Imaging system

Abstract

This imaging system is installed on a mobile body, and captures an image of an object that is distant from the mobile body in motion and that is at least part of the surroundings of the mobile body. The imaging system comprises: an imaging device that captures a plurality of images at consecutive image capture timings; a distance measurement device that acquires distance information on the distance to an object for which the imaging device captures an image next on a distance measurement axis that does not pass through an optical element of the imaging device; and a control device that controls the imaging device on the basis of the distance information. The distance measurement device is installed frontward of the imaging device in the traveling direction of the mobile body, with a predetermined distance therebetween.

Description

Imaging system

[0001] The present disclosure relates to an imaging system that is fixed to a moving body and captures images while the moving body is moving.

[0002] As transportation infrastructure ages, there is a growing demand for infrastructure inspections. Instead of visual inspections by humans, inspection efficiency can be dramatically improved by capturing images of infrastructure facilities using moving vehicles and then detecting defects through image processing.

[0003] For example, in Patent Document 1, a camera installed in a vehicle captures an image of a target area while the vehicle is moving. Furthermore, camera movement can cause blurring when the vehicle is traveling at high speed. Patent Document 1 addresses this by using saccade mirror technology to correct motion blur. Light is irradiated onto the target, and the light reflected by the target is reflected by a mirror that rotates for a predetermined exposure time and then incident on the camera, thereby reducing blurring.

[0004] International Publication No. 2023 / 002826

[0005] However, when capturing images while moving, if the distance to the object to be captured is measured before capturing the image, the timing for capturing the image will come while the distance is being measured, so the faster the moving speed, the more difficult it is to capture the image based on the measured distance.

[0006] The present disclosure provides an imaging system that improves imaging accuracy by using distance information to an imaging target while moving.

[0007] The imaging system disclosed herein is installed on a moving body and captures an image of an imaging target that is at least a part of the surroundings of the moving body at a distance from the moving body. The imaging system includes an imaging device that captures multiple images at successive imaging timings, a ranging device that acquires distance information to the imaging target that the imaging device is to next image using a ranging axis that does not pass through the optical element of the imaging device, and a control device that controls the imaging device based on the distance information. The ranging device is installed a predetermined distance away from the imaging device in the direction of travel of the moving body.

[0008] According to the imaging system of the present disclosure, it is possible to provide an imaging system that improves imaging accuracy by using distance information to an imaging target while moving.

[0009] FIG. 1 is a side view illustrating a vehicle equipped with an imaging system according to a first embodiment; FIG. 2 is a front view illustrating a vehicle equipped with an imaging system according to a first embodiment; FIG. 3 is a block diagram illustrating the internal configuration of an imaging system according to a first embodiment; FIG. 4 is an explanatory diagram illustrating an imaging area of ​​an imaging device and a ranging point of a ranging device according to a first embodiment; FIG. 5 is a flow chart illustrating imaging processing according to a first embodiment;

[0010] (Embodiment 1) Hereinafter, embodiment 1 will be described with reference to the drawings. In embodiment 1, an example will be described in which the moving body is a vehicle 3 such as an automobile, and the imaging system 1 is attached to the top of the vehicle 3. As an example, the imaging system 1 of embodiment 1 is disposed to capture an image of a wall 5 erected beside a road. The wall 5 is, for example, a soundproof wall or a tunnel wall. Note that in each drawing, the positive direction of the X axis is the forward direction of the vehicle 3, the Z axis direction is the up-down direction, and the Y axis direction is the direction perpendicular to the XZ plane.

[0011] [1-1. Configuration of the Imaging System] Please refer to FIGS. 1 to 3. FIGS. 1 and 2 are diagrams for explaining the imaging system 1. Note that the distance measuring device 13 is omitted from FIG. 2 to make the optical axis 23a easier to see. FIG. 3 is a block diagram showing the internal configuration of the imaging system 1. In FIGS. 1 and 2, a vehicle 3 is traveling on, for example, a road 4. A wall 5 erected on the side of the road 4 has, for example, a hole 5b and a crack 5c. These holes 5b and cracks 5c can be detected from the captured image by image processing.

[0012] The imaging target of the imaging system 1 is at least a part of a structure surrounding the vehicle 3, and is an object that moves relatively in accordance with the moving speed of the vehicle 3 as the vehicle 3 moves. The imaging area 9 is an imaging area of ​​this imaging target that is acquired as a single image. Note that in addition to the wall 5, the imaging target may also be a road, the side or bottom of an overpass, a utility pole, or a power line. This makes it possible to detect holes, cracks, lifting, peeling, joints, tilting of a utility pole, and bending of a power line in the imaging target by image processing from the acquired image.

[0013] The imaging system 1 is installed on the top surface of a vehicle 3. The imaging system 1 is fixed so as to capture an image of a wall 5 on the side of the vehicle 3 in Fig. 1. The imaging system 1 may also be installed on the bed of a truck or the like.

[0014] The imaging system 1 includes an imaging device 11, a distance measuring device 13, and a control device 15. The imaging device 11 captures an image of the surroundings of the vehicle 3, and in the first embodiment, captures an image of the wall surface 5a of the wall 5. The imaging device 11 includes a lens barrel 21, a lens 23, a shutter 24, an imaging element 25, a camera control unit 27, and a focus mechanism 28.

[0015] Lens barrel 21 has lens 23 attached thereto, and houses shutter 24, image sensor 25, camera control unit 27, and focus mechanism 28. Within lens barrel 21, image sensor 25 is disposed at a position corresponding to focal length F of lens 23.

[0016] The lens 23 is disposed so that its optical axis faces directly toward the wall 5, which is the subject. The lens 23 may be attached to the lens barrel 21 in an exchangeable manner. The lens 23 is composed of one or more lenses.

[0017] The image sensor 25 converts the received light into an electrical signal according to its intensity, and is, for example, a solid-state image sensor such as a CCD image sensor, a CMOS image sensor, or an infrared image sensor.

[0018] The lens 23 includes a focus lens 29, which is a lens for changing the focus state of the image pickup target formed on the image pickup element 25 in the optical system of the imaging device 11. The focus lens 29 is composed of one or more lenses. Note that the lens 23 may not include the focus lens 29, and a focus module may be attached separately from the lens 23.

[0019] The focus motor 30 drives the focus lens 29 to move forward and backward along the optical axis 23a of the optical system of the imaging device 11 under the control of the focus command unit 32. This makes it possible to change the focus state of the subject image formed on the image sensor 25 in the optical system. In the first embodiment, a stepping motor is used as the focus motor 30. However, the focus motor 30 is not limited to this and may be configured as a DC motor or an ultrasonic motor, for example.

[0020] The camera control unit 27 opens the shutter 24 for a predetermined time while receiving an exposure instruction signal from the control device 15, or after receiving an exposure instruction signal from the control device 15. The shutter 24 may be configured with a plurality of aperture blades that open and close, or may be an electronic shutter.

[0021] The distance measuring device 13 measures the distance to the imaging target and acquires distance information Df. The distance measuring device 13 transmits the acquired distance information Df to the control device 15. The distance measuring device 13 is, for example, a laser rangefinder. The distance measuring device 13 is disposed a predetermined distance away from the imaging device 11 in the traveling direction of the vehicle 3. In the first embodiment, for example, the optical axis 23a of the lens 23 of the imaging device 11 and the distance measuring axis 13a of the distance measuring device 13 are separated by a predetermined distance Dv. Therefore, the distance measuring axis 13a of the distance measuring device 13 does not pass through the optical elements of the imaging device 11 and is an axis different from the optical axis 23a of the optical system.

[0022] The control device 15 is a circuit that can be realized using semiconductor elements or the like. The control device 15 can be configured with, for example, a microcomputer, a CPU, an MPU, a GPU, a DSP, an FPGA, or an ASIC. The functions of the control device 15 may be configured with hardware alone, or may be realized by combining hardware and software. The control device 15 realizes predetermined functions by reading data and programs stored in the storage unit 17 and performing various arithmetic processing.

[0023] The control device 15 transmits an exposure control signal to the camera control unit 27. The exposure control signal has two types of signals: a high signal serving as an ON signal instructing exposure, and a low signal serving as an OFF signal that does not instruct exposure. When capturing images at a constant frame rate, the camera control unit 27 may control the exposure instead of the control device 15.

[0024] Control device 15 has a subject distance calculation unit 31 and a focus command unit 32. Subject distance calculation unit 31 calculates the subject distance to the imaging target based on distance information received from distance measurement device 13. The calculated subject distance is sent from subject distance calculation unit 31 to focus command unit 32.

[0025] Calculation of the subject distance Lg will be described with reference to Figure 4. The subject distance Lg is the distance from the principal point of the lens 23, which is disposed between the subject and the image sensor 25, to the subject. The imaging device 11 is disposed so that the optical axis 23a of its optical system is oriented in a direction perpendicular to the traveling direction of the vehicle 3. The distance measuring device 13 is installed so that the distance measuring axis 13a is tilted at a predetermined angle θa toward the direction perpendicular to the traveling direction of the vehicle 3.

[0026] The subject distance calculation unit 31 of the control device 15 calculates the subject distance Lg from the imaging device 11 to the imaging area 9 of the wall 5 that is the imaging target, based on the distance information Df acquired by the distance measuring device 13 .

[0027] The subject distance calculation unit 31 calculates the subject distance Lg, for example, based on the distance information Df and the predetermined angle θa, using the following formula: Lg = Df × |cos(θa-90)| + Lα (1) Here, the constant Lα is an offset value for converting the distance from the distance measuring device 13 into the distance from the image capturing device 11. The constant Lα is, for example, the amount of deviation between the distance measuring device 13 and the image capturing device 11 along the Y-axis direction. In the first embodiment, for example, the predetermined angle θa is 90 degrees. Note that the subject distance calculation unit 31 may acquire the subject distance by referring to a conversion table between distance information and subject distance stored in the storage unit 17.

[0028] The focus command unit 32 acquires the position of the focus lens 29 based on the received subject distance Lg, and calculates the drive amount of the focus motor 30 corresponding to the acquired position of the focus lens 29. A table showing the relationship between the subject distance Lg and the position of the focus lens 29 is stored in the storage unit 17, and the focus command unit 32 acquires the position of the focus lens 29 corresponding to the subject distance Lg by referring to the table. The focus command unit 32 controls the focus of the lens 23 by controlling the drive of the focus motor 30 based on the calculated drive amount. Note that instead of using the table, the subject distance Lg may be calculated using a function that converts the subject distance Lg into the position of the focus lens 29.

[0029] The imaging system 1 also includes a storage unit 17 and an operation unit 19. The storage unit 17 is a storage medium that stores programs and data required to realize the functions of the control device 15. The storage unit 17 can be realized by, for example, a hard disk drive (HDD), an SSD, a RAM, a DRAM, a ferroelectric memory, a flash memory, a magnetic disk, or a combination of these.

[0030] The operation unit 19 is an input device through which the user gives instructions to the control device 15. The operation unit 19 may be an input device dedicated to the imaging system 1 or may be a mobile terminal such as a smartphone. When a mobile terminal is used as the operation unit 19, the operation unit 19 and the control device 15 transmit and receive data via wireless communication. Using the operation unit 19, the user may instruct the control device 15 whether the imaging area is a dark indoor area such as a tunnel or a bright outdoor area such as a mountain slope or road, or may instruct the imaging interval Tf. The imaging interval Tf is the time between the end of imaging of the current image and the end of imaging of the next image. In the case of video imaging, it is the time for one frame, and in the case of still image imaging, it is the time interval between imaging times of images to be captured. In the case of video imaging, the frame rate (the number of images captured per second) may also be specified.

[0031] [1-2. Operation of the Imaging System] Next, the operation of the imaging system 1 will be described with reference to FIGS. 5 to 9. FIG. 5 is a flowchart showing the imaging process performed by the imaging system 1. FIG. 6 is a graph showing the relationship between exposure time and the timing of acquiring distance information. FIG. 6(a) is a graph showing the timing of the exposure time for each frame. The imaging interval Tf is exemplified as imaging intervals Tf1 and Tf2 for each frame, and the exposure time Tp is exemplified as exposure times Tp1, Tp2, and Tp3 for each frame. The exposure times Tp1, Tp2, and Tp3 are the times from imaging start times t1, t3, and t5 to imaging end times t2, t4, and t6, respectively. FIG. 6(b) is a graph showing the timing of distance measurement. FIG. 7 is an explanatory diagram showing the imaging of the nth image, FIG. 8 is an explanatory diagram showing the movement process for capturing the nth to n+1th images, and FIG. 9 is an explanatory diagram showing the imaging of the n+1th image.

[0032] 5 is started, for example, when an instruction to start imaging is given from the operation unit 19 while the vehicle 3 is moving. In addition, by the user setting the section of road to be imaged from the operation unit 19, the control device 15 can determine, for example, based on GPS information and travel distance, whether the vehicle has traveled on the set section of road.

[0033] The imaging period for the imaging target may be set at a predetermined period, or the user may set the imaging period using the operation unit 19. Exposure may be synchronized with a vehicle speed pulse signal. The control device 15 may perform imaging upon detecting that the vehicle 3 is moving, in addition to receiving an instruction from the user via the operation unit 19 to start imaging.

[0034] In step S1, the distance measuring device 13 measures distance information Dfn1 to the imaging area 9n+1 of the wall 5 in the image In+1 of the frame following the nth frame image In captured by the imaging device 11. The distance information Dfn1 measured by the distance measuring device 13 may be distance information for only one point within the imaging area 9n+1, or distance information Dfn1 for multiple points along the traveling direction of the vehicle 3 relative to the imaging area 9n+1.

[0035] 6 and 7, the distance measuring device 13 continuously measures the distance information Dfn1 to the imaging area 9n+1. In the example shown in FIG. 6B, the distance measuring device 13 continuously acquires the distance information Df at a predetermined sampling frequency in accordance with a distance measurement instruction from the subject distance calculation unit 31. The subject distance calculation unit 31 acquires a predetermined number of samples of distance information Df before and after the exposure timing of the image of the current frame, and performs focus driving of the image of the next frame. Note that the subject distance calculation unit 31 may change the number of samples to be acquired depending on the traveling speed of the vehicle 3, or may estimate the timing of the next imaging from the traveling speed of the vehicle 3 and acquire a predetermined number of samples of distance information Df before the next imaging.

[0036] Alternatively, the distance measuring device 13 may constantly measure, and the subject distance calculation unit 31 may acquire the distance information Df for the image of the next or subsequent frame only while the image of the current frame is being exposed. This allows the distance information Df to be acquired (extracted) in synchronization with the exposure control signal, making it easier to acquire the distance information from multiple distance information that is constantly measured.

[0037] Alternatively, distance measuring device 13 may measure distance information Df for images of subsequent frames only during exposure of the image of the current frame, and subject distance calculation unit 31 may acquire only the measured distance information Df during exposure. For example, distance information Dfn1 for image In+1 may be measured only during exposure time Tp1 from time t1 to time t2 when imaging device 11 captures image In for imaging area 9n.

[0038] Alternatively, the subject distance calculation unit 31 may instruct the distance measuring device 13 to acquire distance information for at least one point along the direction of travel in the imaging region 9n+1, for example, distance information Dfn1 for three points in this case, and use the acquired distance information Dfn1 for the three points. Note that although measurement of the distance information Dfn1 continues after time t2, the measurement of the distance measuring device 13 for the imaging region 9n+1 may be terminated before the optical axis 23a of the imaging device 11 enters the imaging region 9n+1, as shown in FIG.

[0039] In step S2, the subject distance calculation unit 31 calculates the subject distance Lgn1 to the image capture area 9n+1 based on the acquired distance information Dfn1. When the distance information Dfn1 is measured at multiple points in the image capture area 9n+1, the subject distance calculation unit 31 calculates the subject distance Lgn1 based on the multiple pieces of distance information Dfn1 along the traveling direction of the vehicle 3.

[0040] In this case, the subject distance calculation unit 31 may calculate a median Dfn1m of the multiple pieces of distance information Dfn1 and calculate the subject distance Lgn1 based on the median Dfn1m of the distance information. Alternatively, the subject distance calculation unit 31 may calculate the subject distance Lgn1 based on distance information obtained by excluding, from the multiple pieces of distance information Dfn1, distance information that differs by a predetermined amount from the average value Dfn1v. For example, the subject distance Lgn1 may be calculated using any one piece of distance information Dfn1 from the multiple pieces of distance information Dfn1 obtained by excluding distance information that differs by a predetermined amount from the average value Dfn1v. Alternatively, the subject distance calculation unit 31 may filter the multiple pieces of distance information Dfn1 using a low-pass filter to remove singular points from the multiple pieces of distance information Dfn1.

[0041] Alternatively, an average value Dfn1v of multiple pieces of distance information Dfn1 may be calculated, and the subject distance Lgn1 may be calculated based on the average value Dfn1v of the distance information. The subject distance calculation unit 31 may also calculate the subject distance Lgn1 based on an average value Dfn1v2 of the distance information Dfn1, which is obtained by excluding distance information that differs by a predetermined amount from the average value Dfn1v.

[0042] In step S3, the focus command unit 32 acquires the position of the focus lens 29 based on the received subject distance Lg using a table or a conversion function stored in the storage unit 17. In step S4, the focus command unit 32 calculates the drive amount of the focus motor 30 corresponding to the acquired position of the focus lens 29, and adjusts the focus of the lens 23 by driving and controlling the focus motor 30 based on this drive amount.

[0043] In step S4, the focus command unit 32 may compare the subject distance Lg with a first threshold value to determine whether to operate the focus mechanism 28. For example, the focus command unit 32 may determine not to perform a focus operation if the detected subject distance Lg is equal to or greater than the first threshold value. The first threshold value is a predetermined value. Since the pixel resolution (e.g., [mm / pixel]) of the image sensor 25 decreases as the subject distance Lg increases, the required pixel resolution cannot be obtained when the subject distance Lg exceeds a certain distance. In this case, focusing is not very effective, and the operation to focus on a long distance may result in a delay in the focus operation when switching from a close distance to a medium distance. Furthermore, because a subject distance greater than expected may not be the desired subject, the responsiveness of the focus operation can be maintained by preventing a focus operation from being wasted.

[0044] The focus command unit 32 may also compare the difference between the subject distance Lg of the current frame and the subject distance Lg of the next frame with a predetermined threshold to determine whether to operate the focus mechanism 28. For example, the absolute value of the change in the subject distance Lg of the (n+1)th image In+1 relative to the subject distance Lg of the nth image In may be compared with a threshold, and it may determine not to operate the focus mechanism 28 if the absolute value of the change in the subject distance Lg is equal to or greater than the threshold. If the subject distance Lg changes by more than a certain distance between frames, the focus cannot track, and the focus mechanism 28 is not operated. Furthermore, if the subject distance Lg changes by more than a certain distance between frames, it is possible that the subject is not the desired subject. Therefore, by not performing unnecessary focus operations, the responsiveness of the focus operation can be maintained.

[0045] The focus command unit 32 may also compare the absolute value of the change in the subject distance Lg of the (n+1)th image In+1 relative to the subject distance Lg of the nth image In with a second threshold value to adjust the amount of operation of the focus mechanism. The second threshold value may be a table of focus positions (command values ​​to the focus motor 30) corresponding to the subject distance Lg, or a value calculated using a function that correlates the subject distance Lg with the focus position.

[0046] In step S5, the vehicle 3 travels and captures an image of the imaging area 9n+1 as the imaging target of the imaging device 11. For example, the control device 15 continues to send a Hi signal to the camera control unit 27 of the imaging device 11 for the exposure time Tp2. This causes the imaging element 25 to capture an image of the imaging area 9n+1 for the exposure time Tp2. The image In+1 captured by the imaging element 25 is recorded from the camera control unit 27 to the storage unit 17. At this time, the focus of the imaging device 11 has already been appropriately adjusted, so that a high-precision image In+1 can be acquired.

[0047] In step S6, the control device 15 determines whether or not imaging of the imaging targets for all set track sections has been completed. If the control device 15 determines that imaging of the imaging targets for all set track sections has been completed (Yes in step S6), the imaging process while moving ends. If the control device 15 determines that imaging of the imaging targets for all set track sections has not been completed (No in step S6), the process is repeated again from step S1. In step S1, the distance measuring device 13 measures distance information Dfn1 to imaging area 9n+2 of wall 5 in image In+2 of the frame following image In+1 of the n+1th frame captured by the imaging device 11.

[0048] In step S2, the subject distance calculation unit 31 may calculate the subject distance Lgn1 based on the distance information Dfn and Dfn1 of the imaging target from which the nth and n+1th images In and In+1 are acquired. For example, the average value of the distance information Dfn and Dfn1 is calculated, and the subject distance Lgn1 is calculated based on this average value. Subsequently, the imaging device 11 repeats the processes of steps S3 to S6, capturing multiple images In, In+1, and In+2 at consecutive imaging timings. As shown in FIGS. 7 to 9 , in these captured images, the image captured in the current frame and the image captured in the immediately preceding frame partially overlap in their imaging areas. Images In and In+1 share a common imaging area, and images In+1 and In+2 share a common imaging area. In this way, the imaging device 11 captures images at consecutive imaging timings, thereby capturing consecutive images along the direction of movement of the vehicle 3.

[0049] [1-3. Effects, etc.] As described above, the imaging system 1 is installed on a vehicle 3 and captures an image of an imaging target that is at least a part of the surroundings of the moving vehicle 3 at a distance from the vehicle 3. The imaging system 1 includes an imaging device 11 that captures multiple images In, In+1, and In+2 at successive imaging timings, a ranging device 13 that acquires distance information to the next imaging target that the imaging device 11 is scheduled to capture using a ranging axis 13a that does not pass through the lens 23 of the imaging device 11, and a control device 15 that controls the imaging device 11 based on the distance information Dfn and Dfn1. The ranging device 13 is installed a predetermined distance Dv away from the imaging device 11 in the direction of travel of the vehicle 3.

[0050] Since the vehicle 3 captures multiple images In, In+1, and In+2 at consecutive imaging timings while traveling, the subject distance Lg changes for each image. Even in this case, the subject distance Lg is detected with sufficient time before capturing images, making it possible to obtain clear images through control based on distance information. In this way, an imaging system 1 is realized that improves imaging accuracy by using information about the distance to the imaging target while moving.

[0051] The imaging device 11 also has a focus mechanism that focuses on the imaging target, and the distance measuring device 13 acquires distance information to the first imaging target (imaging area 9n+1), which is the imaging target of the first image (image In+1), before the imaging device 11 captures the first image (image In+1). The control device 15 controls the focus mechanism 28 when capturing the first image based on the distance information. Even if the subject distance Lg changes for each image, the subject distance Lg is detected before capturing, ensuring responsiveness of the focus control. This allows the lens 23 to be focused even with a small aperture value, making it possible to capture clear images with high-precision focus control even in dark environments such as the wall of a tunnel.

[0052] Furthermore, the distance measuring device 13 acquires distance information Dfn1 for at least one point in the first imaging target area (9n+1) before the optical axis 23a of the imaging device 11 moves into the first imaging target area (9n+1) due to the movement of the vehicle 3. This makes it possible to more reliably ensure time for focus control before the imaging device 11 starts imaging the first imaging target area.

[0053] The predetermined distance Dv will be described with reference to Fig. 9. If the distance traveled by the vehicle 3 between two consecutive images is Lp, the imaging range of the imaging device in the direction of movement of the vehicle 3 is Ax, and the predetermined distance between the imaging device 11 and the distance measuring device 13 is Dv, the predetermined distance Dv satisfies the following equation: Dv ≧ Lp - Ax / 2 (2).

[0054] When the predetermined distance Dv satisfies the condition of equation (2), distance information for at least one point in the next imaging area can be obtained at the time of completion of exposure for the current imaging, and the maximum time can be secured for focus control for the next imaging.

[0055] Furthermore, the predetermined distance Dv may further satisfy the condition of the following equation (3) in addition to the condition of equation (2): Lp+Ax / 2≧Dv (3).

[0056] When the specified distance Dv satisfies the condition of equation (3), distance information will not be acquired beyond the next imaging area at the time the exposure for the current image is completed, that is, distance measurement within the next imaging area will not be performed too early, thereby suppressing detection distance errors due to changes in vehicle attitude after distance measurement.

[0057] 10 , the distance measuring device 13 may be installed with the distance measuring axis 13a tilted at a predetermined angle θb toward the traveling direction of the vehicle 3 with respect to the optical axis 23a of the imaging device 11. The control device 15 calculates the subject distance Lg based on the distance information Df acquired by the distance measuring device 13 and the predetermined angle θb.

[0058] Furthermore, as a modification of the first embodiment, the subject distance calculation unit 31 may calculate the subject distance Lg, for example, based on the distance information Df and the predetermined angle θb, using the following formula: Lg=Df×cos(θb)+Lα (4) Here, the constant Lα is an offset value for converting the distance from the distance measuring device 13 into the distance from the image capturing device 11. The constant Lα is, for example, the amount of deviation between the distance measuring device 13 and the image capturing device 11 along the Y-axis direction. Even if the subject distance Lg is calculated in this manner, it is possible to achieve the acquisition of a clear image through highly accurate focus control, as described above.

[0059] (Embodiment 2) Next, an imaging system 1A according to embodiment 2 will be described with reference to Figs. 11 to 13. Fig. 11 is a block diagram showing the internal configuration of the imaging system 1A according to embodiment 2. Fig. 12A is a perspective view showing the appearance of the imaging device 11A. Fig. 13 is an explanatory diagram illustrating motion blur correction in the imaging system 1A.

[0060] The imaging system 1A in the second embodiment is configured by adding a blur correction mechanism 40 to the imaging system 1 in the first embodiment. Except for this point and points described below, the imaging system 1A in the second embodiment is the same as the imaging system 1 in the first embodiment.

[0061] For example, when the vehicle 3 is traveling through a tunnel, holes 5b and cracks 5c, for example, occur on the wall surface 5a inside the tunnel, as shown in FIG. 13 . When capturing images in a dark environment, such as inside a tunnel, a long exposure time causes blurring in the captured image in the direction of travel of the vehicle 3. Blur also occurs in captured images when capturing an image of a subject while the vehicle 3 is traveling at high speed. The blur correction mechanism 40 corrects the optical path of light incident on the imaging system 1A so as to reduce image blurring in the imaging area 9 even when the imaging device 11A captures an image while the vehicle 3 is moving. In this specification, the blurring that occurs when capturing an image from a moving vehicle 3 causes the subject to appear to flow in the opposite direction to the direction of travel in the captured image is referred to as "motion blur (image blur)."

[0062] As shown in FIG. 12A, an imaging device 11A according to the second embodiment includes a U-shaped arm 22 that supports a lens barrel 21 to which a lens 23 is attached so that the lens barrel 21 can rotate in the vertical direction.

[0063] As shown in FIGS. 11 and 12A , the imaging device 11A includes a blur correction mechanism 40 that rotates the lens barrel 21 around the Z axis based on a rotation command from the control device 15. The imaging device 11A may have, for example, a configuration in which the lens barrel 21 and the lens 23 are integrated, and the blur correction mechanism 40 rotates the lens barrel 21, the lens 23, and the arm 22 together around the rotation axis. The blur correction mechanism 40 may include, for example, a motor and gears. The blur correction mechanism 40 may utilize, for example, a pan rotation mechanism or a tilt rotation mechanism. Whether the pan direction rotation mechanism or the tilt direction rotation mechanism is associated with the blur correction mechanism 40 may be appropriately determined depending on the orientation of the imaging element 25 and the direction of the image capture target relative to the traveling direction of the vehicle 3. As a modified example, the imaging device 11A may be an imaging device 11Aa, as shown in FIG. 12B , that includes a camera 12 and a motor 41 that is separate from the camera 12 and rotates the camera 12. In addition to the illustrated lens 23, the camera 12 also includes a shutter 24, an image sensor 25, a camera control unit 27, and a focus mechanism 28. The camera 12 is attached to the output shaft of a motor 41 that serves as a shake correction mechanism 40, and the motor 41 rotates the camera 12 around the Z axis.

[0064] As shown in Fig. 11 , the imaging system 1A includes a speed detection device 10 that detects the moving speed of the vehicle 3. The speed detection device 10 is disposed on the vehicle 3 and can also detect that the vehicle 3 is moving. In the second embodiment, the speed detection device 10 detects the moving speed based on a vehicle speed pulse signal in which a pulse signal switches between ON and OFF for each fixed amount of rotation (rotation angle) of the axle of the vehicle 3. The speed detection device 10 sends the vehicle speed pulse signal together with the detected moving speed to the control device 15. In addition to this configuration, the speed detection device 10 may be, for example, a vehicle speed sensor that detects the moving speed from the rotation speed of the axle of the vehicle 3, or the detection of the moving speed may be performed by the control device 15 based on the vehicle speed pulse signal.

[0065] The blur correction mechanism 40 corrects the optical path of light L1, which is ambient light reflected by the imaging region 9, in accordance with the movement of the vehicle 3. That is, the blur correction mechanism 40 changes the optical path length between the imaging target and the imaging element 25 of the imaging device 11A. The blur correction mechanism 40 aligns the direction of light L1, which is ambient light reflected by the imaging region 9, with the imaging direction of the imaging element 25. Note that, although the blur correction mechanism 40 employs a configuration in which the lens barrel 21 rotates around the Z axis in the second embodiment, it may also be configured with a rotating mirror and a mirror driver, as described in International Publication No. WO 2023 / 002826.

[0066] Lens barrel 21 and arm 22 can be rotated, for example, in either a forward or reverse clockwise direction in a plan view, and the rotatable angular range may be less than 360 degrees or greater than 360 degrees. Blur correction mechanism 40 drives lens barrel 21 to rotate from an initial angle to a specified angle, and then returns it to the initial angle after rotating it to the specified angle.

[0067] The rotation angle of the lens barrel 21 during one frame period is limited by the mechanical constraints of the shake correction mechanism 40, and the lens barrel 21 can be rotated up to the maximum swing angle of the lens barrel 21 determined by this limitation.

[0068] Referring to Figure 13, motion blur correction by the blur correction mechanism 40 will be described. For example, suppose that the imaging system 1A, which is located at position A, moves to position B together with the vehicle 3 during the exposure time. In this case, if no blur correction is performed, the imaging area 9 moves relatively in the direction opposite to the traveling direction of the vehicle 3, resulting in an image in which the hole 5b moves relatively. In an image that continues to be exposed, the amount of pixel movement is detected as the amount of blur. In this way, the image captured by the imaging device 11 while the vehicle 3 is moving will be a blurred image.

[0069] Therefore, by rotating the lens barrel 21 during the exposure time in a direction that offsets the relative movement of the object to be imaged from the direction of travel, depending on the moving speed of the imaging system 1A and the vehicle 3, the imaging system 1A can image the same imaging area 9 during the exposure time and obtain an image with significantly reduced blur. In Figure 13, the lens barrel 21 is rotated counterclockwise so that the lens 23 of the lens barrel 21 rotates toward the object to be imaged during the exposure time. By rotating the lens barrel 21, the amount of movement of pixels in the captured image is corrected to zero.

[0070] 11 , the control device 15A includes a vehicle movement amount calculation unit 33 and a blur correction amount setting unit 34 in addition to the subject distance calculation unit 31 and the focus command unit 32. Note that the blur correction mechanism 40 may also include the blur correction amount setting unit 34.

[0071] The blur correction amount setting unit 34 calculates the swing angle α of the lens barrel 21 during imaging based on the moving speed V of the vehicle 3, the set exposure time Tp, the subject distance Lg, and the focal length F of the lens 23, in the following manner.

[0072] The focal length F is a value determined by the lens 23. The subject distance Lg is calculated in the same manner as in the first embodiment.

[0073] The movement amount Lp of the vehicle 3 during the exposure time Tp from the start time of imaging to the end time of imaging is calculated from the movement speed V and the exposure time Tp by the following formula (5): Lp [mm] = V [km / h] × 10 ６ × Tp [ms] / (60 ２ x10 ３ )...Equation (5)

[0074] The movement amount P of the pixels on the image sensor 25 from the start time of image capture to the end time of image capture is calculated from the movement amount Lp of the vehicle 3 and the subject magnification M using the following formula (6): P [mm] = Lp [mm] × M (6)

[0075] This pixel movement amount P causes motion blur, so to prevent motion blur, the optical path of light incident on the lens 23 is changed by a motion blur correction angle θ corresponding to the pixel movement amount P. The motion blur correction angle θ is calculated from the pixel movement amount P and focal length F using the following equation (7): θ [deg] = arctan (P / F) ... equation (7) The subject magnification M is calculated from the focal length F [mm] and subject distance Lg [m] using the following equation (8): M = F [mm] / (Lg [mm] × 10 ３ ) ... (8) From equations (5), (6), (7), and (8), θ = arctan(V × 10 ６ × Tp / (60 ２ x10 ３ ) / (Lg × 10 ３ )) = arctan(V×Tp / (Lg×60 ２ )) Equation (9) In this way, the motion blur correction angle θ is calculated from the motion speed V, the exposure time Tp, and the subject distance Lg.

[0076] The swing angle α of the lens barrel 21 required for motion blur correction during exposure is the same as the motion blur correction angle θ, so it is calculated using the following equation (10): α=θ (10) When motion blur correction is performed using a rotating mirror, the required swing angle α is half the motion blur correction angle θ, so it is calculated using the following equation (11): α=θ / 2 (11)

[0077] In this manner, the shake correction amount setting unit 34 calculates the swing angle α of the lens barrel 21 .

[0078] The image blur correction amount setting unit 34 calculates the rotation speed Vm of the lens barrel 21 during the exposure period based on the swing angle α of the lens barrel 21 and the exposure time Tp using the following formula: Vm=α / Tp1 (12)

[0079] Therefore, by rotating the lens barrel 21 in the opposite direction to the direction of movement at a rotation speed Vm after starting imaging, the imaging device 11A can receive light from the same imaging area 9 during the exposure time, thereby suppressing motion blur in the captured image.

[0080] Next, the operation of the imaging system 1A will be described with reference to Figs. 14 and 15. Fig. 14 is a flowchart showing the imaging process performed by the imaging system 1A. Fig. 15 is a graph showing the relationship between the exposure time, the motion blur correction angle, and the timing of distance measurement. Fig. 15(a) is a graph showing the moving speed of the vehicle 3 changing over time. Fig. 15(b) is a graph showing the timing of the exposure time for each frame. Fig. 15(c) is a graph showing the timing of distance measurement. Fig. 15(d) is a graph showing the change over time in the motion blur correction angle at which the blur correction mechanism 40 rotates the optical axis for motion blur correction.

[0081] Steps S1, S2, S5, and S6 are similar to the operations of the imaging system 1 of the first embodiment, and therefore description thereof will be omitted.

[0082] In step S11 , the speed detection device 10 detects the moving speed of the vehicle 3 and sends the detected moving speed to the control device 15 .

[0083] In step S12, as in step S3 in the first embodiment, the focus command unit 32 obtains the position of the focus lens 29 based on the received subject distance Lg, and in parallel, the shake correction amount setting unit 34 calculates the swing angle α as the shake correction amount based on the subject distance, the movement speed, and the exposure time, and calculates the rotation speed Vm of the lens barrel 21 based on the swing angle α.

[0084] In step S13, as in step S4 in the first embodiment, focus command unit 32 adjusts the focus of lens 23, and blur correction amount setting unit 34 causes blur correction mechanism 40 to rotate lens barrel 21 at the calculated rotation speed Vm, so that lens barrel 21 begins to rotate from a predetermined initial angle. This performs motion blur correction during image capture (exposure) by imaging device 11A. In this state, control device 15A continues to send a Hi signal instructing exposure to camera control unit 27 for exposure time Tp.

[0085] In the imaging device 11A, the camera control unit 27 opens the shutter 24 to expose the camera while receiving the Hi signal, thereby acquiring an image, and stores the acquired image in the storage unit 17. When the exposure time Tp has elapsed, the control device 15A continues to send a Low signal to the camera control unit 27 as an OFF signal instructing the camera to stop exposure. Note that a Low signal may be used as an ON signal instructing the camera to start exposure, and a Hi signal may be used as an OFF signal instructing the camera to stop exposure.

[0086] While camera control unit 27 is receiving the Low signal, control device 15A closes shutter 24, and control device 15A causes blur correction mechanism 40 to rotate lens barrel 21 in the reverse direction to return lens barrel 21 to its initial angle. Note that blur correction mechanism 40 may also rotate lens barrel 21 in the forward direction to return lens barrel 21 to its initial angle.

[0087] In synchronization with the timing at which the vehicle speed is detected, a Hi signal indicating an image capture command is transmitted and the first image is captured. At this time, the motion blur correction angle for the next frame is calculated using the speed of the vehicle 3 detected by the speed detection device 10. When the capture of the first image is completed, the blur correction mechanism 40 drives the lens barrel 21 to a rotation start angle β1, which is the rotation start position in the blur correction direction.

[0088] The blur correction mechanism 40 begins to rotate the lens barrel 21 at the rotation speed calculated by the blur correction amount setting unit 34. The control device 15A sends a Hi signal indicating an image capture instruction to the camera control unit 27, and the image capture device 11A captures an image. At this time, the image of the second frame is blur corrected at a motion blur correction angle θ1 corresponding to the speed V0 used when the immediately previous image was captured, and the third image is blur corrected at a motion blur correction angle θ2 corresponding to the speed V1 used when the second image was captured. Note that the motion blur correction angle for the fourth image may be calculated based on the average speed of the speed V1 used when the second image was captured and the speed V2 used when the third image was captured.

[0089] As described above, the imaging system 1A of the second embodiment further includes a blur correction mechanism 40 that acquires movement information of the vehicle 3 and corrects image blur along the traveling direction during imaging (exposure) of the imaging device 11A. The blur correction mechanism 40 corrects blur along the traveling direction during exposure of the imaging device based on the acquired distance information.

[0090] Distance information to the object to be imaged is acquired, and blurring in the traveling direction is corrected based on the distance information in accordance with the moving speed of the vehicle 3, so that clearer images with higher resolution can be acquired.

[0091] (Embodiment 3) An imaging system 1B according to embodiment 3 will be described with reference to Fig. 16 and Fig. 17. Fig. 16 is a block diagram showing the internal configuration of imaging system 1B according to embodiment 3. Fig. 17 is a flowchart showing imaging processing according to embodiment 3.

[0092] The imaging system 1B in the third embodiment has a configuration in which the configuration related to focus adjustment is removed from the imaging system 1A in the second embodiment. Except for this point and points described below, the imaging system 1B in the third embodiment has the same configuration as the imaging system 1A in the second embodiment.

[0093] The imaging system 1B in the third embodiment includes a lens 23 that does not allow focus adjustment. When a lens 23 with a large depth of field is used, an in-focus image can be captured without focus adjustment.

[0094] Next, the operation of the imaging system 1B in the third embodiment will be described with reference to Fig. 17. The operation of the imaging system 1B in the third embodiment is the same as the operation of the imaging system 1A in the second embodiment except that the operation related to focus adjustment is omitted. In the third embodiment, steps S1, S11, S2, S5, and S6 are the same as those in the imaging system 1A in the second embodiment, and therefore description thereof will be omitted.

[0095] In step S21, the shake correction amount setting unit 34 calculates the swing angle α as the shake correction amount based on the subject distance, the movement speed, and the exposure time, and calculates the rotation speed Vm of the lens barrel 21 based on the swing angle α.

[0096] In step S22, the blur correction amount setting unit 34 causes the blur correction mechanism 40 to rotate the lens barrel 21 at the calculated rotation speed Vm, and the lens barrel 21 begins to rotate from a predetermined initial angle. This performs motion blur correction during image capture by the imaging device 11A. In this state, the control device 15B continues to send a Hi signal instructing exposure to the camera control unit 27 for the exposure time Tp. Information about the distance to the image target is acquired, and blur correction in the traveling direction is performed based on the distance information in accordance with the moving speed of the vehicle 3, so that a clearer image with higher resolution can be acquired.

[0097] In this way, the imaging system 1B is installed on the vehicle 3 and captures an image of an imaging target that is at least a part of the surroundings of the moving vehicle 3 at a distance from the vehicle 3. The imaging system 1B includes an imaging device 11B that captures images of the imaging target over time or in accordance with the distance traveled by the vehicle 3, a ranging device 13 that acquires distance information to the imaging target using a ranging axis that does not pass through the lens 23 of the imaging device 11B, and a blur correction mechanism 40 that acquires movement information of the vehicle 3 and corrects image blur during imaging by the imaging device 11B. At least a portion of the ranging device 13 is installed at a position a predetermined distance Dv away from the imaging device 11B in the traveling direction of the vehicle 3. The ranging device 13 acquires distance information to the imaging target of the first image before the imaging device 11B captures the first image. The blur correction mechanism corrects image blur during imaging by the imaging device 11B based on the distance information.

[0098] Even when the subject distance changes for each image because the vehicle 3 is capturing images while it is traveling, the subject distance is detected with sufficient time before capturing images, ensuring responsiveness of image blur correction. This allows for more accurate tracking and highly accurate image blur correction. Note that in the third embodiment as well, the predetermined distance Dv may satisfy the condition of formula (2), or may further satisfy the condition of formula (3) in addition to the condition of formula (2). The conditions of formulas (2) and (3) are also valid for image blur correction.

[0099] (Other Embodiments) As described above, the above embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Therefore, other embodiments will be described below as examples.

[0100] In the above embodiment, information on the moving speed V1 from the speed detection device 10 of the vehicle 3 is used, but this is not limiting. The imaging system 1 may be provided with a speed detection device that detects the moving speed of the imaging system 1. The speed detection device may also use a GPS (Global Positioning System) system.

[0101] In the above embodiment, the imaging system 1 captures images of the wall surfaces on the sides of the vehicle 3, but this is not limiting. The imaging system 1 may capture images of the wall surfaces above and below the vehicle 3.

[0102] In the above embodiment, the mobile object is described as a vehicle 3 such as an automobile. However, the mobile object is not limited to a vehicle 3, and may be a ground vehicle such as a train or a motorcycle, a ship traveling on the sea, or an air vehicle such as an airplane or a drone. When the mobile object is a ship, the imaging system 1 captures images of the walls of bridge piers and bridge girders, and structures constructed along the shore. When the mobile object is a train, the position and wear of the overhead wires can be detected by capturing images of the overhead wires.

[0103] In the above embodiment, an image is captured using light that is ambient light reflected on the imaging region 9, but this is not limiting. Light may be irradiated from a moving body or an imaging system toward the imaging region 9, and an image may be captured using reflected light of the irradiated light.

[0104] (Summary of the Embodiments) (1) An imaging system according to the present disclosure is installed on a moving body and captures an image of an imaging target that is at least a part of the surroundings of the moving body at a distance from the moving body. The imaging system includes an imaging device that captures multiple images at successive imaging timings, a ranging device that acquires distance information to the next imaging target that the imaging device is scheduled to image along a ranging axis that does not pass through the optical elements of the imaging device, and a control device that controls the imaging device based on the distance information. The ranging device is installed a predetermined distance away from the imaging device in the direction of travel of the moving body.

[0105] As a result, even if the subject distance changes for each image because a plurality of images are taken at successive imaging timings while the moving body is moving, the subject distance is detected with sufficient time before imaging, so that it is possible to obtain a clear image by control based on distance information.

[0106] (2) In the imaging system of (1), the imaging device has a focus mechanism that focuses on the subject, the distance measuring device acquires distance information before the imaging device captures an image, and the control device controls the focus mechanism based on the distance information before capturing the image. Even if the subject distance changes for each image, the subject distance is detected with sufficient time before capturing, ensuring responsiveness of the focus control. This allows for the capture of clear images through highly accurate focus control.

[0107] (3) In the imaging system of (2), the distance measuring device acquires distance information for at least one point in the imaging area before the optical axis of the imaging device moves into the imaging area of ​​the imaging target due to the movement of the moving body.

[0108] (4) In any one of the imaging systems (1) to (3), the imaging device captures two images of two consecutive imaging areas of the imaging object, and the distance traveled by the moving object between capturing the two images is Lp, the imaging range of the imaging device in the direction of movement of the moving object is Ax, and the predetermined distance Dv between the imaging device and the distance measuring device satisfies Dv ≧ Lp − Ax / 2.

[0109] (5) In the imaging system of (4), the predetermined distance Dv satisfies Lp + Ax / 2 ≧ Dv.

[0110] (6) In the imaging system of (3) or (4), the control device calculates a subject distance from the imaging device to the imaging target based on the distance information.

[0111] (7) In the imaging system of (6), the distance measuring device acquires a plurality of pieces of distance information along the moving direction of the moving object, and the control device calculates the subject distance based on the plurality of pieces of distance information.

[0112] (8) In the imaging system of (7), the distance measuring device acquires a plurality of pieces of distance information along the traveling direction of the moving object with respect to the imaging area of ​​the first image.

[0113] (9) In the imaging system of (8), the control device calculates the subject distance based on the median value of the plurality of pieces of distance information.

[0114] (10) In the imaging system of (9), the control device calculates the subject distance based on distance information obtained by excluding distance information that differs from the median by a predetermined amount or more from the plurality of distance information.

[0115] (11) In the imaging system of (8), the control device calculates the subject distance based on the average value of multiple distance information, excluding distance information that is equal to or greater than a first predetermined value and distance information that is equal to or less than a second predetermined value that is smaller than the first predetermined value.

[0116] (12) In any one of the imaging systems (7) to (11), the control device calculates the subject distance of the (n+1)th image based on distance information of the imaging target from which the nth and (n+1)th image information is obtained.

[0117] (13) In the imaging system of any one of (7) to (12), the control device compares the subject distance with a first threshold value to determine whether to operate the focus mechanism.

[0118] (14) In any one of the imaging systems (7) to (13), the control device compares the absolute value of the change in the subject distance of the (n+1)th image relative to the subject distance of the nth image with a second threshold value, and adjusts the amount of operation of the focus mechanism.

[0119] (15) In any one of the imaging systems (1) to (14), the ranging device is installed with the ranging axis tilted at a predetermined angle perpendicular to the direction of travel of the moving body, and the control device calculates the subject distance based on the distance information acquired by the ranging device and the predetermined angle.

[0120] (16) In the imaging system of any one of (1) to (15), the distance measuring device is installed with the distance measuring axis tilted at a predetermined angle toward the traveling direction of the moving object with respect to the optical axis of the imaging device. The control device calculates the subject distance based on the distance information acquired by the distance measuring device and the predetermined angle.

[0121] (17) In the imaging system of any one of (2) to (14), the imaging device has a blur correction mechanism that acquires movement information of a moving object and corrects image blur during imaging by the imaging device. The distance measuring device acquires distance information before the imaging device captures an image, and the blur correction mechanism corrects image blur during imaging by the imaging device based on the distance information.

[0122] (18) The imaging system of (1) further includes a blur correction mechanism that acquires movement information of a moving object and corrects image blur during imaging by the imaging device. The ranging device acquires distance information before the imaging device captures an image, and the blur correction mechanism corrects image blur during imaging by the imaging device based on the distance information. (19) In the imaging system of (18), the imaging device captures two images of two consecutive imaging areas of an imaging target, and where Lp is the movement distance of the moving object between the capture of the two images, Ax is the imaging range of the imaging device in the movement direction of the moving object, and Dv is a predetermined distance between the imaging device and the ranging device, the predetermined distance Dv satisfies Dv ≧ Lp − Ax / 2. (20) In the imaging system of (19), the predetermined distance Dv satisfies Lp + Ax / 2 ≧ Dv.

[0123] The present disclosure is applicable to an imaging system installed on a moving vehicle.

[0124] REFERENCE SIGNS LIST 1, 1A, 1B Imaging system 3 Vehicle 4 Road 4b Hole 4c Crack 5 Wall 5a Wall surface 5b Hole 5c Crack 9 Imaging area 10 Speed ​​detection device 11, 11A, 11Aa, 11B Imaging device 13 Distance measurement device 15 Control device 17 Memory unit 19 Operation unit 21 Lens barrel 22 Arm 23 Lens 23a Optical axis 24 Shutter 25 Imaging element 27 Camera control unit 28 Focus mechanism 29 Focus lens 30 Focus motor 31 Subject distance calculation unit 32 Focus command unit 33 Vehicle movement amount calculation unit 34 Blur correction amount setting unit 40 Blur correction mechanism Df Distance information Lg Subject distance α Swing angle F Focal length M Subject magnification Tf Imaging interval V0, V1, V2, V3 movement speed

Claims

1. An imaging system that is installed on a moving body and captures an image of an object that is at least a part of the surroundings of the moving body and is away from the moving body while the moving body is in motion, comprising: an imaging device that captures multiple images at successive imaging timings; a ranging device that acquires distance information to the next object that the imaging device is scheduled to capture on a ranging axis that does not pass through the optical elements of the imaging device; and a control device that controls the imaging device based on the distance information, wherein the ranging device is installed a predetermined distance away from the imaging device in the direction of travel of the moving body.

2. The imaging system of claim 1, wherein the imaging device has a focus mechanism that focuses on the subject, the distance measuring device acquires the distance information before the imaging device captures the image, and the control device controls the focus mechanism based on the distance information before the image is captured.

3. The imaging system according to claim 2, wherein the distance measuring device acquires the distance information for at least one point in the imaging area before the optical axis of the imaging device moves into the imaging area of ​​the imaging target due to movement of the moving body.

4. The imaging system of claim 3, wherein the imaging device captures two images of two consecutive imaging areas of the imaging target, and the predetermined distance Dv satisfies Dv ≧ Lp − Ax / 2, where Lp is the distance the moving object moves between capturing the two images, Ax is the imaging range of the imaging device in the direction of movement of the moving object, and Dv is the predetermined distance between the imaging device and the distance measuring device.

5. The imaging system according to claim 4, wherein the predetermined distance Dv satisfies Lp + Ax / 2 ≧ Dv.

6. The imaging system according to claim 4, wherein the control device calculates a subject distance from the imaging device to the imaging target based on the distance information.

7. The imaging system according to claim 6, wherein the distance measuring device acquires a plurality of pieces of distance information along the direction of travel of the moving body, and the control device calculates the subject distance based on the plurality of pieces of distance information.

8. The imaging system according to claim 7, wherein the distance measuring device acquires the plurality of pieces of distance information along the traveling direction of the moving object with respect to the imaging area of ​​the first image.

9. The imaging system according to claim 8, wherein the control device calculates the subject distance based on a median value of the plurality of pieces of distance information.

10. The imaging system according to claim 9, wherein the control device calculates the subject distance based on distance information obtained by excluding, from among the plurality of pieces of distance information, distance information that differs from the median by a predetermined amount or more.

11. The imaging system according to claim 8, wherein the control device calculates the subject distance based on the average value of a plurality of distance information pieces excluding those that are equal to or greater than a first predetermined value and those that are equal to or less than a second predetermined value that is smaller than the first predetermined value.

12. The imaging system according to claim 7, wherein the control device calculates the subject distance of the (n+1)th image based on the distance information of the imaging target from which the nth and (n+1)th image information is acquired.

13. The imaging system according to claim 7, wherein the control device compares the subject distance with a first threshold value to determine whether or not to operate the focus mechanism.

14. The imaging system according to claim 7, wherein the control device compares the absolute value of the change in subject distance of the (n+1)th image relative to the subject distance of the nth image with a second threshold value, and adjusts the amount of operation of the focus mechanism.

15. The imaging system described in claim 1 or 2, wherein the distance measuring device is installed with the distance measuring axis tilted at a predetermined angle perpendicular to the direction of travel of the moving body, and the control device calculates the subject distance based on the distance information acquired by the distance measuring device and the predetermined angle.

16. The imaging system described in claim 1 or 2, wherein the distance measuring device is installed with the distance measuring axis tilted at a predetermined angle toward the direction of travel of the moving object relative to the optical axis of the imaging device, and the control device calculates the subject distance based on the distance information acquired by the distance measuring device and the predetermined angle.

17. An imaging system as described in any one of claims 2 to 14, wherein the imaging device has a blur correction mechanism that acquires movement information of the moving object and corrects image blur during imaging by the imaging device, the distance measuring device acquires the distance information before the imaging device captures the image, and the blur correction mechanism corrects image blur during imaging by the imaging device based on the distance information.

18. The imaging system of claim 1, wherein the imaging device has a blur correction mechanism that acquires movement information of the moving object and corrects image blur during imaging by the imaging device, the distance measuring device acquires the distance information before the imaging device captures the image, and the blur correction mechanism corrects image blur during imaging by the imaging device based on the distance information.

19. The imaging system of claim 18, wherein the imaging device captures two images of two consecutive imaging areas of the imaging target, and the predetermined distance Dv satisfies Dv ≧ Lp − Ax / 2, where Lp is the distance the moving object moves between capturing the two images, Ax is the imaging range of the imaging device in the direction of movement of the moving object, and Dv is the predetermined distance between the imaging device and the distance measuring device.

20. The imaging system according to claim 19, wherein the predetermined distance Dv satisfies Lp + Ax / 2 ≧ Dv.

Images