ship from the wide-angle image data and calculating coordinates of the other ship in the wide-angle image data;
An approach determining unit comparing the latest image data of the other ship detected by the ship detecting unit and past image data to determine whether the other ship is approaching or leaving the own ship;
A step of a telephoto image acquiring unit turning a telephoto camera installed on the own ship toward the other ship determined to be approaching by the approach determining unit, and acquiring telephoto image data captured by the telephoto camera; When,
A coordinate calculating unit calculating coordinates in the telephoto image data of the other ship determined to be approaching by the approach determining unit;
The triangulation section uses the coordinates calculated by the ship detection section and the coordinate calculation section to determine the distance between the other ship determined to be approaching by the approach determination section and the own ship, and the principle of triangulation A distance measurement method comprising the step of calculating according to

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