Measurement device and measurement method

Abstract

This measurement device comprises an acquisition unit, a storage unit, and a controller. The acquisition unit acquires a captured image from an imaging unit. The storage unit stores a virtual surface therein. The virtual surface is used for measuring the distance between an object on a road surface in space and the imaging unit. The controller generates a correction parameter on the basis of the difference between the altitude of a virtual surface at an arbitrarily defined location on a road surface and the altitude of the road surface in a real space. The controller corrects a virtual surface-based distance by using the correction parameter.

Description

Measuring device and measuring method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2022-054641, filed on March 29, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a measurement device and a measurement method.

[0003] It is known that a position in a camera coordinate system can be converted to a position on a road surface in real space based on the position and orientation of the surveillance camera in a space where the surveillance camera is installed. It is known that road plane parameters can be used to convert a position in the camera coordinate system to a position on the road surface in real space (see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2003-259357

[0005] A measuring device according to a first aspect includes: an acquisition unit that acquires an image of a space including a predetermined area from an imaging unit; a memory unit that stores a virtual surface used to measure the distance between an object on a road surface in the space and the imaging unit; and a controller that generates a correction parameter based on the difference between the elevation of the virtual surface at any point on the road surface and the elevation of the road surface in real space, and corrects the distance based on the virtual surface using the correction parameter.

[0006] A measurement method according to the second aspect includes storing a virtual surface to be used to measure the distance between an object on a road surface in a space imaged by an imaging unit and the imaging unit, obtaining an image of the space from the imaging unit, generating a correction parameter based on the difference between the elevation of the virtual surface at any point on the road surface and the elevation of the road surface in real space, and correcting the distance based on the virtual surface using the correction parameter.

[0007] FIG. 1 is a diagram showing an example of the configuration of a communication system including a measurement device according to an embodiment. FIG. 1 is a block diagram showing a schematic configuration of the measurement device of FIG. 1. FIG. 2 is a state diagram showing a fixed state of the measurement device of FIG. 1. FIG. 3 is a diagram explaining a method of setting a virtual surface based on the elevations of a plurality of calibration points. FIG. 4 is a diagram explaining a method of calculating the elevation of a calibration point based on a comparison between the position of the calibration point based on the image position and the position in real space. FIG. 5 is a diagram explaining a method of correcting a virtual surface. FIG. 6 is a diagram explaining an approximate straight line displayed on a correction image. FIG. 7 is a diagram showing an example of a correction image. FIG. 8 is a flowchart explaining calibration processing executed by the controller of FIG.

[0008] Hereinafter, an embodiment of a measuring device to which the present disclosure is applied will be described with reference to the drawings.

[0009] 1 shows an example of the configuration of a communication system 11 including a measurement device 10 according to an embodiment. The communication system 11 is, for example, a safe driving support communication system of an intelligent transport system (ITS). The safe driving support communication system is also called a safe driving support system or a safe driving support wireless system.

[0010] The measuring device 10 may be a device that observes a specific object of observation, such as a vehicle or a person on a road in a predetermined area. The measuring device 10 is, for example, a roadside device, a surveillance camera device, or the like. In this embodiment, the measuring device 10 is a roadside device that may be placed near an intersection where multiple roads 12 (roadways) intersect and observe the road surface. The measuring device 10 may also be placed on the side of the road other than at an intersection.

[0011] In the communication system 11, the measuring device 10 and a mobile object 13, such as a car traveling on a road 12, may communicate wirelessly with each other. Multiple mobile objects 13 may communicate wirelessly with each other. In the communication system 11, wireless communication may be performed including with an electronic device carried by a pedestrian 14. The electronic device is, for example, a mobile terminal device such as a smartphone.

[0012] The measuring device 10 may notify the mobile object 13 of support information for supporting the driver of the mobile object 13 in safe driving. The support information may include information about an observation target present on the road being observed. The information about the observation target may include whether or not the observation target is present, the type of the observation target present, and the distance to the measuring device 10. The measuring device 10 may notify the support information to an electronic device carried by the pedestrian 14.

[0013] The mobile object 13 may acquire various information notified from the measuring device 10 or the like using an electronic device mounted thereon. The electronic device mounted on the mobile object 13 may be, for example, a car navigation system. The electronic device mounted on the mobile object 13 may support the driver in safe driving by notifying the driver of warnings or other notifications based on the assistance information notified from the measuring device 10. Notifications to the driver may include the type and position of observed objects, such as other mobile objects 13, near the intersection where the driver is traveling, and the presence of pedestrians 14 on crosswalks 16 near the intersection.

[0014] As described above, the communication system 11 may assist the driver of the mobile object 13 in safe driving. The mobile object 13 is not limited to an automobile. For example, the mobile object 13 may include a motorcycle, a bus, a streetcar, or a bicycle.

[0015] The measuring device 10 will be described in detail below. The measuring device 10 measures the distance to an object on a road surface in a predetermined area. The object may be an object to be observed. The distance to the object may be the distance from an arbitrary origin in real space. The arbitrary origin is, for example, the road surface at the position of an imaging unit that provides an image to the measuring device 10, when viewing the three-dimensional real space from vertically above.

[0016] The measurement device 10 may have a measurement mode and a calibration mode as operation modes. In the measurement mode, the measurement device 10 may measure the distance to an object on the road surface. In the calibration mode, the measurement device 10 may set a virtual plane (described later) and generate correction parameters.

[0017] 2, the measurement device 10 includes an acquisition unit 17, a storage unit 18, and a controller 19. The measurement device 10 may further include a communication unit 20.

[0018] The acquisition unit 17 acquires captured images from the imaging unit. The imaging unit generates images by capturing an image of a space including the predetermined area. The imaging unit is, for example, a monocular camera. The monocular camera may be a visible light camera or an FIR camera. The imaging unit may generate captured images at a predetermined frame rate, such as 30 fps. Alternatively, the imaging unit may be, for example, a plurality of monocular cameras. In such a configuration, the plurality of monocular cameras may be the same type or different types.

[0019] A camera coordinate system may be defined for the imaging unit. The camera coordinate system may be a three-dimensional coordinate system with an origin at an arbitrary position in the imaging unit and three mutually perpendicular axes passing through the origin as coordinate axes. The origin of the camera coordinate system is, for example, the intersection of the detection axis of the imaging unit and the imaging element. The camera coordinate system may include, for example, the optical axis as one of its coordinate axes. The optical axis may pass through the center of the detection range of the imaging element. Furthermore, in a configuration in which the imaging unit is made up of multiple monocular cameras, a camera coordinate system may be defined for each monocular camera, or a camera coordinate system integrated across the multiple monocular cameras may be defined.

[0020] 3 , the imaging unit 21 may be fixed to a structure 22 having a height that allows it to capture an image of a scene including the road 12 outdoors, such as a traffic light, a utility pole, or a street light near an intersection where the road 12 intersects. The position and orientation of the imaging unit 21 relative to the structure 22 may be determined in advance. Furthermore, the position and orientation of the imaging unit 21 may be measured when the imaging unit 21 is actually installed and stored in the storage unit 18.

[0021] The position of the imaging unit 21 means the origin of the camera coordinate system relative to a reference position in a surrounding space coordinate system defined around the imaging unit 21. The orientation of the imaging unit 21 means the inclination of the coordinate axes of the camera coordinate system relative to the coordinate axes of the surrounding space coordinate system. The surrounding space coordinate system may have axes defined by the vertical direction of real space and two directions parallel to the horizontal plane and perpendicular to each other. Based on the position and orientation of the imaging unit 21, coordinates and trajectories of surfaces, lines, etc. in either the camera coordinate system or the surrounding space coordinate system can be converted into the other coordinate system.

[0022] The position and orientation of the imaging unit 21 may be determined so that the optical axis ox of the imaging unit 21 intersects with the surface of the road 12. The position and orientation of the imaging unit 21 may be determined so that the detection range of the imaging unit 21 includes a predetermined area defined for the measurement device 10.

[0023] 2 , the storage unit 18 includes any storage device, such as a RAM (Random Access Memory) or a ROM (Read Only Memory), etc. The storage unit 18 may store various programs that cause the controller 19 to function and various information that the controller 19 uses.

[0024] The storage unit 18 stores a virtual plane. The virtual plane is used to measure the distance between the imaging unit 21 and an object on the road surface in the space captured in the captured image ci. The virtual plane is, for example, a plane set in a surrounding space coordinate system. The virtual plane may be an entire plane, or may be a plurality of planes that are curved and continuous.

[0025] 3, since any position in the captured image ci corresponds to a tilt direction with respect to the optical axis ox, any image position ap in the captured image ci can be made to correspond to a first line sl1 in the camera coordinate system. The intersection of the first line sl1 and the virtual plane can be detected as the position of an object on the road surface, and the distance between the object on the road surface and the image capture unit 21 can be measured based on the detected position and the position of the image capture unit 21.

[0026] The storage unit 18 may further store at least one of correction parameters and correction planes, which will be described later.

[0027] The communication unit 20 may be controlled by the controller 19 to perform wireless communication with the mobile object 13. The communication unit 20 may be configured with a communication circuit and an antenna. The antenna may be, for example, an omnidirectional antenna. The communication unit 20 may perform wireless communication using, for example, the 700 MHz band allocated to ITS. The communication unit 20 may also perform wireless communication using, for example, a wireless LAN (Local Area Network).

[0028] The communication unit 20 may perform various processes such as amplification on the signal received by the antenna, and output the processed received signal to the controller 19. The communication unit 20 may perform various processes such as amplification on the information acquired from the controller 19, and wirelessly transmit the processed transmission signal from the antenna.

[0029] The controller 19 includes one or more processors and memories. The processor may include a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific integrated circuit (ASIC). The processor may include a programmable logic device (PLD). The PLD may include a field-programmable gate array (FPGA). The controller 19 may be either a system-on-a-chip (SoC) or a system in a package (SiP), in which one or more processors work together.

[0030] In the measurement mode, the controller 19 may determine whether or not an object to be observed exists in a predetermined area based on an image acquired from the imaging unit 21. Specifically, the controller 19 may detect a subject image corresponding to the subject to be observed by known image recognition such as pattern matching or deep learning for the image. The controller 19 may determine whether or not the object to be observed exists by detecting the subject image.

[0031] In the measurement mode, when an observation target is present, the controller 19 may identify the type of the observation target based on the observation results of the imaging unit 21. Specifically, the controller 19 may identify the type of the observation target by detecting the subject image and performing image recognition.

[0032] In the measurement mode, if an object to be observed exists, the controller 19 may acquire the distance to the position where the object to be observed exists based on the image. The distance is acquired by, for example, calculation by the controller 19.

[0033] In the measurement mode, the controller 19 may specifically identify an image position in a two-dimensional coordinate system of the imaging pixels of a portion of the detected image of the subject to be observed that is in contact with the road surface. The controller 19 may identify a first straight line sl1 corresponding to the identified image position. The controller 19 may identify an intersection of the first straight line sl1 with a virtual plane as the position where the object to be observed is located. The controller 19 may recognize the distance from the imaging unit 21 to the intersection as the distance based on the virtual plane. The controller 19 may calculate the distance between the object and the imaging unit 21 by directly or indirectly correcting the distance based on the virtual plane using a correction parameter described below.

[0034] For example, the controller 19 may directly correct the distance based on the virtual surface by correcting a portion of the virtual surface near the intersection of the first straight line sl1 and the virtual surface using correction parameters and determining the intersection of the corrected portion with the first straight line sl1. Correction of the virtual surface using correction parameters will be described later. Alternatively, for example, the controller 19 may indirectly correct the distance based on the virtual surface by determining the intersection of the first straight line sl and a correction plane that is set by correcting the virtual surface using the correction parameters in the calibration mode, as described later.

[0035] In the measurement mode, when at least one observation target is present, the controller 19 may generate assistance information including the type and distance of the observation target. The controller 19 may control the communication unit 20 to notify the generated assistance information to the mobile objects 13 around the measurement device 10.

[0036] In the calibration mode, the controller 19 may set a reference horizontal plane. The reference horizontal plane may be a horizontal plane at the height of the intersection between a line extending vertically downward and passing through the position of the imaging unit 21 and the road surface. The reference horizontal plane may be set based on a predetermined position of the imaging unit 21 or a position of the imaging unit 21 measured at the time of installation. The controller 19 may acquire the measured position of the imaging unit 21 from an input device connected via the acquisition unit 17 or the communication unit 20, and may store the measured position of the imaging unit 21 in the memory unit 18.

[0037] In the calibration mode, the controller 19 may set a virtual surface. To set the virtual surface, any position on the road surface in real space may be set as a calibration point. A target may be placed at the calibration point. An image of the target may be captured by the imaging unit 21. The position of the calibration point in real space relative to the imaging unit 21 may be measured. The actual measurement of the position may be performed by an operator using an instrument. Alternatively, the actual measurement of the position may be performed by a positioning device such as a Global Navigation Satellite System (GNSS) provided on the target.

[0038] In the calibration mode, the controller 19 may detect the image position of the target in the captured image ci of the target, in other words, the image position of the calibration point. The controller 19 may set a straight line corresponding to the image position. The controller 19 may detect an intersection of the straight line with a reference horizontal plane, thereby detecting an estimated position in real space of the calibration point based on the image position.

[0039] In the calibration mode, the controller 19 may acquire the position of the calibration point in real space. The position in real space may be acquired as a position in a surrounding space coordinate system. The controller 19 may acquire the position from the acquisition unit 17 or an input device connected via the communication unit 20, and may store the position in the storage unit 18. Alternatively, the controller 19 may acquire the position from a positioning device connected via the communication unit 20, and may store the position in the storage unit 18.

[0040] In the calibration mode, the controller 19 may set a virtual plane based on the image positions of the calibration points in the captured images ci and their positions in real space. To set the virtual plane, the controller 19 may calculate the elevation of the calibration points based on the image positions in the captured images ci and their positions relative to the imaging unit 21 in real space. The elevation may be the height from a reference horizontal plane in the vertical direction. The controller 19 may calculate the elevation for a plurality of different calibration points. As shown in FIG. 4 , the controller 19 may set an approximate straight line as based on the elevations h of a plurality of different calibration points cp as the virtual plane.

[0041] A method for calculating the elevation h of the calibration point cp will be described below. The controller 19 compares the estimated position of the calibration point cp in real space, which is detected based on the image position of the calibration point cp, with its position relative to the imaging unit 21 in real space. Through this comparison, the controller 19 calculates the elevation h of the calibration point cp relative to the reference horizontal plane rh in real space. For example, as shown in FIG. 5 , the controller 19 calculates, as the elevation h, the height from the reference horizontal plane rh of the intersection between a second straight line sl2 extending from the imaging unit 21 toward a position p1 based on the captured image ci and a line extending vertically through a position p2 (actually measured position) relative to the imaging unit 21 in real space.

[0042] More specifically, when position p1 based on the captured image is farther from the origin o than position p2 relative to the imaging unit 21 in real space, the altitude h is calculated using equation (1) based on the ratio of similar triangles. The origin o is the intersection of a line extending vertically downward through the position of the imaging unit 21 and the reference horizontal plane rh.

[0043] h = {(OP1 - OP2) / OP1} × H (1) where OP1 is the distance from the origin o to a position p1 based on the captured image ci, OP2 is the distance from the origin o to a position p2 relative to the imaging unit 21 in real space, and H is the height of the position of the imaging unit 21 from the reference horizontal plane rh.

[0044] Furthermore, when the position p2 relative to the imaging unit 21 in real space is farther from the origin o than the position p1 based on the captured image ci, the altitude h is calculated by equation (2) using the ratio of similar triangles.

[0045] h={(OP1-OP2) / OP1}×H (2)

[0046] The controller 19 may set a virtual plane without using the elevation h of the calibration point cp. For example, the controller 19 may set a reference horizontal plane rh as the virtual plane.

[0047] In the calibration mode, the controller 19 may generate a correction parameter based on the difference between the elevation of a virtual surface at an arbitrary point on the road surface and the elevation of the road surface in real space. The correction parameter may be any parameter that modifies at least a portion of the virtual surface to a corrected surface. The corrected surface is a virtual surface in which a portion of the virtual surface is made closer to the elevation of the road surface in real space. The controller 19 may acquire the elevation of the arbitrary point on the road surface and the elevation of the real space from an input device connected via the acquisition unit 17 or the communication unit 20, and may store the acquired information in the memory unit 18.

[0048] For example, as shown in FIG. 6 , when acquiring the elevation H1 in real space at an arbitrary point sp on the road surface, the controller 19 corrects the virtual surface represented as an approximate straight line as so that the correction plane cs passes through the road surface in real space at the arbitrary point sp. In correcting the approximate straight line as, the controller 19 may also correct the portion near the arbitrary point sp. The controller 19 may correct the portion near the arbitrary point sp to a curved line. Alternatively, the controller 19 may correct the portion near the arbitrary point sp to a straight line. The controller 19 may maintain the shape of the approximate straight line as for the portion other than the vicinity of the arbitrary point sp. The controller 19 may generate correction parameters for correcting the virtual surface as described above based on the difference between the elevation of the virtual surface at the arbitrary point sp and the elevation H1 of the road surface in real space.

[0049] In the calibration mode, the controller 19 may generate a correction image for inputting an arbitrary point on the road surface and an elevation H1 in real space. The correction image is an image of an approximated line as at an arbitrary position in a direction that intersects a plane parallel to the optical axis direction of the imaging unit 21 and the vertical direction in real space and is parallel to a horizontal plane in real space, viewed from that direction. As shown in FIG. 7 , the approximated line as at an arbitrary position in a direction intersecting the plane fs1 is the intersection between a plane fs2 perpendicular to the direction intersecting the plane fs1 and a virtual plane at an arbitrary position in the direction intersecting the plane fs1. Therefore, the correction image is an image showing the approximated line as on the plane fs2.

[0050] As shown in FIG. 8 , in the correction image, an arbitrary position in a direction perpendicular to the vertical direction can be specified to specify the elevation, in other words, the position of the road surface in the vertical direction. A specific example is described below. The controller 19 may display the correction image on a display connected via the acquisition unit 17 or the communication unit 20. An operator checking the display may input the elevation at an arbitrary position in the vertical direction into an input device. The input device may be a touch panel provided on the display displaying the correction image. The controller 19 may acquire the elevation at an arbitrary position in the vertical direction from the input device via the acquisition unit 17 or the communication unit 20 as an elevation H1 in real space for correcting the approximate line as. In a configuration in which the input device is a touch panel, an arbitrary position in the vertical direction and the elevation at that position may be detected by pressing an arbitrary position in the correction image with a pointer pen or the like.

[0051] In the correction image, the position where the controller 19 acquires the altitude for correcting the virtual surface may be determined arbitrarily by the operator, but the position of the calibration point cp may be used together with the altitude h.

[0052] In the calibration mode, at least a portion of the virtual surface may be corrected along a straight line parallel to a lane in the space captured by the image capture unit 21. The lane may include a traffic lane and a sidewalk. Therefore, any point for generating the correction parameters may be set on a straight line parallel to the lane in the space. Furthermore, a direction intersecting a plane fs1 parallel to the optical axis direction of the image capture unit 21 and the vertical direction in the real space may be determined so that the correction image is parallel to the lane.

[0053] In the calibration mode, the virtual surface may be corrected for each of a plurality of lanes in the space captured by the imaging unit 21. Therefore, any point for generating correction parameters may be set for each of a plurality of lanes. Also, correction parameters may be generated for each of a plurality of lanes. Also, the above-mentioned correction image may be generated for each of a plurality of lanes so as to be parallel to the corresponding lanes.

[0054] In the calibration mode, in a configuration in which correction parameters are generated for each of a plurality of lanes, virtual surfaces may also be set for each of a plurality of lanes.

[0055] Next, the calibration process executed by the controller 19 in this embodiment will be described with reference to the flowchart in Fig. 9. The calibration process is started by switching the operation mode to the calibration mode using an input device after the measurement device 10 is installed. In the calibration mode, a display and an input device are connected to the measurement device 10.

[0056] In step S100, the controller 19 issues a request to input the position of the calibration point cp to the display. After the request is issued, the process proceeds to step S101.

[0057] In step S101, the controller 19 determines whether or not an imaging command requesting imaging of the target at the calibration point cp has been received via the input device. If not, the process returns to step S101. If yes, the process proceeds to step S102.

[0058] In step S102, the controller 19 acquires the captured image ci from the imaging unit 21. In a configuration in which the imaging unit 21 is driven under the control of the controller 19, the controller 19 acquires the captured image ci by issuing an imaging command. In a configuration in which the imaging unit 21 generates the captured image ci without the control of the controller 19, the controller 19 acquires the captured image ci of the frame immediately after acquiring the imaging command in step S101. After acquisition, the process proceeds to step S102.

[0059] In step S103, the controller 19 calculates the altitude h of the target at the calibration point cp based on the position of the calibration point cp relative to the imaging unit 21, whose input was requested in step S100, and the position of the target in the captured image ci acquired in step S102. After calculating the altitude h, the process proceeds to step S104.

[0060] In step S104, the controller 19 displays a message asking whether or not a calibration point should be added to the display. After adding the calibration point, the process proceeds to step S105.

[0061] In step S105, the controller 19 determines whether it has received an input indicating that a calibration point cp has been added or that no calibration point cp has been added. If it has received an input indicating that a calibration point cp has been added, the process returns to step S101. If it has received an input indicating that no calibration point cp has been added, the process proceeds to step S106.

[0062] In step S106, the controller 19 sets a virtual surface based on the altitude h calculated in step S103. After setting, the process proceeds to step S107.

[0063] In step S107, the controller 19 generates a correction image including an approximate straight line as corresponding to the virtual surface set in step S106. Furthermore, the controller 19 applies the correction image to the display and causes it to be displayed. After generation, the process proceeds to step S108.

[0064] In step S108, the controller 19 determines whether or not the altitude H1 of an arbitrary position perpendicular to the vertical direction in the correction image has been acquired. If it has been acquired, the process proceeds to step S109. If it has not been acquired, the process proceeds to step S110.

[0065] In step S109, the controller 19 generates correction parameters based on the altitude on the virtual surface set in step S106 and the altitude H1 whose acquisition was confirmed in step S108. Furthermore, the controller 19 corrects the virtual surface based on the correction parameters. Furthermore, the controller 19 stores the corrected virtual surface in the storage unit 18. After the correction, the process proceeds to step S110.

[0066] In step S110, the controller 19 determines whether or not it has received an input to end the calibration mode. If not, the process returns to step S107. If yes, the calibration process ends.

[0067] The measuring device 10 of this embodiment configured as described above includes a memory unit 18 that stores a virtual plane used to measure the distance between an object on a road surface in space and the image capture unit 21, and a controller 19 that generates a correction parameter based on the difference between the elevation of the virtual plane at an arbitrary point on the road surface and the elevation H1 of the road surface in real space, and corrects the distance based on the virtual plane using the correction parameter. With this configuration, the measuring device 10 corrects the distance based on the virtual plane using the image position of the object image on the road surface to account for the unevenness of the actual road surface relative to the virtual plane. Therefore, the measuring device 10 can improve the accuracy of distance measurements using images.

[0068] Furthermore, the measuring device 10 of this embodiment indirectly corrects the distance using a correction plane cs, which is a virtual plane corrected using correction parameters. With this configuration, the measuring device 10 generates the correction plane cs in advance and corrects the distance based on the correction plane cs during measurement. This can reduce the time required for correcting the distance after acquiring the captured image ci compared to a configuration in which the distance is directly corrected using correction parameters each time a measurement is made.

[0069] Furthermore, in the measuring device 10 of this embodiment, the virtual plane is set based on the image position in the captured image ci of the calibration point cp at an arbitrary position on the road surface and the position in real space relative to the imaging unit 21. With this configuration, the measuring device 10 sets the virtual plane used for measuring distance based on the position of the calibration point cp in real space, which can further improve the accuracy of distance measurement using an image compared to a configuration in which an arbitrary plane is set as the virtual plane.

[0070] Furthermore, the measuring device 10 of this embodiment generates a correction image of an approximate line as at any position in a direction parallel to a horizontal plane in real space that intersects with a plane fs1 parallel to the optical axis direction of the imaging unit 21 and the vertical direction in real space, and views the approximate line as from that direction. The elevation at any position on the approximate line as in the correction image is acquired as the elevation H1 in real space. With this configuration, the measuring device 10 allows the operator performing calibration to visually recognize the shape of the virtual surface. Therefore, by having the operator compare the shape of the road surface in real space with the shape of the virtual surface, the measuring device 10 can visually reflect the elevation H1 in real space on the virtual surface. Therefore, the measuring device 10 allows the operator to easily correct the virtual surface.

[0071] In addition, in the measuring device 10 of this embodiment, any point for generating the correction parameters is set on a line parallel to the lanes within the space, and is set for each of multiple lanes within the space, and correction parameters are generated for each of the multiple lanes. Correcting the elevation at multiple points on the road surface increases the processing load on the controller 19. In response to such an event, the measuring device 10 having the above-described configuration corrects the elevation at positions along the lanes, thereby preventing an excessive increase in processing load and enabling distance measurement with the required measurement accuracy.

[0072] The above has described an embodiment of the measuring device 10, but embodiments of the present disclosure can also be embodied as a method or program for implementing the device, as well as a storage medium on which a program is recorded (for example, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a hard disk, or a memory card, etc.).

[0073] Furthermore, the implementation form of the program is not limited to application programs such as object code compiled by a compiler or program code executed by an interpreter, but may also be in the form of a program module incorporated into an operating system. Furthermore, the program may or may not be configured so that all processing is performed solely by the CPU on the control board. The program may also be configured so that part or all of it is executed by another processing unit mounted on an expansion board or expansion unit added to the board as needed.

[0074] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0075] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art could make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined or divided into one.

[0076] For example, in this embodiment, the measuring device 10 is configured as a device separate from the imaging unit 21 , but the measuring device 10 may be configured to include the imaging unit 21 .

[0077] All of the features described in this disclosure and / or all steps of all of the disclosed methods or processes may be combined in any combination except combinations in which these features are mutually exclusive. Furthermore, each feature described in this disclosure may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless expressly denied. Thus, unless expressly denied, each disclosed feature is only one example of a generic series of identical or equivalent features.

[0078] Furthermore, embodiments of the present disclosure are not limited to the specific configurations of any of the above-described embodiments, but rather extend to any novel feature or combination thereof described herein, or any novel method or process step or combination thereof described herein.

[0079] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, the configurations distinguished by descriptions such as "first" and "second" can have their numbers exchanged. For example, the first line can exchange the identifiers "first" and "second" with the second line. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the identifier exchange. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number.

[0080] REFERENCE SIGNS LIST 10 Measuring device 11 Communication system 12 Road 13 Mobile object 14 Pedestrian 15 Traffic light 16 Crosswalk 17 Acquisition unit 18 Memory unit 19 Controller 20 Communication unit 21 Imaging unit 22 Structure ap Arbitrary image position as Approximation line ci Captured image cp Calibration point cs Correction plane ox Optical axis p1 Position based on captured image p2 Position in real space rh Reference horizontal plane sl1 First line sl2 Second line sp Arbitrary point

Claims

1. an acquisition unit that acquires an image of a space including a predetermined area from an imaging unit; a storage unit that stores a virtual plane used to measure a distance between an object on a road surface in the space and the imaging unit; a controller that generates a correction parameter based on a difference between an elevation of the virtual surface at an arbitrary point on the road surface and an elevation of the road surface in a real space, and corrects the distance based on the virtual surface using the correction parameter. Measuring equipment.

2. 2. The measuring device according to claim 1, The controller indirectly corrects the distance by using a correction plane obtained by correcting the virtual plane using the correction parameters. Measuring equipment.

3. 3. The measuring device according to claim 1, The virtual surface is set based on an image position in the captured image and a position in real space of a calibration point at an arbitrary position on the road surface. Measuring equipment.

4. 4. The measuring device according to claim 3, An elevation of the calibration point is calculated based on the image position at the calibration point and the position of the calibration point relative to the imaging unit, and an approximation straight line based on the elevations of a plurality of different calibration points is set as the virtual surface. Measuring equipment.

5. 5. The measuring device according to claim 4, The controller: generating an image of the approximate straight line at an arbitrary position in a direction that intersects with a plane parallel to the optical axis direction of the imaging unit and the vertical direction in real space and is parallel to a horizontal plane in the real space, as viewed from the direction; The altitude at any point in the image is acquired as the altitude in the real space. Measuring equipment.

6. 3. The measuring device according to claim 1, An arbitrary point for generating the correction parameter is set on a straight line parallel to the lane in the space. Measuring Equipment

7. 7. The measuring device according to claim 6, The arbitrary points for generating the correction parameters are set for each of a plurality of lanes in the space; The correction parameters are generated for each of the plurality of lanes. Measuring equipment.

8. 8. The measuring device according to claim 7, The virtual surface is set for each of the plurality of lanes. Measuring equipment.

9. storing a virtual plane used to measure a distance between an object on a road surface in a space captured by the imaging unit and the imaging unit; Acquiring a captured image of the space from the imaging unit; generating a correction parameter based on a difference between an elevation of a virtual surface at an arbitrary point on the road surface and an elevation of the road surface in a real space; The distance based on the virtual surface is corrected by the correction parameter. Measurement method.