JP6659929B2 - Road surface photographing system - Google Patents

Description

  The present invention relates to a road surface photographing system for photographing a road mainly for inspection of the road surface.

  2. Description of the Related Art Conventionally, an inspection method for inspecting a road or the like by scanning and detecting infrared rays radiated from a road or the like by moving a vehicle equipped with an infrared detector is known (for example, see Patent Document 1). ). However, the inspection using infrared rays has a disadvantage that good inspection results cannot be obtained (for example, see paragraph 0008 of Patent Document 2).

  Therefore, there is known a technique for improving the defect detection accuracy by using a video camera and an electromagnetic wave radar in addition to the infrared detector (for example, see Patent Document 2).

JP-A-60-89740 JP-A-2002-257744

  However, the electromagnetic wave radar used in the technique described in Patent Document 2 has a disadvantage that the cost of an inspection system for inspection increases because the cost is high.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a road and road surface photographing system that can easily reduce costs while improving inspection accuracy by infrared rays.

  The road surface imaging system according to the present invention is mounted on a vehicle traveling on a road surface in a predetermined first direction, an infrared image capturing unit that captures an image of the road surface using infrared light as an infrared image, A mileage detecting unit that detects a mileage of the vehicle, and an image is executed by the infrared imaging unit each time the vehicle travels a predetermined reference distance based on the mileage detected by the mileage detecting unit. An infrared image processing unit that generates an infrared road surface image by performing image processing on the infrared captured image captured by the infrared image capturing unit. The length of the imaging range of the road surface in the first direction is multiplied by a preset set number of the reference distance, the set number is a natural number of 2 or more, and the image processing is performed by the red processing. A plurality of directly-facing images based on the plurality of infrared-captured images continuously captured by the image capturing unit and corresponding to the road surface correspond to the first direction on each of the directly-facing images. And a superimposition process of superimposing on each of the directly-facing images while shifting by a reference image length, which is a length corresponding to the reference distance on the road surface, along the second direction that is the direction in which the road surface moves.

  According to this configuration, since the infrared road surface image can be obtained by superimposing a plurality of infrared imaging images obtained by imaging the road surface with infrared light while the vehicle is traveling, the accuracy of the infrared road surface image is improved. Can be improved. Further, since it is not necessary to use an electromagnetic wave radar as in the background art, it is easy to reduce the cost. In addition, the plurality of superimposed infrared captured images are captured by the infrared image capturing unit each time the vehicle travels a preset reference distance, so that a plurality of superimposed infrared captured images is obtained. Therefore, there is no need to provide a plurality of imaging units.

  In addition, the imaging direction of the infrared image capturing unit is inclined with respect to a perpendicular to the road surface, and the image processing is performed on each of the infrared captured images continuously captured by the infrared image capturing unit. It is preferable to include a facing conversion process of converting the image into the facing image by homography conversion.

  According to this configuration, it is easy to increase the imageable road surface area by attaching the infrared image capturing unit obliquely to the vehicle.

  The image processing apparatus further includes a visible image capturing unit attached to the vehicle and configured to capture an image of the road surface using visible light as a visible captured image, wherein the image capturing control unit is configured to perform a process based on a travel distance detected by the travel distance detection unit. Preferably, the imaging by the visible image imaging unit is performed in synchronization with the infrared image imaging unit.

  According to this configuration, since the image of the road surface with visible light is captured as the visible image, the road inspection accuracy can be easily improved by using both the visible image of visible light and the infrared image of infrared light. become. In addition, since the image pickup by the visible image pickup unit is synchronized with the infrared image pickup unit, it becomes easy to compare the images at the same image pickup position between the visible image pickup image and the infrared image pickup image.

  The traveling distance detection unit outputs a pulse signal each time the vehicle travels a preset distance, and the imaging control unit performs imaging by the infrared imaging unit based on the pulse signal. It is preferable to synchronize the imaging with the visible image imaging unit.

  According to this configuration, the imaging by the infrared imaging unit and the imaging by the visible imaging unit are synchronized based on the pulse signal. Therefore, the imaging by the infrared imaging unit and the imaging by the visible imaging unit are synchronized. Is easy.

  It is preferable that the display device further includes a display unit that displays the infrared road surface image and the visible captured image so that the captured positions of the road surface correspond to each other.

  According to this configuration, the infrared road surface image and the visible captured image are displayed so that the captured road surface positions correspond to each other, so that the visible captured image and the infrared captured image have the same imaging position. As a result of comparing the images, it is easy to improve the road inspection accuracy.

  Preferably, the vehicle further includes the vehicle.

  According to this configuration, the road and road surface imaging system is configured to include the vehicle.

  The road surface photographing system having such a configuration can easily reduce the cost while improving the inspection accuracy by infrared rays.

FIG. 1 is an explanatory diagram conceptually showing a configuration of a road surface photographing system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram for describing a relationship between an imaging range illustrated in FIG. 1 and a length, a reference distance, and a set number in a direction along a traveling direction of the imaging range. FIG. 9 is an explanatory diagram for describing a facing conversion process of the infrared image processing unit. FIG. 9 is an explanatory diagram for describing a superimposition process performed by an infrared image processing unit. FIG. 4 is a screen diagram illustrating an example of an infrared road surface image displayed on a display screen of a display by a display processing unit and a visible captured image.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each of the drawings, configurations denoted by the same reference numerals indicate the same configurations, and the description thereof will be omitted. FIG. 1 is an explanatory view conceptually showing the configuration of a road surface photographing system according to one embodiment of the present invention.

  A road / road surface photographing system 1 shown in FIG. 1 includes a vehicle 2, an infrared thermography camera 3 (infrared image capturing unit), a line sensor camera 4 (visible image capturing unit), a mileage detecting unit 5, an image capturing control unit 6, and a computer 7. , And a display 8 (display unit).

  The vehicle 2 runs on the road surface RS of the road R. In the example illustrated in FIG. 1, the left direction in the drawing is the traveling direction D1 (first direction) of the vehicle 2. The road R is, for example, a highway. The road R is configured by stacking a floor slab R3, a waterproof layer R2, and a surface layer R1 in this order. The surface layer R1 is asphalt, the waterproof layer R2 is a layer of a material (for example, a resin sheet) that is impermeable to water, and the floor slab R3 is a concrete plate. In addition, a roadbed may be provided instead of the floor slab R3.

  The infrared thermography camera 3 is a camera that captures an image using infrared light. The infrared thermography camera 3 performs imaging at a pulse timing of a pulse signal P3 described later. The infrared thermography camera 3 is attached to the vehicle 2, for example, at the upper rear end. The imaging direction 31 of the infrared thermography camera 3 is directed rearward and obliquely downward from the upper rear end of the vehicle 2. The imaging direction 31 is a line connecting the optical axis direction of the optical system of the infrared thermography camera 3 or the center of the imaging range 32 of the infrared thermography camera 3 and the infrared thermography camera 3.

  The imaging direction 31 is inclined with respect to the perpendicular RV of the road surface RS. The length La of the imaging range 32 of the road surface RS in the direction along the traveling direction D1 is, for example, 1 m. It is preferable that the width of the imaging range 32 in the direction orthogonal to the traveling direction D1 is larger than the width of the road surface RS (the width of the lane in which the vehicle 2 is traveling).

  As described above, the infrared thermography camera 3 is attached to the upper rear end of the vehicle 2, and the imaging direction 31 is inclined with respect to the perpendicular RV of the road surface RS, so that the length La is increased and the image is taken by the infrared thermography camera 3. The area of the road surface RS can be increased. In addition, the infrared thermography camera 3 may be attached to the upper end of the front end of the vehicle 2, and the imaging direction 31 may be directed forward and obliquely downward. Further, the infrared thermography camera 3 is not limited to an example constituted by a single camera. The infrared thermography camera 3 may be configured by combining a plurality of cameras, and the imaging ranges of the plurality of cameras may be combined to form the imaging range 32.

  The line sensor camera 4 is a camera that captures an image of visible light in a line. The line sensor camera 4 performs imaging at a pulse timing of a pulse signal P4 described later. The line sensor camera 4 is provided, for example, so as to protrude rearward from the rear end of the vehicle 2, and captures images downward.

  The line sensor camera 4 captures the road surface RS as a visible image in a line shape extending in a direction perpendicular to the traveling direction D1 (a depth direction in the drawing). In the imaging range of the line sensor camera 4, the length Lb in the direction along the traveling direction D1 is, for example, 1 mm. The width of the imaging range of the line sensor camera 4 in the direction orthogonal to the traveling direction D1 may be larger than the width of the road surface RS (the width of the lane in which the vehicle 2 is traveling), similarly to the infrared thermography camera 3. preferable.

  Note that the line sensor camera 4 may be provided on the front end side of the vehicle 2. Further, the line sensor camera 4 is not limited to an example constituted by a single camera. The line sensor camera 4 may be configured by combining a plurality of cameras, and the imaging range of the line sensor camera 4 may be configured by connecting the imaging ranges of the plurality of cameras.

  The traveling distance detection unit 5 is disposed, for example, below the vehicle body of the vehicle 2 so as to face the road surface RS. The traveling distance detector 5 detects the traveling distance of the vehicle 2. Specifically, the traveling distance detection unit 5 detects the traveling distance of the vehicle 2 by, for example, outputting a pulse signal P5 every time the vehicle 2 travels a preset distance Ls. The set distance Ls is, for example, 10 mm. That is, the traveling distance detector 5 outputs the pulse signal P5 every time the vehicle 2 travels 10 mm.

  As the traveling distance detection unit 5, for example, a commercially available non-contact velocimeter can be used, and for example, a non-contact velocimeter LC-5200 manufactured by Ono Sokki Co., Ltd. can be used. The traveling distance detection unit 5 only needs to be able to detect the traveling distance of the vehicle 2, and is not necessarily output a pulse signal every time the vehicle travels the set distance Ls.

  The imaging control unit 6 causes the infrared thermography camera 3 to execute imaging each time the vehicle 2 travels a preset reference distance Lc based on the pulse signal P5 output from the traveling distance detection unit 5. In addition, the imaging control unit 6 causes the line sensor camera 4 to perform imaging in synchronization with the imaging by the infrared thermography camera 3 based on the pulse signal P5.

  Specifically, the imaging control unit 6 includes a multiplying circuit for multiplying the pulse train of the pulse signal P5 and a frequency dividing circuit for dividing the frequency. The imaging control unit 6 generates a pulse signal P3 by dividing the pulse train of the pulse signal P5 by 10, for example, and outputs the pulse signal P3 to the infrared thermography camera 3. The pulse signal P5 is a pulse output every time the vehicle 2 travels 10 mm, and one pulse corresponds to 10 mm, so one pulse of the pulse signal P3 corresponds to 100 mm. In this case, since the pulse signal P3 is a signal obtained by dividing the frequency of the pulse signal P5, the pulse timings of the pulse signal P3 and the pulse signal P5 are synchronized.

  In addition, the imaging control unit 6 generates a pulse signal P4 by multiplying the pulse train of the pulse signal P5 by 10, for example, and outputs the pulse signal P4 to the line sensor camera 4. Since one pulse of the pulse signal P5 corresponds to 10 mm, one pulse of the pulse signal P4 corresponds to 1 mm. In this case, since the pulse signal P4 is a signal obtained by multiplying the pulse signal P5, the pulse timings of the pulse signal P4 and the pulse signal P5 are synchronized. Therefore, since the pulse signals P3 and P4 are both synchronized with the pulse signal P5, the pulse signals P3 and P4 are also synchronized with each other.

  Since the infrared thermography camera 3 performs imaging at the pulse timing of the pulse signal P3, the infrared thermography camera 3 performs imaging each time the vehicle 2 travels 100 mm. That is, the reference distance Lc is set to 100 mm by the frequency dividing circuit of the imaging control unit 6. Since the length La of the imaging range 32 in the direction along the traveling direction D1 is 1 m as described above, the length La is set to ten times the reference distance Lc. That is, the preset set number Ns is set to 10, the set number Ns is a natural number of 2 or more, and the length La is set to be the set number Ns times the reference distance Lc.

  FIG. 2 is an explanatory diagram for explaining the relationship between the imaging range 32 shown in FIG. 1 and the length La, the reference distance Lc, and the set number Ns. As shown in FIG. 2, the imaging range 32 of the infrared thermography camera 3 has a length La of 1 m in the traveling direction D1 and a reference distance Lc that is shifted every time of imaging is 100 mm. The range of −100 mm = 90 mm overlaps.

  Then, when the imaging is repeated ten times, the infrared image at the position A1 of the road surface RS is imaged ten times (the set number Ns), as indicated by reference numeral a1. Thereafter, as indicated by reference numerals a2 to a10, the infrared images at the positions A2 to A10 of the road surface RS are respectively captured 10 times (the set number Ns). Thus, according to the road and road surface imaging system 1, the infrared image at the same position on the road surface RS can be imaged a set number Ns times while the vehicle 2 is traveling.

  Note that in the range where the travel distance from the start of imaging is equal to or less than the set number Ns-1 times the reference distance Lc, that is, in the position range where the travel distance from the start of imaging is 100 mm × 9 = 900 mm or less, the number of times of imaging is nine. Times or less. Therefore, image data captured in a range where the traveling distance from the start of the imaging is less than the set number Ns times of the reference distance Lc may be deleted, or may be used as reference data with low image accuracy.

  On the other hand, since the line sensor camera 4 performs imaging at the pulse timing of the pulse signal P4, the line sensor camera 4 captures an image every time the vehicle 2 travels 1 mm. Further, as described above, the length Lb of the imaging range of the line sensor camera 4 in the direction along the traveling direction D1 is 1 mm. That is, the length Lb of the imaging range along the traveling direction D1 is made equal to the shift amount of the imaging position that is shifted each time imaging is performed by the multiplying circuit of the imaging control unit 6. Thus, the line sensor camera 4 generates a visible captured image Gk by continuously capturing the visible light image of the road surface RS so as to scan the visible light image.

  Since the pulse signal P3 and the pulse signal P4 are synchronized with each other, the imaging timings of the line sensor camera 4 and the infrared thermography camera 3 are also synchronized. Therefore, it is easy to associate the images captured at the same position with the visible light image captured by the line sensor camera 4 and the infrared image captured by the infrared thermography camera 3.

  The display 8 is a so-called display device such as a liquid crystal display device. The display unit is not limited to the display device. For example, a printer that displays an image by printing on a paper medium may be used.

  As the computer 7, various computers such as a so-called personal computer can be used. The computer 7 is, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a RAM (Random Access Memory) that temporarily stores data, and a non-volatile storage unit that stores a predetermined control program and the like. The system includes an HDD (Hard Disk Drive), an interface circuit for receiving image data output from the infrared thermography camera 3 and the line sensor camera 4, and peripheral circuits thereof. The computer 7 functions as an infrared image processing unit 71, an image storage unit 72, and a display processing unit 73, for example, by executing a control program stored in the HDD.

  The infrared image processing unit 71 performs a facing conversion process and a superposition process. The facing conversion process is a process of converting each infrared captured image G1 continuously captured by the infrared thermography camera 3 into a facing image G2 by homography conversion. The superimposition process is performed on each of the directly-facing images G2 along a traveling direction D2 (second direction) that is a direction corresponding to the traveling direction D1 on each of the directly-facing images. Is a process of superimposing while shifting the reference image length Lg corresponding to the reference distance Lc on the road surface RS.

  FIG. 3 is an explanatory diagram for describing the facing conversion process of the infrared image processing unit 71. Since the imaging direction 31 of the infrared thermography camera 3 is inclined with respect to the perpendicular RV of the road surface RS, the actual imaging range 32 with respect to the ground has a trapezoidal shape as shown in (1). When the image of the trapezoidal imaging range 32 is captured by the infrared thermography camera 3, an infrared captured image G1 having a rectangular outer shape as shown in (2). As a result, the image of the road surface RS to be inspected has a shape in which the distance becomes narrow as in the so-called perspective method. Therefore, the scale magnification of the actual road surface RS and the image of the road surface RS shown in the infrared image G1. Varies depending on the image position of the road surface RS.

  However, in order to perform the superimposition process, it is necessary to superimpose images of a plurality of infrared captured images G1 that are captured while shifting the capturing positions unless the scale magnifications of the images captured at the same position are the same. Can not. Therefore, it is assumed that the virtual camera V directly captures an image of the road surface RS, that is, the virtual camera V whose imaging direction is perpendicular to the road surface RS. Then, as shown in (3), the infrared captured image G1 is converted into a directly-facing image G2 obtained when the road surface RS is captured by such a virtual camera V.

  The infrared image processing unit 71 converts the infrared captured image G1 into a directly-facing image G2 using an image processing method known as homography conversion (homography). The infrared image processing unit 71 may convert the infrared image G1 into the directly-facing image G2 each time the infrared image G1 is captured by the infrared thermography camera 3, and temporarily store the plurality of infrared images G1 in the storage unit. Alternatively, each infrared captured image G1 may be read from the storage unit and converted to the directly-facing image G2 later.

  Next, the superposition processing will be described. FIG. 4 is an explanatory diagram for describing a superposition process performed by the infrared image processing unit 71. The outer edge of the facing image G2 illustrated in FIG. 4 corresponds to the imaging range 32.

  The infrared image processing unit 71 converts the plurality of facing images G2 obtained by the facing conversion process by the superimposition process into a reference image length in the traveling direction D2 in the order in which the original infrared captured image G1 was captured. An infrared road surface image G3 is generated by superimposing the images while shifting each Lg. In this case, the range in which the travel distance from the start of imaging is less than or equal to the set number Ns-1 times the reference distance Lc, that is, the position range in which the travel distance from the start of imaging is 100 mm × 9 = 900 mm or less, is positive. Since the number of pairs of images G2 is less than the set number Ns, the image corresponding to this range may be deleted, or may be used as reference data with low image accuracy.

  In a range where the traveling distance from the start of the imaging exceeds the set number Ns-1 times the reference distance Lc, that is, in a position range where the traveling distance from the start of the imaging exceeds 900 mm, the correct value of the road surface RS at that position is taken. The paired images G2 are superimposed by the set number Ns.

  The superimposition may be a process of integrating respective pixel values at corresponding positions with respect to each of the facing images G2 while being shifted by the reference image length Lg, and averaging the pixel values. Is also good. As described above, the infrared road surface image G3 is obtained by superimposing a plurality of (set number Ns) pixel values corresponding to the same position on the road surface RS with respect to the plurality of facing images G2.

  With reference to FIG. 1, the image storage unit 72 stores the infrared road surface image G3 generated by the infrared image processing unit 71 and the visible captured image Gk captured by the line sensor camera 4 in the storage unit. The display processing unit 73 reads the infrared road surface image G3 and the visible captured image Gk from the storage unit, and causes the display 8 to display the captured road surface RS such that the positions of the road surface RS correspond to each other. At this time, since the infrared road surface image G3 and the visible image Gk are imaged at synchronized timing based on the pulse signal P5, it is easy to make the mutual positional relationship correspond.

  In the process of generating the infrared road surface image G3, if a portion where the number of superimposed images is less than the set number Ns is deleted, the head portion of the visible captured image Gk may be deleted by a corresponding length. In addition, in the process of generating the infrared road surface image G3, if a portion where the number of superimposed images is less than the set number Ns is not deleted, the infrared road surface image G3 and the visible captured image Gk may be used as they are. Thus, by aligning the head position of the infrared road surface image G3 and the head position of the visible captured image Gk, it is possible to make the mutual positional relationship correspond.

  FIG. 5 is a screen diagram illustrating an example of the infrared road surface image G3 and the visible captured image Gk displayed on the display screen Gd of the display 8 by the display processing unit 73. In the example illustrated in FIG. 5, the infrared road surface image G3 and the visible captured image Gk are associated with each other by arranging the positional relationship between them vertically. Incidentally, the correspondence of the positional relationship may be arranged side by side and left or right, or the infrared road surface image G3 and the visible image Gk may be displayed in a superimposed manner.

  First, when viewing the visible image Gk captured by the line sensor camera 4 with visible light, substantially rectangular images B1 and B2 and linear images B3 and B4 are shown. The images B1 and B2 are after repairing the surface layer R1 of the road R and are not defects of the road R. On the other hand, the images B3 and B4 are likely to be road cracks. As described above, according to the visible captured image Gk, the state of the road surface RS such as repair marks and cracks on the surface layer R1 can be confirmed.

  Next, when an infrared road surface image G3 based on the infrared captured image G1 captured by the infrared thermographic camera 3 is viewed, a rectangle similar to the images B1 and B2 is located at a position corresponding to the images B1 and B2 of the visible captured image Gk. Images B5 and B6 are recognized. In the images B5 and B6, the temperature difference generated because the repair material used for repairing the surface layer R1 is different from the other portions appears as the images B5 and B6 of the infrared image G1. Thus, by comparing the infrared road surface image G3 with the visible image Gk, it can be determined that the images B5 and B6 are not defects of the road R.

  On the other hand, black shadow-like images B7 and B8 appear at the position of the infrared road surface image G3 corresponding to the images B3 and B4 of the visible captured image Gk. In this case, it can be determined that a defect such as rainwater that has permeated into the surface layer R1 from a crack in the road R has accumulated on the waterproof layer R2 or a cavity has been formed due to erosion of the rainwater. Even when image unevenness such as images B9 to B11, that is, temperature unevenness occurs, it can be determined that defects such as erosion of surface layer R1 and cracks of floor slab R3 have occurred.

  As described above, according to the road surface photographing system 1, the infrared road surface image G3 is generated by superimposing the plurality of infrared captured images G1. The slight difference in the infrared level is increased, so that the defect can be easily confirmed in the infrared road surface image G3. When the pixels are superimposed by averaging the pixel values, the noise component of the infrared captured image G1 is canceled. As a result, the image generated by the original road defect is displayed with high accuracy, and the defect can be easily confirmed.

  In addition, since the infrared road surface image G3 and the visible image Gk can be compared with each other and the images can be confirmed, it is possible to confirm the defect state of the road in more detail.

  As described above, according to the road and road surface imaging system 1, the inspection accuracy by infrared rays can be improved. Also, unlike the related art, it is not necessary to use the electromagnetic wave radar, so that the cost can be easily reduced.

  Although the example in which the computer 7 and the display 8 are mounted on the vehicle 2 has been described, the computer 7 and the display 8 do not necessarily have to be mounted on the vehicle 2. For example, the computer 7 and the display 8 may be installed in a building outside the vehicle 2. In this case, the infrared captured image G1 and the visible captured image Gk may be stored in a storage medium and supplied to the computer 7, or may be transmitted to the computer 7 using wireless communication means or the like. The computer 7 may be configured to generate an infrared road surface image G3 from the infrared captured image G1 and the visible captured image Gk thus obtained, and display the infrared road surface image G3 and the visible captured image Gk on the display 8. . Alternatively, a part of the computer 7 and the display 8 may be installed in a building outside the vehicle 2. For example, the display processing unit 73 and the display 8 may be installed in a building outside the vehicle 2. Then, the infrared road surface image G3 and the visible captured image Gk may be supplied to the display processing unit 73 by a storage medium or a wireless communication unit.

  In addition, the road surface photographing system 1 does not necessarily need to include the line sensor camera 4, and may be configured not to display the visible photographed image Gk. In addition, the imaging direction 31 of the infrared thermography camera 3 does not necessarily need to be inclined with respect to the perpendicular RV of the road surface RS, and the infrared thermography camera 3 is disposed so as to face the road surface RS, and the imaging direction 31 is set. It may coincide with the perpendicular RV of the road surface RS. In this case, the infrared image processing unit 71 does not need to execute the facing conversion process, and can use the infrared captured image G1 as it is as the facing image G2.

DESCRIPTION OF SYMBOLS 1 Road surface photographing system 2 Vehicle 3 Infrared thermography camera (infrared image pickup part)
4 Line sensor camera (visible image pickup unit)
5 running distance detection unit 6 imaging control unit 7 computer 8 display (display unit)
31 imaging direction 32 imaging range 71 infrared image processing unit 72 image storage unit 73 display processing unit D1 running direction (first direction)
D2 Running direction (second direction)
G1 Infrared captured image G2 Facing image G3 Infrared road surface image Gd Display screen Gk Visible captured image Lc Reference distance Lg Reference image length Ls Set distance Ns Set number P3, P4, P5 Pulse signal R Road R1 Surface R2 Waterproof layer R3 Floor slab RS Road surface RV Vertical line V Virtual camera

Claims (6)

An infrared image capturing unit attached to a vehicle traveling on a road surface in a predetermined first direction, and capturing an infrared image of the road surface as an infrared captured image.
A traveling distance detection unit that detects a traveling distance of the vehicle,
Based on the running distance detected by the travel distance detection unit, said each time a vehicle is the reference distance travel is preset by the infrared imaging unit once a predetermined imaging range, shooting imaging control unit for an image When,
An infrared image processing unit that generates an infrared road surface image by performing image processing on the infrared captured image captured by the infrared image capturing unit ,
Mounted on the vehicle, an image of visible light of the road surface, e Bei a visible image capturing unit that captures a visible captured images,
A road control unit configured to cause the visible image capturing unit to perform imaging in synchronization with the one-time imaging by the infrared image capturing unit based on the traveling distance detected by the traveling distance detection unit; Shooting system. The length of the imaging range of the road surface by the infrared image capturing unit, the length in the first direction is set to a preset multiple of the reference distance, the set number is a natural number of 2 or more,
  The image processing is based on the plurality of infrared captured images continuously captured by the infrared image capturing unit and, on each of the directly-facing images, a plurality of directly-facing images that are images directly facing the road surface. In the second direction, which is the direction corresponding to the first direction, on each of the directly-facing images, the image is overlapped while being shifted by a reference image length that is a length corresponding to the reference distance on the road surface. The road surface photographing system according to claim 1 including processing. The imaging direction of the infrared image imaging unit is inclined with respect to a perpendicular to the road surface,
The image processing according to each of the infrared image captured in succession by said infrared imaging unit, to claim 1 or 2 including a confronting conversion processing for converting the confronting images by homography transformation Road surface shooting system. The travel distance detection unit outputs a pulse signal each time the vehicle travels a preset set distance,
The imaging control unit according to claim 1, to synchronize the imaging based on the pulse signal with the imaging of each of the one by the infrared imaging unit by the visible image capturing unit Road surface imaging system. The road surface photographing system according to any one of claims 1 to 4, further comprising a display unit configured to display the infrared road surface image and the visible image so that positions of the photographed road surface correspond to each other. .   The road surface photographing system according to claim 1, further comprising the vehicle.