Method for creating ground model and ground model creation system

Abstract

To provide a method that enables easy investigation of a road condition at the time of starting repair work when repairing a road.SOLUTION: The method includes: a coordinate acquisition step of acquiring three-dimensional coordinates of a plurality of feature points; an imaging step of capturing a plurality of captured images by a camera 3 such that each of the plurality of feature points is included in at least two captured images; and an ortho image creation step of creating an ortho image having a ground pixel size of 5 millimeters or less on the basis of the three-dimensional coordinates of the feature points acquired by the coordinate acquisition step and the plurality of captured images captured by the imaging step.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an orthoimage creation method and an orthoimage creation system that create orthoimages based on images taken from the sky, for example, by an unmanned aerial vehicle, and also to a ground model creation method and a ground model creation system that create a ground model using the orthoimages. [Background technology]

[0002] Conventionally, when damage such as cracks occurs on the surface of the asphalt pavement that makes up the surface layer of a road, the road needs to be repaired.

[0003] In order to repair a road, various investigations are conducted, such as investigating the road condition at the time of commencement of repair work and the positions of planar elements including road edges and lane markings. For example, investigations are conducted into the locations of cracks on the road and the amount of cracks. Conventionally, investigations into the condition of cracks have been conducted visually by inspectors, but the work of inspecting the road and detecting cracks by each inspector is extremely cumbersome. Therefore, instead of inspectors detecting cracks, road conditions are sometimes investigated using a dedicated road surface property measurement vehicle (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-123510 Summary of the Invention [Problem to be solved by the invention]

[0005] When investigating road conditions using a dedicated road surface property measurement vehicle, the vehicle must be driven, but on narrow roads, the vehicle cannot drive and it is impossible to inspect the road conditions.

[0006] In addition, the positions of planar elements, including road edges and lane markings, in the repair area where repairs are to be performed, are surveyed. Conventionally, a large number of planar positions on the road edges and lane markings are surveyed, and planar elements, including road edges and lane markings, are mapped based on each planar position. Therefore, in order to map the planar elements, it is necessary to survey a large number of planar positions, which is very cumbersome.

[0007] If there is a manhole in the repair area, an investigation is conducted into the manhole adjustment height. The investigation into the manhole adjustment height involves investigating the adjustment height (the difference in elevation between the elevation at the time of repair work commencement and the elevation of the repair plan surface) for each position in the longitudinal and transverse directions of the manhole.

[0008] Conventionally, the elevation of each horizontal position around the manhole is detected based on the vertical and horizontal sections of the road that pass through each horizontal position, and the adjustment height is calculated from the difference in elevation between that elevation and the elevation of the repair plan surface. Therefore, it is necessary to detect the elevation of each horizontal position based on the vertical and horizontal sections of the road for each manhole, which is very cumbersome.

[0009] The present invention has been made with an eye on such problems, and aims to provide an orthoimage creation method, a ground model creation method, an orthoimage creation system, and a ground model creation system that make it possible to easily investigate the road condition at the time of starting repair work when repairing a road. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention takes the following measures.

[0011] That is, the orthoimage creation method of the present invention is characterized by comprising a coordinate acquisition step of acquiring three-dimensional coordinates for a plurality of feature points, a photographing step of capturing a plurality of photographic images using a photographing device so that each of the plurality of feature points is included in at least two photographic images, and an orthoimage creation step of creating an orthoimage with a ground pixel size of 5 millimeters or less based on the three-dimensional coordinates of each feature point acquired in the coordinate acquisition step and the plurality of photographic images captured in the photographing step.

[0012] The orthoimage creation system according to the present invention is characterized by comprising: a coordinate storage means for storing three-dimensional coordinates for a plurality of feature points; a photographed image storage means for storing a plurality of photographed images taken by an imaging device so that each of the plurality of feature points is included in at least two photographed images; and an orthoimage creation means for creating an orthoimage with a ground pixel size of 5 millimeters or less based on the three-dimensional coordinates of each feature point stored in the coordinate storage means and the plurality of photographed images stored in the photographed image storage means.

[0013] As a result, the orthoimage creation method and orthoimage creation system of the present invention can create orthoimages with a ground pixel size of 5 millimeters or less, making it possible to create orthoimages that clearly show the condition of the road surface and the location of planar elements around the road.The orthoimages created by the present invention can clearly identify areas where cracks have occurred or areas where patching has occurred on the road.Therefore, since there is no need to run a dedicated road surface property measurement vehicle to investigate the condition of cracks on the road surface, it is possible to investigate road conditions regardless of road width.

[0014] Furthermore, in the orthoimages created by the present invention, the positions of planar elements including road edges, lane markings, etc. can be clearly identified. Therefore, since it is not necessary to conduct surveys at a large number of planar positions in order to plot planar elements including road edges, lane markings, etc., planar elements can be easily plotted based on the orthoimages.

[0015] Furthermore, the orthoimage created by this invention makes it possible to detect the longitudinal and transverse planar positions of the area surrounding the manhole. Therefore, after identifying the longitudinal and transverse planar positions of the area surrounding the manhole, the elevation of each planar position can be extracted from the point cloud data acquired by the 3D scanning device. Therefore, there is no need to create longitudinal and transverse road sections for each manhole in order to detect the elevation of each longitudinal and transverse planar position of the area surrounding the manhole. Therefore, it is possible to easily detect the manhole adjustment height.

[0016] In the orthoimage creation method according to the present invention, the photographing device is a photographing device located at an altitude of 20 meters or less above the ground.

[0017] In the orthoimage creation system according to the present invention, the photographing device is a photographing device located at an altitude of 20 meters or less above the ground.

[0018] As a result, the orthoimage creation method and orthoimage creation system according to the present invention can easily create orthoimages with a ground pixel size of 5 mm or less.

[0019] In the orthoimage creation method according to the present invention, the photographing device is an unmanned aerial vehicle or a model aircraft flying at an altitude of 20 meters or less above the ground.

[0020] In the orthoimage creation system according to the present invention, the photographing device is an unmanned aerial vehicle or a model aircraft flying at an altitude of 20 meters or less above the ground.

[0021] As a result, the orthoimage creation method and orthoimage creation system according to the present invention can easily create orthoimages with a ground pixel size of 5 mm or less over a relatively wide area.

[0022] In the orthoimage creation method of the present invention, the feature point is an anti-aircraft sign installed on the ground at the time of photographing in the photographing step, and the coordinate acquisition step is characterized in that the three-dimensional coordinates of the anti-aircraft sign are acquired by any one of a total station, a satellite-based positioning system, and a three-dimensional scanning device.

[0023] In the orthoimage creation system of the present invention, the feature point is an anti-aircraft sign installed on the ground at the time of photographing by the photographing device, and the coordinate storage means stores the three-dimensional coordinates of the anti-aircraft sign obtained by either a total station, a satellite-based positioning system, or a three-dimensional scanning device.

[0024] As a result, the orthoimage creation method and orthoimage creation system according to the present invention can easily create orthoimages that clearly show the condition of the road surface and the positions of planar elements around the road.

[0025] The ground model creation method according to the present invention is characterized by comprising a point cloud data acquisition step of acquiring three-dimensional coordinated point cloud data for each point in a specified area included in an orthoimage created by any of the above-mentioned orthoimage creation methods using laser light irradiated from a three-dimensional scanning device installed at a known point, and a ground model creation step of creating a ground model of the specified area based on the orthoimage and the point cloud data acquired by the point cloud data acquisition step.

[0026] The ground model creation system according to the present invention is characterized by comprising: a point cloud data storage means for storing point cloud data converted into three-dimensional coordinates for each point in a predetermined area included in an orthoimage created by any of the above-mentioned orthoimage creation systems using laser light irradiated from a three-dimensional scanning device installed at a known point; and a ground model creation means for creating a ground model of the predetermined area based on the orthoimage and the point cloud data stored in the point cloud data storage means.

[0027] As a result, the ground model creation method and ground model creation system according to the present invention can clearly detect the three-dimensional shape of a predetermined area included in an orthoimage, making it possible to clearly detect height information such as the height of unevenness on the road surface, steps around the road, and the height of manholes. [Effects of the Invention]

[0028] As described above, according to the present invention, it is possible to create an orthoimage that can clearly distinguish the condition of the road surface and the positions of planar elements around the road. It is also possible to clearly detect the three-dimensional shape of a specified area included in the orthoimage. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a diagram showing a schematic configuration of an orthoimage creation system according to an embodiment of the present invention. [Figure 2] FIG. 10 is a diagram showing a state in which a plurality of anti-aircraft signs are installed near both ends of a road when the road is photographed from above. [Figure 3] FIG. [Figure 4] FIG. 10 is a diagram illustrating a state in which an anti-aircraft marker is included in two captured images. [Figure 5] FIG. 1 is a diagram illustrating a method for creating an orthoimage in an orthoimage creation device. [Figure 6] FIG. 10 is a diagram showing a state in which an orthoimage is displayed on a display unit. [Figure 7] FIG. 1 is an enlarged view of a road surface on which cracks have formed. [Figure 8] FIG. 1 is an enlarged view of a road surface on which cracks have formed. [Figure 9] An enlarged view of the road surface where cracks have formed. [Figure 10] A close-up view of the road surface with a manhole. [Figure 11] FIG. 1 is a diagram illustrating the tape used to evaluate the detection of cracks formed on the road surface. [Figure 12]FIG. 12 is a diagram showing the state in which the tape of FIG. 11 is attached to the road surface. [Figure 13] FIG. 13 is a diagram showing an orthoimage of the road surface of FIG. 12. [Figure 14] FIG. 1 is a diagram illustrating a method for investigating the crack condition of a road surface. [Figure 15] FIG. 10 is a diagram showing a survey area in an orthoimage displayed on a display unit. [Figure 16] FIG. 16 is an enlarged view of part A within the survey area shown in FIG. 15. [Figure 17] FIG. 10 is a diagram showing the results of investigating the road surface conditions for each survey area in the entire survey area. [Figure 18] 10A and 10B are diagrams illustrating a method for investigating the positions of planar elements around a road. [Figure 19] FIG. 10 is a diagram showing a survey area in an orthoimage displayed on a display unit. [Figure 20] This is an ortho-CAD plan view of the orthoimage. [Figure 21] This is a diagram in which planar elements around the road have been traced on the ortho-CAD plan view of Figure 20. [Figure 22] This is a diagram illustrating planar elements of the entire survey area. [Figure 23] FIG. 1 is a diagram illustrating an investigation method for repairing the area around a manhole. [Figure 24] FIG. 10 is a diagram showing a survey area in an orthoimage displayed on a display unit. [Figure 25] FIG. 1 is a schematic diagram illustrating a longitudinal section plan. [Figure 26] FIG. 1 is a schematic diagram illustrating a cross-sectional plan. [Figure 27] FIG. 10 is a diagram showing the elevation of a predetermined position around a manhole displayed. [Figure 28] FIG. 10 is a diagram showing the adjustment heights of each position around the manhole. [Figure 29] FIG. 10 is a diagram illustrating a method for investigating the distance between specified points on the road surface. [Figure 30] FIG. 10 is a diagram showing a state in which the distance between specified points on the road surface is displayed. [Figure 31] FIG. 10 is a diagram illustrating a method for investigating the area of ​​a specified range on a road surface. [Figure 32] FIG. 10 is a diagram showing a state in which the area of ​​a specified range on the road surface is displayed. [Figure 33] FIG. 10 is a diagram showing a schematic configuration of an orthoimage creation system according to a modified example of the present invention. [Figure 34] FIG. 10 is a diagram illustrating a state in which an anti-aircraft marker is included in two captured images. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0031] An orthoimage creation system 1 (ground model creation system) according to an embodiment of the present invention includes a total station 2 installed at a known point (e.g., a reference point), a camera 3 as an imaging device, a 3D scanner 4 (three-dimensional scanning device) installed at the known point, and an orthoimage creation device 10 (ground model creation device) to which the total station 2, camera 3, and 3D scanner 4 are wirelessly connected.

[0032] The total station 2 emits distance measurement light toward each point on the road surface, receives the light reflected at each point, and acquires the three-dimensional coordinates of each point relative to a known point based on the number of times the light wave oscillates from emission to reception, and supplies the three-dimensional coordinates to the orthoimage creation system 10. In this embodiment, the total station 2 is used to acquire the three-dimensional coordinates of multiple anti-aircraft signs 6.

[0033] The camera 3 (photographing device) is operated by, for example, a road inspector to photograph the road surface and acquire photographed data, and supplies the photographed data to the orthoimage creation device 10.

[0034] The 3D scanner 4 emits laser light to acquire three-dimensional coordinated point cloud data (a set of elevations with planar position coordinates) of each point on the road surface, and supplies the point cloud data to the orthoimage creation system 10. The 3D scanner 4 emits line laser light, for example, vertically and horizontally, toward the measurement object (road surface), and measures the time it takes for the laser pulse to travel back and forth between the measurement point on the measurement object and the sensor, thereby determining the distance to the measurement point. In this embodiment, the 3D scanner 4 is used to acquire three-dimensional coordinates (point cloud data) of each point in an area including a repair location where road repair work is to be performed, at the time of repair work commencement. The point cloud data acquired by the 3D scanner 4 is data at positions spaced, for example, at intervals of 25 cm or less. In this embodiment, the 3D scanner 4 acquires point cloud data at positions spaced, for example, at intervals of 5 mm.

[0035] As shown in FIG. 1, the orthoimage creation device 10 is configured, for example, by a microcomputer, and includes a CPU, a ROM storing a program that controls the operation of the orthoimage creation device 10, and a RAM that temporarily stores data used when executing the program.

[0036] The orthoimage creation device 10 has a coordinate storage unit 11, a captured image storage unit 12, a point cloud data storage unit 13, an orthoimage creation unit 14, a ground model creation unit 15, and a display control unit 16. The orthoimage creation device 10 also has a display unit 5 such as a display screen.

[0037] The coordinate storage unit 11 stores three-dimensional coordinates of characteristic points such as a plurality of anti-aircraft signs 6 acquired by the total station 2 separately.

[0038] The captured image storage unit 12 stores a plurality of images of the road taken by a camera 3 held and operated by an inspector near the road. When taking images, the camera 3 is placed at an altitude of, for example, 20 meters or less above the ground, for example, 1 to 5 meters, and preferably 1 to 3 meters.

[0039] When a road is photographed by the camera 3, a plurality of anti-aircraft signs 6 are installed as a plurality of feature points, for example, near both ends of the road, as shown in FIG. 2. The plurality of anti-aircraft signs 6 are installed along the ends of the road (in the longitudinal direction of the road), for example, at intervals of 1 to 20 meters, preferably at intervals of 1 to 10 meters, and preferably at intervals of 1 to 5 meters. The plurality of anti-aircraft signs 6 are installed with consideration given to creating an orthoimage by connecting a plurality of photographed images taken by the camera 3. The anti-aircraft signs 6 are feature points for which three-dimensional coordinates are provided, and are used as assessment points. Note that when connecting a plurality of photographed images to create an orthoimage, feature points other than the anti-aircraft signs 6 that are included in the plurality of photographed images but for which three-dimensional coordinates are not provided may also be used.

[0040] As shown in FIG. 3, the anti-aircraft sign 6 is a square plate-like member. The anti-aircraft sign 6 has a pattern that clearly identifies its center position. The anti-aircraft sign 6 has an adhesive layer formed on its back surface, and is in the form of a sticker with a backing paper attached to cover the adhesive layer. By removing the backing paper and attaching the sign to the road, it can be easily fixed to the installation location. Therefore, when using the anti-aircraft sign 6, the backing paper covering the adhesive layer is removed and the back side of the anti-aircraft sign 6 is attached to the road surface. The anti-aircraft sign 6 of this embodiment is, for example, a 9 cm x 9 cm square, but the type, shape, size, pattern, etc. of the anti-aircraft sign 6 are not limited thereto.

[0041] In this embodiment, an inspector photographing a road takes photographs from a substantially constant height, moving from the outside of the road edge toward the center of the road, as shown in FIG. 4. At this time, the inspector photographs while moving along the road edge so as to capture the entire road surface without any gaps. As shown in FIG. 4, the multiple images taken by the camera 3 are taken so that at least one common anti-aircraft sign 6 is captured in two adjacent images. Note that while FIG. 4 illustrates a case in which the anti-aircraft sign 6 is included in all of the captured images, the multiple images taken by the camera 3 may be taken so that either the anti-aircraft sign 6 or a feature other than the anti-aircraft sign 6 is included in at least two of the captured images.

[0042] The point cloud data storage unit 13 separately stores point cloud data that has been converted into three-dimensional coordinates for each point in a predetermined region acquired by the 3D scanner 4. The predetermined region is at least a part of the region included in the orthoimage created by the orthoimage creation unit 14. In this embodiment, the predetermined region is the entire region included in the orthoimage created by the orthoimage creation unit 14.

[0043] The orthoimage creation unit 14 creates an orthoimage based on the three-dimensional coordinates of the anti-aircraft signs 6 stored in the coordinate memory unit 11 and the multiple captured images stored in the captured image memory unit 12. Specifically, the orthoimage creation unit 14 performs SfM (Structure from Motion) analysis or the like on the data for the multiple captured images to connect two adjacent captured images based on the common anti-aircraft signs 6 captured in those images, thereby creating an orthoimage. The ground pixel size of the orthoimage created by the orthoimage creation unit 14 is 5 millimeters or less. Note that if a vehicle is present on a road in the captured image used to create the orthoimage, it is possible to automatically recognize the vehicle (by automatic image recognition) and replace the area around the vehicle on the road with an image of the road without the vehicle in another captured image, thereby creating an orthoimage without the vehicle on the road.

[0044] The ground model creation unit 15 creates a ground model of a predetermined area included in the orthoimage based on the orthoimage created by the orthoimage creation unit 14 and the point cloud data stored in the point cloud data storage unit 13. Specifically, the ground model creation unit 15 creates a ground model by interpolating color information of the orthoimage created by the orthoimage creation unit 14 into the point cloud data stored in the point cloud data storage unit 13. In other words, the ground model is color-interpolated point cloud data. The predetermined area is at least a part of the area included in the orthoimage created by the orthoimage creation unit 14. Note that the ground model creation unit 15 of this embodiment creates a ground model of the entire area of ​​the orthoimage.

[0045] The display control unit 16 displays the orthoimage created by the orthoimage creation unit 14 on the display unit 5. The user can perform an operation to designate a predetermined position within the image displayed on the display unit 5 by pressing the display surface 5a of the display unit 5. For example, in a state where the orthoimage created by the orthoimage creation unit 14 is displayed on the display unit 5, the user can perform an operation to designate a predetermined position by pressing a predetermined position within the orthoimage displayed on the display surface 5a of the display unit 5.

[0046] (Creating orthoimages and ground models) A method for creating an orthoimage and a ground model in the orthoimage creation device 10 will be described with reference to FIG.

[0047] In step S1 (coordinate acquisition step), the total station 2 acquires three-dimensional coordinates, i.e., planar positions (latitude, longitude) and altitude (height), for multiple predetermined positions around the repair area where road repairs are to be performed, i.e., predetermined positions where multiple anti-aircraft signs 6 will be installed.

[0048] In step S2 (photographing step), the road is photographed by the camera 3. The camera 3 is operated, for example, by a road inspector near the road, and photographs the road while positioned at an altitude of 20 meters or less above the ground. When photographing is performed, a plurality of anti-aircraft markers 6 are installed in advance at a plurality of predetermined positions surveyed in step S1. Therefore, a plurality of photographed images are taken of the plurality of anti-aircraft markers 6 so that each anti-aircraft marker 6 is included in at least two photographed images.

[0049] In step S3 (point cloud data acquisition step), the 3D scanner 4 acquires point cloud data that is converted into three-dimensional coordinates for each point in the area where the photographed images are taken in step S2 and the orthoimage is to be created.

[0050] In step S4 (orthoimage creation step), an orthoimage is created based on the three-dimensional coordinates acquired in step S1 and the multiple captured images taken in step S2.

[0051] In step S5 (ground surface model creation step), a ground surface model is created based on the orthoimage created in step S4 and the point cloud data acquired in step S3.

[0052] In step S6 (display step), the orthoimage created in step S4 or the ground model created in step S5 is displayed.

[0053] 6 shows the orthoimage created in step S4 displayed on the display unit 5. In this embodiment, the ground pixel size of the orthoimage is 5 mm or less.

[0054] 7 to 9 are enlarged views of a road surface on which cracks have formed. Fig. 10 is an enlarged view of a road surface on which a manhole is located. In this way, in the orthoimage created by the orthoimage creation device 10 of this embodiment, it is possible to clearly identify cracks formed on the road surface, and also to clearly identify the type of manhole based on the letters and symbols written on the manhole cover.

[0055] In addition, when investigating crack conditions on road surfaces, conventionally, when road conditions are investigated using a dedicated road surface property measurement vehicle, it is possible to detect cracks of about 1 mm width formed on the road surface. Therefore, an evaluation was conducted to determine whether the orthoimages created by the present invention can detect cracks of about 1 mm width formed on the road surface in the same way as a dedicated road surface property measurement vehicle.

[0056] For the above evaluation, 1mm-, 2mm-, and 3mm-wide tapes were used and attached to the road surface to simulate cracks of 1mm, 2mm, and 3mm in width, as shown in Figures 11 and 12. After that, the road with the simulated cracks formed was photographed from above by a UAV flying at an altitude of 20 meters or less above the ground, and an orthoimage was created.

[0057] Figure 13 shows an orthoimage of a road with simulated cracks formed on it. It was found that the orthoimage created by the present invention can detect simulated cracks of 1 mm, 2 mm, and 3 mm width formed on the road surface. Therefore, the orthoimage created by the present invention can detect cracks of about 1 mm width formed on the road surface. It is considered that the same can be achieved when an orthoimage is created by photographing a road with a camera 3 placed at an altitude of 20 meters or less above the ground.

[0058] As shown in Figures 6 to 13, in the orthoimages created in step S4, it is possible to clearly detect, for example, the positions of road edges, the positions of cracks on the road surface, the positions of planar elements around the road, and the positions of manholes.

[0059] However, in the orthoimage created in step S4, it may be impossible to clearly detect three-dimensional shapes such as unevenness on the road surface.

[0060] Therefore, in this embodiment, when it is necessary to clearly detect the three-dimensional shape of the road surface in a specified area contained in the orthoimage created in step S4, the coordinate system of the orthoimage and the coordinate system of the point cloud data acquired in step S3 are made identical and pasted together to create a ground model of the specified area.

[0061] Specifically, the color information for each point in the orthoimage is interpolated into the point cloud data at the position corresponding to that point. In the color-interpolated point cloud data, each point then has x-, y-, and z-coordinates as well as color information, making it possible to clearly detect three-dimensional shapes such as unevenness on the road surface, which was previously difficult to detect clearly in the orthoimage.

[0062] In this way, in this embodiment, when it is necessary to clearly detect the planar positions of, for example, the positions of cracks formed on the surface of a road, the positions of unevenness on the road surface, the positions of manholes, etc., it is possible to clearly detect them by enlarging the orthoimage.

[0063] On the other hand, when height information such as the height of unevenness on the road surface or the height of a manhole needs to be detected clearly, it is possible to perform the detection clearly based on the ground model.

[0064] That is, the ground model created in step S5 has appropriate x-, y-, and z-coordinates for each point included in the orthoimage, and based on the ground model, for example, the cross-sectional shape of an arbitrary position on the ground model can be displayed on the display unit 5, thereby making it possible to display the three-dimensional shape of the ground included in the orthoimage (for example, unevenness of the road surface, cracks on the road surface, etc.). Therefore, the three-dimensional shape of the ground included in the orthoimage can be clearly detected.

[0065] (Road survey method using orthoimages) The orthoimages created by the orthoimage creation device 10 as described above are used for various surveys that are carried out when road repairs are carried out.

[0066] In this embodiment, using orthoimages created by the orthoimage creation device 10, we will explain a road survey method when conducting (1) an investigation into the condition of cracks on the road surface, (2) an investigation into the location of planar elements around the road including areas where repairs will be performed, (3) an investigation for repairing the area around a manhole, (4) an investigation into the distance between two specified points on the road surface, and (5) an investigation into the area of ​​a specified range on the road surface.

[0067] (Road Survey Method 1) The method for investigating the crack condition on the road surface will be explained with reference to FIG.

[0068] In the investigation of the crack condition of the road surface, the areas where cracks have formed on the road surface, including the repair areas where road repairs will be carried out, and the crack rate and patching rate in those areas are investigated.

[0069] After the orthoimage is displayed in steps S1 to S4 described above, in step S7, the crack condition of the road surface is investigated based on the orthoimage displayed on the display unit 5. Specifically, the investigation area of ​​the road displayed on the display unit 5 is divided into a plurality of investigation ranges, and the crack rate and patching rate of the road surface are investigated for each investigation range.

[0070] 15 illustrates the survey area in the orthoimage displayed on the display unit 5. In this embodiment, the survey area is divided into survey ranges of 50 cm x 50 cm, and for each survey range, a survey of the crack rate and a survey of the patching rate are conducted as a survey of the crack condition. In this embodiment, the survey of the crack rate involves a survey of the crack amount (quantity of cracks) for each survey range.

[0071] FIG. 16 is an enlarged view of portion A within the survey area shown in FIG. 15, showing the state of the area divided into multiple survey ranges. For each survey range, FIG. 16 distinguishes between the following states: no cracks and a patching rate of 25% or less, a linear crack state (a state with one crack), a planar crack state (a state with two or more cracks), a patching rate of 25 to 75%, and a patching rate of 75% or more. While FIG. 16 distinguishes the road surface state for each survey range using different patterns, the road surface state for each survey range may also be displayed using different colors.

[0072] In step S8 (road condition display step), the results of investigating the crack condition of the road surface for each investigation range in the entire investigation area are displayed on the display unit 5, as shown in Fig. 17. In Fig. 17, the investigation ranges for linear cracks, planar cracks, patching rates of 25 to 75%, and patching rates of 75% or more may be displayed, for example, in different colors. Furthermore, the investigation ranges for linear cracks and planar cracks may be displayed, for example, in different colors, from the investigation ranges for patching rates of 25 to 75% and patching rates of 75% or more.

[0073] (Road Survey Method 2) The method for investigating the positions of planar elements around a road will be described with reference to FIG.

[0074] When investigating the locations of planar elements around the road, the locations of planar elements including the edges of the road, including repair areas where road repairs will be performed, road deformations, dividing lines such as white painted areas on the road surface indicating lanes, and lines indicating the locations of manholes, etc. are investigated.

[0075] After the orthoimage is created by steps S1 to S4 described above, in step S9 (planar element mapping step), tracing of planar elements around the road is performed manually or automatically (auto-trace processing) based on the orthoimage displayed on the display unit 5. Specifically, tracing of planar elements is performed on the road displayed on the display unit 5, including, for example, road edges, road deformations, division lines such as white painted parts on the road surface that indicate lanes, and lines indicating the positions of manholes, etc.

[0076] Figure 19 illustrates the survey area in the orthoimage displayed on the display unit 5. Figure 20 is an ortho-CAD plan view of the orthoimage shown in Figure 6, and Figure 21 shows a diagram in which planar elements around the road have been traced on the ortho-CAD plan view of Figure 20. An ortho-CAD plan view is a plan view created by converting an orthoimage into 2D CAD. Therefore, in Figure 21, lines indicating the positions of planar elements around the road have been added to the ortho-CAD plan view corresponding to the orthoimage of Figure 20.

[0077] In step S10, as shown in FIG. 22, a tracing process is performed on planar elements around roads in the entire survey range, and the planar elements are plotted and displayed on the display unit 5.

[0078] (Road Survey Method 3) The investigation method for repairing the area around the manhole will be explained based on Figure 23.

[0079] In a survey to repair the area around a manhole, the height (adjustment height) to be adjusted so that the elevation of the area around the manhole matches the elevation of the repair plan surface is investigated. Therefore, the adjustment height of the area around the manhole is the difference in elevation between the elevation of the area around the manhole at the time of repair work and the elevation of the repair plan surface. The adjustment height of the area around the manhole is investigated by investigating the difference in elevation between two locations, upstream and downstream in the longitudinal direction of the manhole, and the difference in elevation between two locations, upstream and downstream in the transverse direction of the manhole.

[0080] Fig. 24 illustrates a survey area in the orthoimage displayed on the display unit 5. The survey area in Fig. 24 includes one manhole and the surrounding area of ​​the manhole.

[0081] After the orthoimage is displayed in steps S1 to S4 described above, longitudinal and cross-sectional planning is performed in step S11, and plan data showing a repair plan for repairing a road is acquired.

[0082] The repair plan includes longitudinal and transverse plans, and after longitudinal planning along the longitudinal direction of the road is performed, transverse planning along the transverse direction at multiple locations on the road is performed to obtain a repair plan surface to be used when repairing. Therefore, the repair plan surface includes plan surface data indicating the longitudinal plan surface and plan surface data indicating multiple transverse plan surfaces.

[0083] A longitudinal plan includes a plan for the elevation of each point on a line along the longitudinal direction of the road in the center of the road. For example, Figure 25 shows a longitudinal plan surface for the elevation of each point on a line along the center of the road. In Figure 25, a repair area requiring a repair plan is located between an unrepaired area on the left side and an unrepaired area on the right side. The repair area in Figure 25 is shown with elevation changes based on point cloud data and a longitudinal plan surface.

[0084] The longitudinal section plan shown in Figure 25 is obtained by connecting the elevations at each position on a line along the center of the road, after the elevations at each position on the line along the center of the road are planned taking into consideration the flatness of the road, etc. The positions on the line along the center of the road are, for example, every 10 m or every 20 m.

[0085] In longitudinal planning, elevations at each position on a line along the center of the road are planned, followed by cross-sectional planning. Cross-sectional planning is a plan for elevations at each point on a line along the cross-sectional direction of the road at each position on the line along the center of the road. For example, Figure 26 shows a cross-sectional planning surface for elevations at each point on a line along the cross-sectional direction of the road at point a in Figure 25. In Figure 26, a repair location requiring a repair plan is located between the left edge and the right edge of the road. The cross-sectional planning surface is also shown at the repair location, along with elevation changes based on point cloud data. Figure 26 illustrates the slope of the road for easy understanding.

[0086] The cross-section planning surface is obtained by planning for each position on the line along the center of the road shown in Figure 25, taking into consideration the gradient of the slope that slopes downward from the elevation of the center of the road toward both ends of the road. For example, when planning a cross-section of a road, it is generally designed so that the slope slopes downward at a predetermined gradient from the center of the road toward the ends of the road.

[0087] For example, in the cross-sectional plan of FIG. 26 , the elevation of the road center at point a on the longitudinal plan of FIG. 25 decreases to point a1 along a slope that slopes downward at a predetermined gradient toward both ends of the road. The elevation then decreases along connecting surfaces that connect point a1 to the left and right ends of the road. Therefore, when repairs are made based on the cross-sectional plan, the surface layer of the asphalt pavement formed at the repaired area is connected to the concrete sections at the left and right ends of the road without any steps. Note that the cross-sectional plan of FIG. 26 is an example of a cross-sectional plan, and cross-sectional planning methods are not limited to this. Therefore, the cross-sectional plan may be designed, for example, so that slopes that slope downward at different gradients from the road center toward the road edges are connected.

[0088] By connecting the cross-sectional plan surfaces at each position on the line along the center of the road obtained as described above in the longitudinal direction, a repair plan surface for repairing the road surface is obtained.

[0089] In step S12 (point cloud data acquisition step), point cloud data of each point on the road surface is acquired by the 3D scanner 4. The point cloud data acquired by the 3D scanner 4 is converted into a three-dimensional TIN model (irregular triangular network), which is a collection of triangular planes connected at vertices, and data corresponding to the latitude, longitude, and altitude of each point on the road surface can be derived. Even if point cloud data of each point in the survey area has not been acquired by the 3D scanner 4, data corresponding to the latitude, longitude, and altitude of each point can be derived.

[0090] In step S13 (ground surface model creation step), a ground surface model is created based on the orthoimage created in step S4 and the point cloud data of each point in the survey area acquired in step S12. The ground surface model has appropriate x-, y-, and z-coordinates of each point in the survey area.

[0091] In step S14 (altitude difference derivation step), by pressing and specifying a predetermined position around the manhole based on the ground model (orthoimage) displayed on the display surface 5a of the display unit 5, the planar position (latitude, longitude) of the predetermined position is displayed, as shown in Fig. 27. Therefore, by changing the position specified around the manhole in the orthoimage displayed on the display surface 5a of the display unit 5, two planar positions, one on the upstream side and one on the downstream side in the longitudinal direction of the manhole, and two planar positions, one on the upstream side and one on the downstream side in the transverse direction of the manhole, are detected.

[0092] The elevation of each position around the manhole at the time repair work begins is derived based on the detected planar position of each position around the manhole, and the elevation of that planar position is derived based on the point cloud data acquired by the 3D scanner 4. In this embodiment, using the orthoimage and the point cloud data acquired by the 3D scanner 4, the elevation of all planar positions in the orthoimage can be derived based on the point cloud data acquired by the 3D scanner 4. The elevation of each position on the repair plan surface is extracted from the plan surface data indicating the repair plan surface acquired in step S9.

[0093] Next, the elevation difference between the elevation of each location around the manhole at the time of repair work commencement and the elevation of each location on the repair plan is calculated as the adjustment height. Therefore, two adjustment heights, one upstream and one downstream of the manhole in the longitudinal direction, and two adjustment heights, one upstream and one downstream of the manhole in the transverse direction, are calculated. Figure 28 shows that the adjustment heights for each location around the manhole are a1 cm, a2 cm, a3 cm, and a4 cm, respectively. Therefore, a1 cm is the adjustment height on the upstream side of the manhole in the transverse direction, a2 cm is the adjustment height on the upstream side of the manhole in the longitudinal direction, a3 cm is the adjustment height on the downstream side of the manhole in the transverse direction, and a4 cm is the adjustment height on the downstream side of the manhole in the longitudinal direction.

[0094] (Road Survey Method 4) A method for investigating the distance between two specified points on the road surface will be described with reference to FIG.

[0095] In investigating the distance between two specified points on the road surface, when various distances are required for road repair, the distances are investigated based on the orthoimage displayed on the display unit 5. Distances required for road repair include, for example, the length of the road repair section, the width of the road, and the length of a specified area on the road surface.

[0096] In step S101 (point cloud data acquisition step), point cloud data of each point on the road surface around the repair location where road repair is to be performed is acquired by the 3D scanner 4. The point cloud data acquired by the 3D scanner 4 is converted into a three-dimensional TIN model (irregular triangular network), which is a collection of triangular planes connected at vertices, and data corresponding to the latitude, longitude, and altitude of each point on the road surface can be derived. Even if point cloud data of each point in the survey area has not been acquired by the 3D scanner 4, data corresponding to the latitude, longitude, and altitude of each point can be derived.

[0097] In step S102 (coordinate acquisition step), based on the point cloud data acquired in step S101, three-dimensional coordinates, i.e., planar positions (latitude, longitude) and altitudes (height), are acquired for a plurality of predetermined positions around the repair location where road repair is to be performed, i.e., predetermined positions where a plurality of anti-aircraft signs 6 will be installed. The three-dimensional coordinates of the plurality of predetermined positions may be acquired by a total station 2.

[0098] In step S103 (photographing step), the road is photographed by the camera 3 from near the road. When photographing is performed, a plurality of anti-aircraft markers 6 are installed in advance at a plurality of predetermined positions whose three-dimensional coordinates have been acquired in step S102. Therefore, a plurality of photographed images are taken of the plurality of anti-aircraft markers 6 so that each anti-aircraft marker 6 is included in at least two photographed images.

[0099] In step S104 (orthoimage creation step), an orthoimage is created based on the three-dimensional coordinates acquired in step S102 and the multiple captured images taken in step S103. At this time, the orthoimage created in step S104 is associated with the point cloud data acquired in step S101. That is, each point in the orthoimage is associated with the three-dimensional coordinates of the point cloud data, and each point on the orthoimage corresponds to a planar position (latitude, longitude) and an altitude (height).

[0100] In step S105 (display step), the orthoimage is displayed on the display unit 5 as shown in Fig. 6. In step S106 (distance display step), by pressing and specifying two designated points on the road surface on the orthoimage displayed on the display surface 5a of the display unit 5, the distance between the designated points is displayed. For example, as shown in Fig. 30, when two designated points A1 and A2 at an intersection are specified, the distance between the designated points A1 and A2 is displayed. Therefore, even if measurements of various distances required for road repair are not performed when photographing the road with the camera 3 from near the road in step S103 (photographing step), the distances between various designated points within the range of the orthoimage can be detected by changing the positions of the two designated points on the road surface in the orthoimage displayed on the display surface 5a of the display unit 5.

[0101] (Road Survey Method 5) The method for investigating the area of ​​a specified range on the road surface will be explained with reference to FIG.

[0102] In the survey of the area of ​​a specified range on the road surface, when the areas of various regions are required for road repair, the areas of those regions are surveyed based on the orthoimage displayed on the display unit 5. The areas required for road repair include, for example, the area of ​​the road repair portion.

[0103] In step S101 (point cloud data acquisition step), point cloud data of each point on the road surface around the repair location where road repair is to be performed is acquired by the 3D scanner 4. The point cloud data acquired by the 3D scanner 4 is converted into a three-dimensional TIN model (irregular triangular network), which is a collection of triangular planes connected at vertices, and data corresponding to the latitude, longitude, and altitude of each point on the road surface can be derived. Even if point cloud data of each point in the survey area has not been acquired by the 3D scanner 4, data corresponding to the latitude, longitude, and altitude of each point can be derived.

[0104] In step S102 (coordinate acquisition step), based on the point cloud data acquired in step S101, three-dimensional coordinates, i.e., planar positions (latitude, longitude) and altitudes (height), are acquired for a plurality of predetermined positions around the repair location where road repair is to be performed, i.e., predetermined positions where a plurality of anti-aircraft signs 6 will be installed. The three-dimensional coordinates of the plurality of predetermined positions may be acquired by a total station 2.

[0105] In step S103 (photographing step), the road is photographed by the camera 3 from near the road. When photographing is performed, a plurality of anti-aircraft markers 6 are installed in advance at a plurality of predetermined positions whose three-dimensional coordinates have been acquired in step S102. Therefore, a plurality of photographed images are taken of the plurality of anti-aircraft markers 6 so that each anti-aircraft marker 6 is included in at least two photographed images.

[0106] In step S104 (orthoimage creation step), an orthoimage is created based on the three-dimensional coordinates acquired in step S102 and the multiple captured images taken in step S103. At this time, the orthoimage created in step S104 is associated with the point cloud data acquired in step S101. That is, each point in the orthoimage is associated with the three-dimensional coordinates of the point cloud data, and each point on the orthoimage corresponds to a planar position (latitude, longitude) and an altitude (height).

[0107] In step S105 (display step), the orthoimage is displayed on the display unit 5 as shown in Fig. 6. In step S108 (area display step), by specifying a specified range of the road surface on the orthoimage displayed on the display surface 5a of the display unit 5, the area of ​​the specified range is displayed as shown in Fig. 32. For example, as shown in Fig. 32, when a specified range (shaded area) indicating the upper part of an intersection is specified, the area of ​​the specified range is displayed. Therefore, even if measurements of various areas required for road repair are not performed when photographing the road with the camera 3 from near the road in step S103 (photographing step), the areas of various regions within the range of the orthoimage can be detected by changing the position of the specified range of the road surface in the orthoimage displayed on the display surface 5a of the display unit 5.

[0108] The orthoimage creation method of this embodiment includes a coordinate acquisition step of acquiring three-dimensional coordinates for a plurality of feature points, a photographing step of capturing a plurality of photographed images using a camera 3 (photography device) so that each feature point is included in at least two photographed images, and an orthoimage creation step of creating an orthoimage with a ground pixel dimension of 5 millimeters or less based on the three-dimensional coordinates of each feature point acquired in the coordinate acquisition step and the plurality of photographed images captured in the photographing step.

[0109] The orthoimage creation system 1 of this embodiment includes a coordinate memory unit 11 (coordinate memory means) that stores three-dimensional coordinates for multiple feature points, a captured image memory unit 12 (captured image memory means) that stores multiple captured images of multiple feature points captured by a camera 3 (photography device) so that each feature point is included in at least two captured images, and an orthoimage creation unit 14 (orthoimage creation means) that creates an orthoimage with a ground pixel dimension of 5 millimeters or less based on the three-dimensional coordinates of each feature point stored in the coordinate memory unit 11 and the multiple captured images stored in the captured image memory unit 12.

[0110] As a result, the orthoimage creation method and orthoimage creation system 1 of this embodiment create orthoimages with ground pixel dimensions of 5 millimeters or less, making it possible to create orthoimages that clearly show the condition of the road surface and the positions of planar elements around the road.The orthoimages created by this invention make it possible to clearly identify areas where cracks have occurred on the road and areas where patching has occurred.Therefore, since there is no need to run a dedicated road surface property measurement vehicle to investigate the condition of cracks on the road surface, it is possible to investigate road conditions regardless of road width.

[0111] Furthermore, in the orthoimage created in this embodiment, the positions of planar elements including road edges and lane markings can be clearly identified. Therefore, since it is not necessary to conduct surveys at a large number of planar positions in order to plot planar elements including road edges and lane markings, it is possible to easily plot planar elements based on the orthoimage.

[0112] Furthermore, the orthoimage created in this embodiment can detect the vertical and horizontal plane positions of the area surrounding the manhole. Therefore, after identifying the vertical and horizontal plane positions of the area surrounding the manhole, the elevation of each plane position can be extracted from the point cloud data acquired by the 3D scanning device. Therefore, there is no need to create road vertical and horizontal sections for each manhole in order to detect the elevation of each vertical and horizontal plane position of the area surrounding the manhole. Therefore, the manhole adjustment height can be easily detected.

[0113] In the orthoimage creation method of this embodiment, the camera 3 (photographing device) is a photographing device located at an altitude of 20 meters or less above the ground.

[0114] In the orthoimage creation system 1 of this embodiment, the camera 3 (photographing device) is a photographing device located at an altitude of 20 meters or less above the ground.

[0115] As a result, the orthoimage creation method and orthoimage creation system 1 of this embodiment can easily create orthoimages with a ground pixel size of 5 mm or less.

[0116] In the orthoimage creation method of this embodiment, the feature point is an anti-aircraft sign 6 installed on the ground at the time of photographing in the photographing step, and in the coordinate acquisition step, the three-dimensional coordinates of the anti-aircraft sign 6 are acquired by the total station 2.

[0117] In the orthoimage creation system 1 of this embodiment, the feature point is an anti-aircraft sign 6 installed on the ground at the time of photographing by the camera 3 (photographing device), and the coordinate memory unit 11 (coordinate memory means) stores the three-dimensional coordinates of the anti-aircraft sign 6 acquired by the total station 2.

[0118] As a result, the orthoimage creation method and orthoimage creation system 1 of this embodiment can easily create an orthoimage in which the state of the road surface and the positions of planar elements around the road can be clearly determined.

[0119] The ground model creation method of this embodiment includes a point cloud data acquisition step of acquiring three-dimensional coordinated point cloud data for each point in a specified area included in an orthoimage created by any of the above-mentioned orthoimage creation methods using laser light irradiated from a 3D scanner 3 (three-dimensional scanning device) installed at a known point, and a ground model creation step of creating a ground model of the specified area based on the orthoimage created by the orthoimage creation method and the point cloud data acquired by the point cloud data acquisition step.

[0120] The ground model creation system of this embodiment includes a point cloud data storage unit 13 (point cloud data storage means) that stores point cloud data converted into three-dimensional coordinates for each point in a specified area included in an orthoimage created by any of the above-mentioned orthoimage creation systems using laser light irradiated from a 3D scanner 3 (three-dimensional scanning device) installed at a known point, and a ground model creation unit 15 (ground model creation means) that creates a ground model of the specified area based on the orthoimage and the point cloud data stored in the point cloud data storage unit 13.

[0121] As a result, the ground model creation method and ground model creation system of this embodiment can clearly detect the 3D shape of a predetermined area included in an orthoimage, making it possible to clearly detect height information such as the height of unevenness on the road surface, steps around the road, and the height of manholes.

[0122] The above describes an embodiment of the present invention, but the specific configuration of each part is not limited to the above-described embodiment, and various modifications are possible within the scope of the spirit of the present invention.

[0123] In the above embodiment, an inspector near the road operates the camera 3 to photograph the road surface, but an unmanned aerial vehicle (UAV103) flying above the road may have a photographing device, photograph the road surface from above, acquire photographic data, and supply the photographic data to the orthoimage creation device 10.

[0124] In this case, as shown in Figure 33, the orthoimage creation system 1 (ground model creation system) of this modified example may include, for example, a total station 2 installed at a known point (for example, a reference point), a UAV103 (Unmanned Aerial Vehicle) which is an unmanned aerial vehicle used as an imaging device, a 3D scanner 4 (three-dimensional scanning device) installed at the known point, and an orthoimage creation device 10 (ground model creation device) to which the total station 2, UAV103, and 3D scanner 4 are wirelessly connected.

[0125] The UAV 103 flies above the road at a substantially constant altitude and photographs the road from above. When photographing, the UAV 103 flies at an altitude of 20 meters or less above the ground, for example, at an altitude of 5 to 20 meters, and preferably at an altitude of 5 to 15 meters.

[0126] When photographing a road from the sky using a UAV 103, a plurality of anti-aircraft signs 6 are installed near both ends of the road as a plurality of feature points. The multiple anti-aircraft signs 6 are installed at intervals of, for example, 5 to 15 meters along the edges of the road (in the longitudinal direction of the road). The multiple anti-aircraft signs 6 are installed with consideration given to the creation of an orthoimage by connecting multiple images photographed from the sky.

[0127] As shown in Fig. 34, the multiple images captured by the UAV 103 are captured so that each anti-aircraft sign 6 is included in at least two of the captured images. Therefore, at least one common anti-aircraft sign 6 is captured in two adjacent captured images. Note that Fig. 34 illustrates a case where the anti-aircraft sign 6 is included in all of the captured images, but the multiple images captured by the UAV 103 may be captured so that either the anti-aircraft sign 6 or a feature point other than the anti-aircraft sign 6 is included in at least two of the captured images.

[0128] In addition, the orthoimage creation system (ground model creation system) of the present invention has a camera and a UAV as photographing devices, and may create an orthoimage or ground model by using a combination of images of the road surface taken by an inspector near the road operating the camera and images of the road surface taken from above by a UAV flying above the road.

[0129] In the above embodiment, an orthoimage is created based on images of the road captured by a camera 3 from a substantially constant height. In the above variant, an orthoimage is created based on images captured from above the road by a UAV 103 flying at a substantially constant altitude. However, the present invention also includes systems that create orthoimages based on images of the road captured by a camera 3 from different heights, or systems that create orthoimages based on images captured from above the road by a UAV 103 flying at different altitudes less than 20 meters above the ground. In the above embodiment, the three-dimensional coordinates of the anti-aircraft signs 6 installed around the road are acquired by a total station 2. However, the three-dimensional coordinates of the anti-aircraft signs 6 installed around the road may also be acquired by a GNSS (Global Navigation Satellite System), a satellite-based positioning system such as GPS. The three-dimensional coordinates of the anti-aircraft signs 6 installed around the road may also be acquired by scanning with a 3D scanner 4. In the above embodiment, the anti-aircraft markers 6 have a pattern that clearly identifies the central position used as the assessment point. However, the anti-aircraft markers 6 may have a pattern that identifies a position other than the central position, and the position other than the central position may be used as the assessment point. Furthermore, in the above embodiment, multiple anti-aircraft markers 6 are installed along the edge of the road (the longitudinal direction of the road) at intervals of, for example, 1 to 3 meters. In the above modification, multiple anti-aircraft markers 6 are installed at intervals of, for example, 5 to 15 meters. However, the arrangement of multiple anti-aircraft markers 6 is arbitrary. Therefore, multiple anti-aircraft markers 6 may be installed along the width direction of the road at intervals of, for example, 1 meter or less. Furthermore, in step S1 (coordinate acquisition step), three-dimensional coordinates are acquired by the total station 2 for predetermined positions where multiple anti-aircraft markers 6 are installed. However, if three-dimensional coordinates for the predetermined positions have already been acquired, those three-dimensional coordinates may be acquired instead. Furthermore, in the above embodiment, plate-shaped anti-aircraft markers 6 are installed on the road surface. However, instead of using plate-shaped anti-aircraft markers 6, a pattern similar to the anti-aircraft markers 6 may be formed on the road surface using any material, such as paint. For example, a pattern similar to the anti-aircraft sign 6 may be formed on the asphalt surface of a road by spraying a paint of a different color than the asphalt surface to form a pattern of the same shape as the white part of the anti-aircraft sign 6 in Figure 3.When anti-aircraft signs are formed on the road surface using any material such as paint, the type, shape, size, pattern, etc. of the anti-aircraft sign are also arbitrary.

[0130] In the above-described modified example, the road was photographed by an unmanned aerial vehicle (including a camera) flying at an altitude of 20 meters or less above the ground, but the road may also be photographed by a model aircraft (including a camera) flying at an altitude of 20 meters or less above the ground. In the present invention, an unmanned aerial vehicle is an airplane, rotorcraft, airship, or the like that cannot carry a person and can fly by remote control or automatic piloting, such as a drone (multicopter), radio-controlled aircraft, etc. Furthermore, a model aircraft is, for example, a multicopter, radio-controlled aircraft, etc., that weighs less than 200 grams, which is the total weight of the aircraft body and the battery weight.

[0131] In the above embodiment and modified example, an anti-aircraft sign 6 installed on the ground at the time of shooting is used as a feature point for connecting multiple captured images, and the three-dimensional coordinates of the anti-aircraft sign 6 are each acquired by the total station 2, but if a specific point in an image captured by the camera 3 (UAV 103) is used as a feature point for connecting multiple captured images, and three-dimensional coordinated point cloud data for each point in the captured image including the specific point has already been acquired by scanning with the 3D scanner 4, the three-dimensional coordinates of the specific point may be acquired from that point cloud data.

[0132] In the above embodiments, examples of methods for creating an orthoimage and a ground model have been described, but the order of each step may be changed as appropriate. In Figures 5, 14, 18, and 23, the order of steps S1, S2, and S3 may be changed. For example, it is possible to capture an image after acquiring the three-dimensional coordinates of the anti-aircraft sign 6, and it is also possible to acquire the three-dimensional coordinates of the anti-aircraft sign 6 after capturing the image. Alternatively, capturing an image and acquiring the three-dimensional coordinates of the anti-aircraft sign 6 may be performed simultaneously. In Figures 5, 14, 18, and 23, the order of steps S3 and S4 may be reversed. For example, it is possible to create an orthoimage after acquiring point cloud data, and it is also possible to acquire the point cloud data after creating the orthoimage. Alternatively, it is possible to create an orthoimage and acquire the point cloud data simultaneously.

[0133] In the above embodiment, examples of a method for creating an orthoimage and a method for creating a ground model have been described. However, in FIGS. 29 and 31, the order of steps S102 and S103 may be reversed. Therefore, it is possible to capture an image after acquiring the three-dimensional coordinates of the anti-aircraft sign 6, and it is also possible to acquire the three-dimensional coordinates of the anti-aircraft sign 6 after acquiring the image. Alternatively, capturing an image and acquiring the three-dimensional coordinates of the anti-aircraft sign 6 may be performed simultaneously. Also, in FIGS. 29 and 31, the order of steps S101 and S103 may be reversed. Therefore, it is possible to acquire point cloud data of an area including a plurality of anti-aircraft signs 6 before capturing an image of the area including a plurality of anti-aircraft signs 6. However, it is also possible to acquire point cloud data of an area including a plurality of anti-aircraft signs 6 after capturing an image of the area including a plurality of anti-aircraft signs 6.

[0134] In the above embodiment, the following surveys are conducted using orthoimages created by the orthoimage creation device 10: a survey of the crack condition on the road surface, a survey of the position of planar elements around the road, a survey to repair the area around a manhole, a survey of the distance between two specified points on the road surface, and a survey of the area of ​​a specified range on the road surface. However, the orthoimages created by the orthoimage creation device 10 may be used for other surveys. [Explanation of symbols]

[0135] 1 Orthoimage creation system (ground model creation system) 2. Total Station 3 Camera (photography device) 4. 3D scanner (3D scanning device) 5 Display section 6 Anti-aircraft markings 10 Ortho image creation device (ground model creation device) 11 Coordinate storage unit (coordinate storage means) 12 Photographed image storage unit (photographed image storage means) 13 Point cloud data storage unit (point cloud data storage means) 14 Orthoimage creation unit (orthoimage creation means) 15 Ground model creation unit (ground model creation means) 16 Display control unit 103 UAV (unmanned aerial vehicle)

Claims

1. a coordinate acquisition step of acquiring three-dimensional coordinates of a plurality of feature points; a photographing step of photographing a plurality of images by an imaging device so that each of the plurality of feature points is included in at least two of the photographed images; an orthoimage creation step of creating an orthoimage with a ground pixel size of 5 millimeters or less based on the three-dimensional coordinates of each feature point acquired in the coordinate acquisition step and the plurality of photographed images acquired in the photographing step.

2. 3. The orthoimage creation method according to claim 2, wherein the imaging device is an imaging device located at an altitude of 20 meters or less above the ground.

3. 3. The orthoimage creation method according to claim 2, wherein the photographing device is an unmanned aerial vehicle or a model aircraft flying at an altitude of 20 meters or less above the ground.

4. the feature point is an anti-aircraft sign installed on the ground at the time of photographing in the photographing step, An orthoimage creation method according to any one of claims 1 to 3, wherein in the coordinate acquisition step, the three-dimensional coordinates of the anti-aircraft sign are acquired by either a total station, a satellite-based positioning system, or a three-dimensional scanning device.

5. A point cloud data acquisition step of acquiring three-dimensional coordinated point cloud data for each point in a predetermined area included in an orthoimage created by any one of the orthoimage creation methods of claims 1 to 4 using laser light irradiated from a three-dimensional scanning device installed at a known point; A ground model creation method comprising a ground model creation step of creating a ground model of the specified area based on the orthoimage and the point cloud data acquired in the point cloud data acquisition step.

6. a coordinate storage means for storing three-dimensional coordinates of a plurality of feature points; a photographed image storage means for storing a plurality of photographed images photographed by a photographing device such that each of the plurality of feature points is included in at least two of the photographed images; an orthoimage creation system comprising: an orthoimage creation means for creating an orthoimage with a ground pixel size of 5 millimeters or less based on the three-dimensional coordinates of each feature point stored in the coordinate storage means and the plurality of photographed images stored in the photographed image storage means.

7. The orthoimage creation system according to claim 6, wherein the imaging device is an imaging device located at an altitude of 20 meters or less above the ground.

8. The orthoimage creation method according to claim 7, wherein the photographing device is an unmanned aerial vehicle or a model aircraft flying at an altitude of 20 meters or less above the ground.

9. the feature point is an anti-aircraft marking installed on the ground at the time of photographing by the photographing device, The coordinate storage means stores three-dimensional coordinates of the anti-aircraft sign acquired by either a total station, a satellite-based positioning system, or a three-dimensional scanning device. An orthoimage creation system as described in any one of claims 6 to 8.

10. A point cloud data storage means for storing point cloud data converted into three-dimensional coordinates for each point in a predetermined area included in an orthoimage created by the orthoimage creation system of any one of claims 6 to 9 using laser light irradiated from a three-dimensional scanning device installed at a known point; a ground model creation system comprising: a ground model creation means for creating a ground model of the specified area based on the orthoimage and the point cloud data stored in the point cloud data storage means.

Images