Radar image synthesis device, radar image synthesis method, and radar image synthesis program

Abstract

[Problem] To display a more highly visible synthesized image based on a plurality of radar images. [Solution] A radar image synthesis device equipped with: an acquisition unit for acquiring a plurality of radar images based on the measurement results from each of a plurality of radars which are positioned in different locations from one another; a generation unit for generating a synthesized image by synthesizing the plurality of radar images by setting, as the boundary between said radar images, the position at which a set of two or more radars yields the same product of radar beam width and distance from the radar; and a display processing unit for performing processing for displaying the synthesized image.

Description

[Technical Field]

[0001] The present invention relates to a radar image synthesis device, a radar image synthesis method, and a radar image synthesis program. [Background technology]

[0002] Conventionally, in order to eliminate blind spots in the field of view of radars mounted on ships, a technique has been known in which multiple radars are mounted at different positions on the ship and multiple radar images generated by each radar are synthesized and displayed. For example, Patent Document 1 (U.S. Patent No. 9,075,145) discloses a technique in which radar signals from two radars having different visibility angle ranges are combined and a single radar image based on the combined radar signals is displayed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,075,145 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional techniques, a composite image displayed based on multiple radar images may have low visibility. A technique that goes beyond such conventional techniques and is capable of displaying a composite image with higher visibility based on multiple radar images is desired.

[0005] The present invention has been made to solve the above-mentioned problems, and its object is to provide a radar image synthesis device, a radar image synthesis method, and a radar image synthesis program that are capable of displaying a composite image with higher visibility based on multiple radar images. [Means for solving the problem]

[0006] (1) In order to solve the above problem, a radar image synthesis device according to one aspect of the present invention includes an acquisition unit that acquires multiple radar images based on the measurement results of multiple radars arranged at different positions, a generation unit that generates a composite image in which the multiple radar images are synthesized, with the boundaries between the radar images being positions where the product of the radar beam width and the distance from the radar is equal for at least any two pairs of radars, and a display processing unit that performs processing to display the composite image.

[0007] In this way, by performing processing to display a composite image in which radar images are combined using the boundary between the radar images at a position where the product of the radar beam width and the distance from the radar is equal, even if a target appears across the boundary between radar images in the composite image, the size of the target appearing in one radar image will be equal to the size of the target appearing in the other radar image, making it possible to display a composite image in which the boundaries between radar images are not discontinuous, thereby making it possible to display a composite image with higher visibility based on multiple radar images.

[0008] (2) Preferably, the radar image synthesis device further includes a receiving unit that receives parameters indicating the position of each of the radars and the beam width of each of the radars.

[0009] With this configuration, it is possible to calculate appropriate positions as boundaries between radar images based on the received radar position and radar beam width, and generate a composite image.

[0010] (3) Preferably, the display processing unit performs processing to display the composite image further including the boundary line.

[0011] With this configuration, it is possible to display a composite image that is more convenient for the user and allows the boundaries between radar images to be recognized.

[0012] (4) Preferably, the display processing unit performs processing to display the composite image further including position information of each of the radars.

[0013] With this configuration, it is possible to display a composite image that is more convenient for the user and allows the user to recognize the position of each radar.

[0014] (5) Preferably, the plurality of radars are mounted on a ship.

[0015] With this configuration, it is possible to display a composite image with higher visibility, which is a composite of multiple radar images acquired on the ship.

[0016] (6) Preferably, the plurality of radars include the radar disposed on the bow side of the ship and the radar disposed on the stern side of the ship.

[0017] With this configuration, it is possible to display a composite image with higher visibility, in which the radar image of the bow side and the radar image of the stern side are combined.

[0018] (7) Preferably, the plurality of radars are the radar located on the bow side of the ship, the radar located on the stern side of the ship, the radar located on the port side of the ship, and the radar located on the starboard side of the ship.

[0019] With this configuration, it is possible to display a composite image with higher visibility, in which the radar image of the bow side, the radar image of the stern side, the radar image of the port side, and the radar image of the starboard side are combined.

[0020] (8) Preferably, the pairs of radars are a pair of the radar arranged on the bow side of the ship and a pair of the radar arranged on the port side of the ship, a pair of the radar arranged on the bow side of the ship and a pair of the radar arranged on the starboard side of the ship, a pair of the radar arranged on the stern side of the ship and a pair of the radar arranged on the port side of the ship, a pair of the radar arranged on the stern side of the ship and a pair of the radar arranged on the starboard side of the ship, and a pair of the radar arranged on the port side of the ship and a pair of the radar arranged on the starboard side of the ship.

[0021] With this configuration, it is possible to display a composite image in which four radar images of the area around the ship are efficiently combined.

[0022] (9) Preferably, the display processing unit performs processing to display the composite image with the position of the bridge of the ship as the center.

[0023] With this configuration, it is possible to display a composite image of a wider range in all directions, centered on the bridge of the ship.

[0024] (10) Furthermore, a radar image synthesis method according to a certain aspect of the present invention is a radar image synthesis method in a radar image synthesis device, which acquires a plurality of radar images showing the measurement results of a plurality of radars arranged at different positions, generates a composite image by synthesizing the plurality of radar images, with positions at which the product of the radar beam width and the distance from the radar is equal for at least any two pairs of radars as boundaries between the radar images, and performs processing to display the composite image.

[0025] In this way, by performing processing to display a composite image in which radar images are combined using the boundary between the radar images at a position where the product of the radar beam width and the distance from the radar is equal, even if a target appears across the boundary between radar images in the composite image, the size of the target appearing in one radar image will be equal to the size of the target appearing in the other radar image, making it possible to display a composite image in which the boundaries between radar images are not discontinuous, thereby making it possible to display a composite image with higher visibility based on multiple radar images.

[0026] (11) Furthermore, a radar image synthesis program according to a certain aspect of the present invention executes a process of acquiring a plurality of radar images based on measurement results of a plurality of radars arranged at different positions, a process of generating a composite image in which the plurality of radar images are synthesized, with a position where the product of the radar beam width and the distance from the radar is equal for at least any two pairs of the radars being the boundary between the radar images, and a process of displaying the composite image.

[0027] In this way, by performing processing to display a composite image in which radar images are combined using the boundary between the radar images at a position where the product of the radar beam width and the distance from the radar is equal, even if a target appears across the boundary between radar images in the composite image, the size of the target appearing in one radar image will be equal to the size of the target appearing in the other radar image, making it possible to display a composite image in which the boundaries between radar images are not discontinuous, thereby making it possible to display a composite image with higher visibility based on multiple radar images. [Effects of the Invention]

[0028] According to the present invention, it is possible to display a composite image with higher visibility based on a plurality of radar images. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram showing the configuration of a multi-radar system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of the mounting positions of the radars in the multi-radar system according to the embodiment of the present invention. [Figure 3] FIG. 3 is a diagram showing an example of a composite image generated by a radar image synthesis device according to a comparative example of the present invention. [Figure 4] FIG. 4 is a diagram illustrating a configuration of a radar image synthesis device according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating an example of a setting screen displayed on a display device in a multi-radar system according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram showing an example of a composite image generated by the radar image synthesis device according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing another example of a composite image generated by the radar image synthesis device according to the embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing the configuration of a multi-radar system according to a modified example of the embodiment of the present invention. [Figure 9] FIG. 9 is a diagram showing an example of the mounting positions of the radars in a multi-radar system according to a modified example of the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of a composite image generated by a radar image synthesis device according to a modified example of the embodiment of the present invention. [Figure 11] FIG. 11 is a flowchart defining an example of an operation procedure when the radar image synthesis device according to the embodiment of the present invention displays a synthesized image. [Figure 12] FIG. 12 is a flowchart defining an example of an operation procedure when the radar image synthesis device according to the embodiment of the present invention calculates a balanced position. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0031] [Configuration and basic operation] <Multi-radar system> Figure 1 is a diagram showing the configuration of a multi-radar system according to an embodiment of the present invention. Referring to Figure 1, the multi-radar system 301 includes multiple radars 20, a radar image synthesis device 101, and a display device 201. The multi-radar system 301 is mounted on a ship 1. Hereinafter, the width direction of the ship 1 is defined as the X direction, the length direction of the ship 1 is defined as the Y direction, and the vertical direction is defined as the Z direction.

[0032] For example, the multi-radar system 301 includes radars 20A and 20B arranged at different positions as the radar 20. The radar 20A is mounted on the bow side of the ship 1. The radar 20B is mounted on the stern side of the ship 1. The radar 20 is, for example, a millimeter-wave radar. The radar 20 may be an FM-CW (Frequency Modulated Continuous Wave) radar, a pulse radar, or another type of radar.

[0033] The radar 20 includes an antenna (not shown). The radar 20 measures the distance to a target S in a target area, which is an area surrounding the radar 20. The target area may be a circular area centered on the antenna, or a sector-shaped area that is a part of a circle centered on the antenna.

[0034] More specifically, the radar 20 transmits a transmission signal in the RF (Radio Frequency) band having a predetermined horizontal beam width to a divided target area, which is a part of the target area, via an antenna for each predetermined sweep period, and receives a reflected signal, which is a signal obtained by reflecting the transmission signal from a target S, via the antenna. The radar 20 rotates the antenna so that the azimuth angle of the transmission direction of the transmission signal shifts by a predetermined angle for each sweep period. For each sweep period, the radar 20 generates echo data indicating the measurement result of the distance to the target S in the divided target area based on the received reflected signal, and transmits the generated echo data to the radar image synthesis device 101.

[0035] FIG. 2 is a diagram showing an example of the mounting positions of the radars in the multi-radar system according to the embodiment of the present invention.

[0036] 2, the radars 20A and 20B are arranged along the Y direction. The radar-to-radar distance L, which is the distance between the radar 20A and the radar 20B in the Y direction, is, for example, several hundred meters.

[0037] For example, targets S1 and S2, which are targets S, exist between radar 20A and radar 20B. In the Y direction, the distance between radar 20A and target S1 is 1 / 3 of the inter-radar distance L, and the distance between radar 20B and target S1 is 2 / 3 of the inter-radar distance L. In addition, in the Y direction, the distance between radar 20A and target S2 and the distance between radar 20B and target S2 are 1 / 2 of the inter-radar distance L.

[0038] The radar 20A transmits a transmission signal Sa having a horizontal beam width θa via an antenna for each sweep period Wa, receives a reflected signal via the antenna, generates echo data, and transmits it to the radar image synthesis device 101.

[0039] The radar 20B transmits a transmission signal Tb having a horizontal beam width θb via an antenna for each sweep period Wb, receives a reflected signal via the antenna, generates echo data, and transmits it to the radar image synthesis device 101.

[0040] The sweep period Wa and the sweep period Wb may be periods of the same length or different lengths. The horizontal beam width θa and the horizontal beam width θb may be equal to or different from each other. The size of the target area of ​​the radar 20A and the size of the target area of ​​the radar 20B may be equal to or different from each other.

[0041] The radar image synthesis device 101 receives echo data from each radar 20 and generates a radar image for each radar 20 based on the received echo data. For example, the radar image is an image that shows the correspondence between XY coordinates and the echo intensity indicated by the echo data. The radar image synthesis device 101 generates a composite image by synthesizing the multiple radar images generated for each radar 20 and performs processing to display the generated composite image on the display device 201.

[0042] [assignment] However, in conventional techniques, a composite image generated by combining a plurality of radar images may have low visibility.

[0043] Fig. 3 is a diagram showing an example of a composite image generated by a radar image synthesis device according to a comparative example of the present invention. Fig. 3 shows a composite image XPc including an icon Ia indicating the mounting position of the radar 20A and an icon Ib indicating the mounting position of the radar 20B. In Fig. 3, the transmission signals Ta and Tb of the radars 20A and 20B are indicated by dashed lines, and a boundary line BLc, which is the boundary line between the radar images Pa and Pb, is indicated by a dashed-dotted line.

[0044] 3, the radar image synthesis device according to the comparative example generates a synthesized image XPc by synthesizing a radar image Pa based on echo data received from a radar 20A and a radar image Pb based on echo data received from a radar 20B. More specifically, the radar image Pa and the radar image Pb are each cropped, and the cropped radar image Pa and the cropped radar image Pb are synthesized to generate the synthesized image XPc.

[0045] Here, it is assumed that the horizontal beam widths θa and θb are equal to each other, and the target S1 is projected across the boundary line BLc in the composite image XPc. In this case, the distance between the radar 20A and the target S1 in the Y direction is shorter than the distance between the radar 20B and the target S1 in the Y direction, so the target S1 projected in the radar image Pa is smaller than the target S1 projected in the radar image Pb.

[0046] Therefore, the composite image XPc is a discontinuous image at the boundary between the radar image Pa and the radar image Pb, and has low visibility.

[0047] The multi-radar system 301 and radar image synthesis device 101 of the present disclosure solve the above problems by having the following configuration.

[0048] <Radar image synthesis device> 4 is a diagram illustrating a configuration of a radar image synthesis device according to an embodiment of the present disclosure. Referring to FIG. 4, the radar image synthesis device 101 includes a control unit 10, a receiving unit 14, and a storage unit 15. The control unit 10 includes an acquisition unit 11, a generation unit 12, and a display processing unit 13. The control unit 10 is, for example, a processing circuitry.

[0049] (Getting parameter information) The receiving unit 14 receives parameter information indicating the position of each radar 20 in the multi-radar system 301 and the beam width of each radar 20.

[0050] More specifically, the reception unit 14 receives an operation for performing initial setting by a user of the radar image synthesis device 101 when the radar 20 is installed on the ship 1. The reception unit 14 outputs operation information indicating the received operation to the display processing unit 13.

[0051] FIG. 5 is a diagram illustrating an example of a setting screen displayed on a display device in a multi-radar system according to an embodiment of the present disclosure.

[0052] 5, display processing unit 13 receives operation information from reception unit 14 and, in accordance with the received operation information, performs processing to display setting screen SC on display device 201. Setting screen SC includes text boxes TB1 to TB10.

[0053] The user of the radar image synthesis device 101 performs an operation to input parameter information such as the position of each radar 20 and the horizontal beam width of each radar 20 into the text boxes TB1 to TB10.

[0054] More specifically, the user performs an operation to input the hull length and width of the vessel 1 into text boxes TB1 and TB2, respectively. The user also performs an operation to input the X, Y, and Z coordinates of the mounting position of the radar 20A, with a predetermined position on the vessel 1 as the origin, into text boxes TB3 to TB5, respectively. The user also performs an operation to input the horizontal beam width θa of the radar 20A into text box TB6. The user also performs an operation to input the X, Y, and Z coordinates of the mounting position of the radar 20B, with a predetermined position on the vessel 1 as the origin, into text boxes TB7 to TB9, respectively. The user also performs an operation to input the horizontal beam width θb of the radar 20B into text box TB10. For example, the predetermined position of the vessel 1 is the center of the stern of the vessel 1.

[0055] The reception unit 14 stores the parameter information input by the user of the radar image synthesis device 101 into the text boxes TB1 to TB10 in the storage unit 15.

[0056] Note that instead of the user of the radar image synthesizer 101, the manufacturer of the radar image synthesizer 101 may perform the operation of inputting parameter information into the text boxes TB1 to TB10.

[0057] (radar image acquisition) Referring again to FIG. 4, the acquisition unit 11 acquires a plurality of radar images based on the measurement results of the plurality of radars 20 arranged at different positions.

[0058] More specifically, the acquisition unit 11 receives echo data from each radar 20 in the multi-radar system 301, associates the received echo data with the radar 20 that sent it, and stores the data in the storage unit 15. The acquisition unit 11 generates a plurality of radar images showing the measurement results of each of the plurality of radars 20 based on the echo data in the storage unit 15 at a generation timing according to a predetermined generation cycle.

[0059] For example, the acquisition unit 11 generates a radar image Pa indicating the position of the target S in the target area of ​​the radar 20A based on multiple pieces of echo data received from the radar 20A. The acquisition unit 11 also generates a radar image Pb indicating the position of the target S in the target area of ​​the radar 20B based on multiple pieces of echo data received from the radar 20B. The acquisition unit 11 stores the generated radar images Pa and Pb in the storage unit 15.

[0060] (Generating and displaying synthetic images) The generation unit 12 generates a composite image XP in which a plurality of radar images are combined, with a position where the product of the beam width of the radar 20 and the distance from the radar 20 is equal for at least any two pairs of radars 20 as the boundary between the radar images. In detail, the generation unit 12 uses the plurality of radar images Pa, Pb acquired by the acquisition unit 11 to generate a composite image XP in which the radar images Pa, Pb are combined, with a position where the product of the horizontal beam width of the radar 20 and the distance from the radar 20 is equal for the pair of radars 20A, 20B as the boundary between the radar images Pa, Pb.

[0061] More specifically, the generation unit 12 calculates a balanced position Cab, which is a position on the XY plane where the product Va of the horizontal beam width θa of the radar 20A and the distance from the radar 20A is equal to the product Vb of the horizontal beam width θb of the radar 20B and the distance from the radar 20B, based on the parameter information previously stored in the storage unit 15 by the reception unit 14. The generation unit 12 stores calculation information indicating the calculated balanced position Cab in the storage unit 15.

[0062] Each time the acquisition unit 11 saves radar images Pa, Pb in the memory unit 15, the generation unit 12 acquires the radar images Pa, Pb and calculation information from the memory unit 15, and generates a composite image XP by synthesizing the radar images Pa, Pb so that the equilibrium position Cab indicated by the calculation information becomes the boundary of the radar images Pa, Pb.

[0063] When the generation unit 12 generates the composite image XP, it outputs image information indicating the generated composite image XP to the display processing unit 13. Note that the generation unit 12 may perform signal processing such as echo averaging (EAV) and echo trail on the generated composite image XP, and output image information indicating the composite image XP after the signal processing to the display processing unit 13.

[0064] The display processing unit 13 performs processing to display the composite image XP generated by the generation unit 12.

[0065] The radar image composition device 101 may be configured to have a function of executing a user manual mode in which radar images are composed and displayed so that a composition position determined by the user corresponds to a boundary between radar images. More specifically, the reception unit 14 receives the composition position determined by the user and stores composition position information indicating the received composition position in the storage unit 15. When the user manual mode is on, the generation unit 12 generates a composite image XP by composing the radar images so that the composition position indicated by the composition position information in the storage unit 15 corresponds to a boundary between radar images.

[0066] (Example of composite image display 1) For example, the horizontal beam width θa and the horizontal beam width θb are equal to each other. In this case, the balanced position Cab calculated by the generation unit 12 indicates a straight line that passes through the midpoint of the line segment connecting the radar 20A and the radar 20B and is perpendicular to this line segment.

[0067] Fig. 6 is a diagram showing an example of a composite image generated by the radar image synthesis device according to the embodiment of the present invention. Fig. 6 shows a composite image XP1, which is an example of the composite image XP generated by the generation unit 12. In Fig. 6, the transmission signals Ta and Tb of the radars 20A and 20B are indicated by dashed lines, and a boundary line BL1, which is the boundary line between the radar images Pa and Pb in the composite image XP1, is indicated by a dashed-dotted line.

[0068] Referring to Figure 6, the generation unit 12 acquires the radar images Pa, Pb and the calculation information from the memory unit 15, and generates a composite image XP1 by combining the radar images Pa, Pb so that the balanced position Cab indicated by the calculation information becomes the boundary between the radar images Pa, Pb.

[0069] More specifically, the generation unit 12 removes, by trimming, a portion of the radar image Pa acquired from the storage unit 15 that is closer to the radar 20B than the balanced position Cab indicated by the calculation information. The generation unit 12 also removes, by trimming, a portion of the radar image Pb acquired from the storage unit 15 that is closer to the radar 20A than the balanced position Cab indicated by the calculation information. The generation unit 12 then generates a composite image XP1 by combining the trimmed radar images Pa and Pb.

[0070] For example, the generation unit 12 generates a composite image XP1 including an icon Ia indicating the mounting position of the radar 20A, an icon Ib indicating the mounting position of the radar 20B, an icon Iz indicating the position of the bridge of the ship 1, and a boundary line BL1. The icons Ia and Ib are examples of position information of the radars 20A and 20B.

[0071] Furthermore, for example, the generation unit 12 generates the composite image XP1 centered on the position of the bridge of the ship 1. The bridge of the ship 1 is, for example, a CCRP (Consistent Common Reference Point). Note that the generation unit 12 may generate the composite image XP1 centered on a position obtained by adding a predetermined offset according to the mounting position of each radar 20 to the position of the bridge of the ship 1.

[0072] The generation unit 12 outputs image information indicating the generated composite image XP1 to the display processing unit 13.

[0073] For example, the display processing unit 13 performs processing to display a composite image XP1 that includes the boundary line BL1 and the icons Ia and Ib and is centered on the position of the bridge of the ship 1. More specifically, the display processing unit 13 receives image information from the generation unit 12 and performs processing to display, on the display device 201, the composite image XP1 indicated by the received image information.

[0074] In this way, by generating the composite image XP1 by combining the radar images Pa and Pb so that the balance position Cab is the boundary between the radar images Pa and Pb, even if the target S2 is captured across the boundary line BL1, the size of the target S2 captured in the radar image Pa is the same as the size of the target S2 captured in the radar image Pb. Therefore, the composite image XP1 has high visibility because there are no discontinuous parts at the boundary between the radar images Pa and Pb.

[0075] (Example of composite image display 2) For example, the horizontal beam width θa is twice the horizontal beam width θb. In this case, the balanced position Cab indicates a straight line that passes through a point that divides the line segment connecting the radar 20A and the radar 20B internally at a ratio of 1:2 and is perpendicular to this line segment.

[0076] Fig. 7 is a diagram showing another example of a composite image generated by the radar image synthesis device according to the embodiment of the present invention. Fig. 7 shows a composite image XP2, which is an example of the composite image XP generated by the generation unit 12. In Fig. 7, the transmission signals Ta and Tb of the radars 20A and 20B are indicated by dashed lines, and a boundary line BL2, which is the boundary line between the radar images Pa and Pb in the composite image XP2, is indicated by a dashed-dotted line.

[0077] Referring to Figure 7, the generation unit 12 acquires the radar images Pa, Pb and the calculation information from the memory unit 15, and generates a composite image XP2 by combining the radar images Pa, Pb so that the balanced position Cab indicated by the calculation information becomes the boundary between the radar images Pa, Pb.

[0078] For example, the generation unit 12 generates a composite image XP2 including icons Ia, Ib, and Iz and a boundary line BL2. Furthermore, for example, the generation unit 12 generates a composite image XP2 centered on the position of the bridge of the ship 1. The generation unit 12 outputs image information indicating the generated composite image XP2 to the display processing unit 13.

[0079] The display processing unit 13 receives the image information from the generation unit 12 and performs processing to display on the display device 201 the composite image XP2 indicated by the received image information.

[0080] In this way, by generating the composite image XP2 by combining the radar images Pa and Pb so that the balance position Cab is the boundary between the radar images Pa and Pb, even if the target S1 is captured across the boundary line BL1, the size of the target S1 captured in the radar image Pa is the same as the size of the target S1 captured in the radar image Pb. Therefore, the composite image XP2 has high visibility because there are no discontinuous parts at the boundary between the radar images Pa and Pb.

[0081] In the radar image synthesis device 101 according to the embodiment of the present disclosure, the generation unit 12 is configured to calculate the balanced position Cab and generate the synthetic image XP by synthesizing the radar images Pa and Pb so that the calculated balanced position Cab is the boundary between the radar images Pa and Pb, but this is not limiting. The generation unit 12 may also be configured to generate the synthetic image XP without calculating the balanced position Cab.

[0082] For example, when the horizontal beam width θa and the horizontal beam width θb are equal, the generation unit 12 identifies, for each pixel of the composite image XP to be generated, the radar 20 that is closest to the XY coordinates corresponding to that pixel in the XY plane, extracts the pixel corresponding to the XY coordinates as a target pixel from the radar image of the identified radar 20, and generates a composite image XP configured from the extracted multiple target pixels. Note that, for pixels of the composite image XP to be generated that correspond to XY coordinates midway between the radars 20A and 20B, the generation unit 12 extracts the pixel corresponding to the XY coordinates from the radar image of one of the radars 20 as a target pixel.

[0083] <Modification> 8 is a diagram showing the configuration of a multi-radar system according to a modified embodiment of the present invention. Compared to multi-radar system 301, multi-radar system 302 further includes, as radars 20, radar 20C mounted on the port side of vessel 1 and radar 20D mounted on the starboard side of vessel 1.

[0084] The radar 20C transmits a transmission signal Tc having a horizontal beam width θc via an antenna for each sweep period Wc, receives a reflected signal via the antenna, generates echo data, and transmits it to the radar image synthesis device 101.

[0085] The radar 20D transmits a transmission signal Td having a horizontal beam width θd via an antenna for each sweep period Wd, receives a reflected signal via the antenna, generates echo data, and transmits it to the radar image synthesis device 101.

[0086] Some or all of the sweep periods Wa, Wb, Wc, and Wd may be periods of different lengths, or may all be periods of the same length. Also, for example, the horizontal beam widths θa, θb, θc, and θd are equal to one another.

[0087] The acquisition unit 11 in the radar image synthesis device 101 receives echo data from each radar 20 in the multi-radar system 302, and generates a radar image for each radar 20 that indicates the measurement results of that radar 20 based on the echo data.

[0088] More specifically, the acquisition unit 11 generates a radar image Pa indicating the position of the target S in the target area of ​​the radar 20A based on the multiple echo data received from the radar 20A. The acquisition unit 11 also generates a radar image Pb indicating the position of the target S in the target area of ​​the radar 20B based on the multiple echo data received from the radar 20B. The acquisition unit 11 also generates a radar image Pc indicating the position of the target S in the target area of ​​the radar 20C based on the multiple echo data received from the radar 20C. The acquisition unit 11 also generates a radar image Pd indicating the position of the target S in the target area of ​​the radar 20D based on the multiple echo data received from the radar 20D.

[0089] Based on the parameter information previously stored in the memory unit 15 by the receiving unit 14, the generating unit 12 calculates an equilibrium position, which is a position on the XY plane where the product of the horizontal beam width of one radar 20 of a pair of adjacent radars 20 and the distance from that radar 20 is equal to the product of the horizontal beam width of the other radar 20 and the distance from that other radar 20.

[0090] As an example, the generation unit 12 calculates multiple balanced positions by the following procedure: That is, the generation unit 12 selects a radar set consisting of any three radars 20 out of the four radars 20 in the multi-radar system 302, and calculates equidistant points, i.e., circumcenters, of the three radars 20 that make up the selected radar set.

[0091] Next, if the radar 20 closest to the circumcenter among the four radars 20 in the multi-radar system 302 is a radar 20 that does not constitute the radar set, the generating unit 12 discards the calculated circumcenter.

[0092] On the other hand, if the radars 20 closest to the circumcenter among the four radars 20 in the multi-radar system 302 are three radars 20 that make up a radar set, the generation unit 12 decides to use the circumcenter as a boundary point that is the boundary between three radar images based on the measurement results of the three radars 20, and stores the circumcenter.The generation unit 12 then calculates the equilibrium positions of the radars 20 for each of the three pairs of radars 20 in the three radars 20 that make up the radar set.

[0093] Next, the generation unit 12 repeats the selection of radar sets and the calculation of circumcenters until all combinations of radars 20 are selected as radar sets.

[0094] Specific examples of the plurality of balanced positions calculated by the generating unit 12 will be described below with reference to the drawings.

[0095] FIG. 9 is a diagram showing an example of the mounting positions of the radars in a multi-radar system according to a modified example of the embodiment of the present invention.

[0096] 9, the generation unit 12 calculates the circumcenter Eacd of the radars 20A, 20C, and 20D. Then, for the pair of radars 20A and 20C, the generation unit 12 calculates a balanced position Cac, which is a position on the XY plane where the product Va is equal to the product Vc of the horizontal beam width θc of the radar 20C and the distance from the radar 20C. Furthermore, for the pair of radars 20A and 20D, the generation unit 12 calculates a balanced position Cad, which is a position on the XY plane where the product Va is equal to the product Vd of the horizontal beam width θd of the radar 20D and the distance from the radar 20D. Furthermore, for the pair of radars 20C and 20D, the generation unit 12 calculates a balanced position Ccd, which is a position on the XY plane where the product Vc is equal to the product Vd.

[0097] The generation unit 12 also calculates the circumcenter Ebcd of the radars 20B, 20C, and 20D. The generation unit 12 then calculates a balanced position Cbc, which is a position on the XY plane where the product Vb is equal to the product Vc, for the pair of radars 20B and 20C. The generation unit 12 also calculates a balanced position Cbd, which is a position on the XY plane where the product Vb is equal to Vd, for the pair of radars 20B and 20D.

[0098] The balanced position Cac is a half line that is perpendicular to the line segment connecting the radar 20A and the radar 20C and extends from the circumcenter Eacd. The balanced position Cad is a half line that is perpendicular to the line segment connecting the radar 20A and the radar 20D and extends from the circumcenter Eacd. The balanced position Ccd is a half line that is perpendicular to the line segment connecting the radar 20C and the radar 20D and connects the circumcenter Eacd and the circumcenter Ebcd. The balanced position Cbc is a half line that is perpendicular to the line segment connecting the radar 20B and the radar 20C and extends from the circumcenter Ebcd. The balanced position Cbd is a half line that is perpendicular to the line segment connecting the radar 20B and the radar 20D and extends from the circumcenter Ebcd.

[0099] The generating unit 12 stores in the storage unit 15 calculation information indicating the calculated circumcenters Eacd, Ebcd and balanced positions Cac, Cad, Cbc, Cbd.

[0100] Each time the acquisition unit 11 saves radar images Pa, Pb, Pc, and Pd in ​​the memory unit 15, the generation unit 12 acquires the radar images Pa, Pb, Pc, and Pd and the calculation information from the memory unit 15, and generates a composite image XP by synthesizing the radar images Pa, Pb, Pc, and Pd so that the equilibrium positions Cac, Cad, Cbc, and Cbd indicated by the calculation information become the boundaries between the radar images Pa, Pb, Pc, and Pd.

[0101] After generating the composite image XP, the generation unit 12 outputs image information indicating the generated composite image XP to the display processing unit 13.

[0102] Fig. 10 is a diagram showing an example of a composite image generated by a radar image synthesis device according to a modified example of the embodiment of the present invention. Fig. 10 shows a composite image XP3, which is an example of a composite image XP generated by the generation unit 12. In Fig. 10, dashed dotted lines indicate a boundary line BL31 between radar images Pa and Pc, a boundary line BL32 between radar images Pa and Pd, a boundary line BL33 between radar images Pc and Pd, a boundary line BL34 between radar images Pb and Pc, and a boundary line BL35 between radar images Pb and Pd in ​​the composite image XP3.

[0103] Referring to Figure 10, the generation unit 12 generates a composite image XP3 by combining the radar images Pa, Pb, Pc, and Pd so that the balanced position Cac is the boundary between the radar images Pa and Pc, the balanced position Cad is the boundary between the radar images Pa and Pd, the balanced position Ccd is the boundary between the radar images Pc and Pd, the balanced position Cbc is the boundary between the radar images Pb and Pc, and the balanced position Cbd is the boundary between the radar images Pb and Pd.

[0104] For example, the generation unit 12 generates a composite image XP3 including an icon Ia indicating the mounting position of radar 20A, an icon Ib indicating the mounting position of radar 20B, an icon Ic indicating the mounting position of radar 20C, an icon Id indicating the mounting position of radar 20D, an icon Iz indicating the position of the bridge of the ship 1, an icon Iacd indicating the position of the circumcenter Eacd, an icon Ibcd indicating the position of the circumcenter Ebcd, and boundary lines BL31, BL32, BL33, BL34, and BL35. The generation unit 12 outputs image information indicating the generated composite image XP3 to the display processing unit 13.

[0105] The display processing unit 13 receives the image information from the generation unit 12 and performs processing to display on the display device 201 the composite image XP3 indicated by the received image information.

[0106] [Operation flow] Each device in the multi-radar system according to an embodiment of the present disclosure includes a computer including a memory, and a processing unit such as a CPU in the computer reads from the memory and executes a program including some or all of the steps in the following flowcharts and sequences. The programs for each of these devices can be installed externally. The programs for each of these devices are distributed in a state stored on a recording medium or via a communication line.

[0107] FIG. 11 is a flowchart defining an example of an operation procedure when the radar image synthesis device according to the embodiment of the present invention displays a synthesized image.

[0108] Referring to FIG. 11, first, the radar image synthesis device 101 receives echo data from the radar 20 in the multi-radar system 301, and stores the received echo data in the storage unit 15 (step S11).

[0109] Next, the radar image synthesis device 101 waits for the generation timing according to a predetermined generation cycle (NO in step S12), and repeatedly receives and stores echo data until the generation timing arrives (step S11). When the generation timing arrives (YES in step S12), the radar image synthesis device 101 acquires each echo data from the memory unit 15 and generates a radar image based on each acquired echo data (step S13).

[0110] Next, the radar image composition device 101 uses the generated multiple radar images to generate a composite image in which the radar images are composed so that the balance positions are boundaries between the radar images. More specifically, for example, the radar image composition device 101 acquires calculation information from the storage unit 15, and generates a composite image XP by combining the radar images so that the balance positions indicated by the calculation information are boundaries between the radar images (step S14).

[0111] Next, the radar image synthesis device 101 performs processing to display the generated synthesis image XP on the display device 201 (step S15).

[0112] Next, the radar image synthesis device 101 waits for a new generation timing (NO in step S12), and repeats receiving and storing echo data until the new generation timing arrives (step S11).

[0113] 12 is a flowchart showing an example of the operational procedure when the radar image synthesis device 101 calculates a plurality of balanced positions in the multi-radar system 302 according to the above-described modified example.

[0114] Referring to FIG. 12, first, the radar image synthesis device 101 receives parameter information indicating the position of each radar 20 in the multi-radar system 302 and the beam width of each radar 20 (step S21).

[0115] Next, the radar image synthesis device 101 selects a radar set consisting of any three radars 20 out of the four radars 20 in the multi-radar system 302 (step S22).

[0116] Next, the radar image synthesis device 101 calculates equidistant points, that is, circumcenters, of the three radars 20 that make up the selected radar set (step S23).

[0117] Next, the radar image synthesis device 101 determines whether the calculated circumcenter satisfies a predetermined condition. Specifically, the radar image synthesis device 101 determines whether the radar 20 closest to the circumcenter among the four radars 20 in the multi-radar system 302 satisfies a predetermined condition that the radar 20 is a radar 20 that constitutes a radar set (step S24).

[0118] Next, if the calculated circumcenter does not satisfy a predetermined condition (NO in step S25), the radar image synthesis device 101 discards the calculated circumcenter (step S26).

[0119] On the other hand, if the calculated circumcenter satisfies the predetermined condition, the radar image synthesis device 101 calculates the equilibrium positions of the radars 20 for each of the three pairs of radars 20 in the three radars 20 that make up the radar set (step S27).

[0120] Next, if there is an unselected combination of radars 20 as a radar set (YES in step S28), the radar image synthesis device 101 selects the radar set that is the unselected combination of radars 20 (step S22).

[0121] On the other hand, if there is no combination of radars 20 that has not been selected as a radar set (NO in step S28), the radar image synthesis device 101 stores the calculation information indicating the circumcenter and balanced position that have been calculated so far in the memory unit 15 (step S29).

[0122] In the radar image synthesis device 101 according to the embodiment of the present disclosure, the acquisition unit 11 is configured to receive echo data from the radar 20 in the multi-radar system 301 and generate a radar image based on the received echo data, but this is not limiting. The acquisition unit 11 may be configured to receive a radar image from the radar 20 instead of receiving echo data from the radar 20.

[0123] Furthermore, although the multi-radar system 302 according to the modified embodiment of the present disclosure is configured to include radars 20A, 20B, 20C, and 20D, this is not limitative. The multi-radar system 302 may be configured to include three or five or more radars 20.

[0124] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0125] 1 ship 11 Acquisition Department 12 Generation part 13 Display processing section 14 Reception Department 15 Storage section 20, 20A, 20B, 20C, 20D radar 101 Radar image synthesis device 201 Display device 301,302 Multi-radar System BL1,BL2,BL31~BL35,BLc boundary line Cac,Cad,Ccd,Cbc,Cbd Equilibrium position Eacd,Ebcd circumferential center Ia, Ib, Ic, Id, Iz, Iacd, Ibcd icons L radar distance Pa, Pb, Pc, Pd radar images S,S1,S2 Target SC setting screen Ta,Tb,Tc,Td Transmission signal TB1~TB10 text boxes XP1, XP2, XP3, XPc composite image θa, θb, θc, θd Horizontal beam width

Claims

1. an acquisition unit that acquires a plurality of radar images based on measurement results of a plurality of radars that are respectively arranged at different positions; a generating unit that generates a composite image by combining the plurality of radar images, with a position at which the product of the radar beam width and the distance from the radar is equal for at least any two of the radar pairs as a boundary between the radar images; and a display processing unit that performs processing to display the composite image.

2. The radar image synthesis device further comprises: The radar image synthesis device according to claim 1 , further comprising a reception unit that receives parameters indicating a position of each of the radars and a beam width of each of the radars.

3. 3. The radar image synthesis device according to claim 1, wherein the display processing unit performs processing to display the synthesized image further including the boundary line.

4. The radar image composition device according to claim 1 , wherein the display processing unit performs processing to display the composite image further including position information of each of the radars.

5. The radar image synthesis device according to claim 1 , wherein the plurality of radars are mounted on a ship.

6. 6. The radar image synthesis device according to claim 5, wherein the plurality of radars are the radar disposed on the bow side of the ship and the radar disposed on the stern side of the ship.

7. 6. The radar image synthesis device according to claim 5, wherein the plurality of radars are the radar arranged on the bow side of the ship, the radar arranged on the stern side of the ship, the radar arranged on the port side of the ship, and the radar arranged on the starboard side of the ship.

8. The set of radars The set of the radar arranged on the bow side of the vessel and the radar arranged on the port side of the vessel, The set of the radar arranged on the bow side of the vessel and the radar arranged on the starboard side of the vessel, The set of the radar arranged on the stern side of the vessel and the radar arranged on the port side of the vessel, The pair of the radar disposed on the stern side of the vessel and the radar disposed on the starboard side of the vessel; and 8. The radar image synthesis device according to claim 7, wherein the pair of radars is comprised of one radar disposed on the port side of the ship and the other radar disposed on the starboard side of the ship.

9. The radar image composition device according to claim 5 , wherein the display processing unit performs processing to display the composite image with the position of the bridge of the ship as the center.

10. A radar image synthesis method in a radar image synthesis device, comprising: acquiring a plurality of radar images showing respective measurement results of a plurality of radars disposed at different positions; generating a composite image in which the plurality of radar images are combined, with a position at which the product of the radar beam width and the distance from the radar is equal for at least any two of the radar pairs as a boundary between the radar images; A radar image synthesis method for performing processing to display the synthesized image.

11. A process of acquiring a plurality of radar images based on measurement results of a plurality of radars arranged at different positions; a process of generating a composite image by combining the plurality of radar images, with a position at which the product of the radar beam width and the distance from the radar is equal for at least any two of the radar pairs as a boundary between the radar images; and a radar image synthesis program for executing a process of displaying the synthesized image.

Images