Underground data management device, method, and program

Abstract

Even when the survey area spans long distances, the system accurately aligns underground data acquired along multiple survey lines. [Solution] The underground data management device 10 acquires road surface images and underground data along multiple survey lines set so that the shooting range of the road surface images partially overlaps, matching the acquisition positions. It selects a reference survey line from the multiple survey lines, divides the road surface image into multiple blocks along the survey line, and associates the road surface image blocks of the reference survey line with the road surface image blocks of the other survey lines by matching the feature points in the images. This identifies the relative position of the other survey lines with respect to the reference survey line for each block, and manages the underground data for each block based on its relative position with respect to the reference survey line.

Description

Technical Field

[0001] The present disclosure relates to a subsurface data management device, a subsurface data management method, and a subsurface data management program.

Background Art

[0002] For example, in the operation of surveying subsurface data such as the position of buried pipes, there are cases where planar subsurface data is created and analyzed from data acquired by a GPR (Ground Penetrating Radar) device or the like. In this case, since it is necessary to associate the position where the subsurface data was acquired with the subsurface data, for example, a thread is stretched at a point on the road surface where the position information is known, a line is drawn with chalk, etc., to physically construct a survey line, and the GPR device is moved along the survey line to acquire subsurface data. When subsurface data is acquired along a plurality of survey lines within the survey range, the subsurface data created for each survey line is joined together based on the relative position information of each survey line to create subsurface data for the entire survey range. However, physically constructing a survey line takes time and effort. Also, depending on the characteristics of the survey range such as the condition of the road surface, the shape of the survey range, the situation of pedestrians, etc., it may be difficult to construct a physical survey line, for example, only a worker with skills can draw a survey line.

[0003] Also, for example, there are cases where alignment of the subsurface data of each survey line is performed by using an aluminum tape and intentionally causing a reflection signal with respect to the aluminum tape to appear on the subsurface data. However, in an environment where it is not possible to restrict the entry of vehicles other than survey-related persons into the survey range, there is a risk associated with the work of attaching and removing the aluminum tape depending on the traffic situation.

[0004] In addition, instead of aluminum tape, metal structures on the paved surface, such as manholes and gratings, are sometimes used as markers to align underground data. However, aligning underground data for each survey line requires superimposing a common metal structure across all survey lines, but suitable metal structures are not always present within the survey area, making it impossible to use them as a reference for alignment. Furthermore, the measurement width of radar used to acquire underground data is often equal to or less than the width of a vehicle, and superimposing markers for measurement across multiple survey lines is time-consuming, making it difficult to use the same landmark as a reference.

[0005] Recently, a technique has become common to map subsurface data to positional information obtained by GNSS (Global Navigation Satellite System) by linking it with subsurface data. In other words, the movement trajectory of the GPR device is determined based on GNSS data acquired simultaneously with the acquisition of GPR data, and this movement trajectory is then mapped as a survey line. However, in environments where the GNSS satellite environment (position) is poor or where multipath occurs, the accuracy of the positional information may be low, and when the movement trajectory obtained from GNSS is used as a survey line and subsurface data for multiple survey lines is aligned, discrepancies may occur.

[0006] Another method involves attaching a prism to the GPR device and acquiring its position information using a total station fixed to the ground. However, this method has many limitations, such as limiting the survey area to the range where the total station can be installed and only being usable in environments without obstacles.

[0007] Furthermore, methods such as SLAM (Simultaneous Localization and Mapping) using LiDAR (Light Detection and Ranging) or VSLAM (Visual SLAM) using high-resolution cameras to align multiple survey lines using self-localization results can also be considered. However, these methods have not yet reached practical application in terms of accuracy, and their accuracy may be affected by the presence and quantity of feature points of detected objects required for SLAM processing.

[0008] Furthermore, it is conceivable to use the information about pipes and other structures indicated by the underground data as a clue to align the underground data for each survey line. However, interpreting whether or not pipes and other structures in the underground data actually have continuity depends on the experience and skill of the analyst, and therefore, reliability cannot be guaranteed.

[0009] Therefore, a technology has been proposed that acquires road surface images along with underground data, and then aligns the underground data based on the road surface images.

[0010] For example, a ground-penetrating exploration method has been proposed in which a survey vehicle is equipped with multiple ground-penetrating radar sensors arranged along the vehicle width direction or movable in the vehicle width direction, and a road surface image capturing means that photographs the road surface at a predetermined distance from the ground-penetrating radar sensors with a width wider than the exploration width of the ground-penetrating radar sensors and records the captured road surface image and driving information. The survey vehicle is driven multiple times, changing lanes, while the ground-penetrating radar sensors project radar waves below the road surface and the reflected waves are received to obtain exploration information for each lane. After obtaining road surface images of the driving road surface for each lane using the road surface image capturing means, the area below the road surface is explored by synthesizing the exploration information for each lane while referring to the road surface images (see Patent Document 1).

[0011] Furthermore, a ground-penetrating radar system has been proposed that includes, for example, a ground-penetrating radar device having a self-propelled mobile unit to perform ground-penetrating exploration of a target area, and a control device that controls the movement of the ground-penetrating radar device based on image data captured from above of the target area (see Patent Document 2).

[0012] Furthermore, for example, an exploration vehicle consisting of an automobile equipped with multiple wheels including front and rear wheels and capable of traveling on a road surface; underground exploration means disposed on the exploration vehicle and generating three-dimensional underground information beneath the road surface on which the exploration vehicle travels; ground image generation means disposed on the exploration vehicle and generating three-dimensional ground images on the road surface on which the exploration vehicle travels; and the three-dimensional underground information generated by the underground exploration means and the three-dimensional ground images generated by the ground image generation means are combined into unified three-dimensional information from underground to above ground through a predetermined data unification process. A ground-penetrating exploration device has been proposed, comprising a three-dimensional information unification processing means that generates a ground-penetrating exploration means positioned on the bottom surface of the exploration vehicle, between the front and rear wheels, or between the axles of the multiple wheels, the ground image generation means generates a ground orthoimage by converting a three-dimensional ground image of the road surface on which the exploration vehicle travels into an orthographic projection image viewed from directly above, and the three-dimensional information unification processing means generates an unified processed image in which the ground-penetrating three-dimensional information is integrally displayed in the ground orthoimage (see Patent Document 3). [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 3936472 [Patent Document 2] Japanese Patent Publication No. 2024-3679 [Patent Document 3] Japanese Patent Publication No. 6446005 [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] When the survey area covers a long distance, positional discrepancies may accumulate when aligning underground data acquired along multiple survey lines, and optimizing the alignment to achieve overall consistency may be difficult.

[0015] This disclosure is made in view of the above points, and aims to provide a subsurface data management device, method, and program that can accurately align subsurface data acquired along multiple survey lines, even when the survey area covers a long distance. [Means for solving the problem]

[0016] To achieve the above objective, the underground data management device according to this disclosure includes: an acquisition unit that acquires images of the road surface and underground data based on the intensity of reflected electromagnetic waves irradiated from the road surface toward the ground, along a plurality of survey lines set so that the shooting ranges of the images partially overlap, by corresponding the acquisition positions of the images and the underground data; an identification unit that selects a reference survey line from the plurality of survey lines, divides the images corresponding to each of the plurality of survey lines into a plurality of blocks along the survey line, and identifies the relative position of the other survey lines with respect to the reference survey line for each block by matching the feature points in the images of the blocks of the images corresponding to the reference survey line and the blocks of images corresponding to the other survey lines; and a management unit that manages, for each block, by associating the position of the reference survey line with the acquisition positions of the images and underground data acquired along the reference survey line, and by associating the position of the other survey lines identified from their relative positions with respect to the reference survey line with the acquisition positions of the images and underground data acquired along the other survey lines.

[0017] Furthermore, the underground data management method relating to this disclosure is an underground data management method executed by an underground data management device including an acquisition unit, a specification unit, and a management unit, wherein the acquisition unit acquires an image of the road surface and underground data based on the intensity of reflected electromagnetic waves irradiated from the road surface toward the ground, along a plurality of survey lines set so that the shooting ranges of the images partially overlap, by corresponding the acquisition positions of the image and the underground data; the specification unit selects a reference survey line from the plurality of survey lines, divides the image corresponding to each of the plurality of survey lines into a plurality of blocks along the survey line, and relates to the reference survey line The method involves associating a block of the image corresponding to one with a block of the image corresponding to another survey line, such that the feature points in the image match, thereby identifying the relative position of the other survey line with respect to the reference survey line for each block. The management unit then manages each block by associating the position of the reference survey line with the acquisition locations of the image and underground data acquired along the reference survey line, and also by associating the position of the other survey line identified from its relative position with respect to the reference survey line with the acquisition locations of the image and underground data acquired along the other survey line.

[0018] Further, the underground data management program according to the present disclosure causes a computer to obtain an image of a road surface and underground data based on the intensity of a reflected wave of an electromagnetic wave irradiated from the road surface in the underground direction, along a plurality of survey lines set such that the imaging ranges of the images partially overlap, and to associate the acquisition positions with each other using the image and the underground data. The program includes an acquisition unit, a specifying unit, and a management unit. The acquisition unit acquires the image and the underground data while associating the acquisition positions. The specifying unit selects a reference survey line from the plurality of survey lines, divides the image corresponding to each of the plurality of survey lines into a plurality of blocks along the survey line, and associates the block of the image corresponding to the reference survey line with the block of the image corresponding to another survey line so that feature points in the image match, thereby specifying the relative position of the other survey line with respect to the reference survey line for each block. The management unit associates and manages, for each block, the position of the reference survey line with the acquisition positions of the image and the underground data acquired along the reference survey line, and also associates and manages the position of the other survey line specified from the relative position with respect to the reference survey line with the acquisition positions of the image and the underground data acquired along the other survey line.

Advantages of the Invention

[0019] According to the underground data management device, method, and program of the present disclosure, even when the survey range extends over a long distance, the underground data acquired along a plurality of survey lines can be accurately aligned.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic configuration diagram of an underground data management system. [Figure 2] It is a diagram for explaining the generation of a road surface image. [Figure 3] It is a diagram for explaining the generation of underground data. [Figure 4] It is a block diagram showing the hardware configuration of an underground data management device. [Figure 5] It is a block diagram showing an example of the functional configuration of an underground data management device. [Figure 6] It is a diagram showing an example of the division of a survey range. [Figure 7] It is a diagram for explaining the selection of a reference measurement line. [Figure 8] It is a diagram for explaining the division of a road surface image. [Figure 9] It is a diagram for explaining the specification of the relative position of other measurement lines with respect to a reference measurement line. [Figure 10] It is a diagram for explaining a portion not used for matching a road surface image. [Figure 11] It is a diagram for explaining the alignment of underground data based on the relative position with a reference measurement line. [Figure 12] It is a diagram for explaining the management based on the relative position of characteristic points of underground data. [Figure 13] It is a flowchart showing the flow of an underground data management process. [Figure 14] It is a diagram for explaining another example of the selection of a reference measurement line. [Figure 15] It is a diagram for explaining the correction of a reference measurement line.

Mode for Carrying Out the Invention

[0021] Hereinafter, an example of an embodiment of the present disclosure will be described while referring to the drawings. In each of the drawings, the same or equivalent components and parts are given the same reference numerals. Also, the dimensions and ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0022] FIG. 1 is a diagram showing a schematic configuration of an underground data management system 100 according to the present embodiment. The underground data management system 100 includes a road surface camera 50, an electromagnetic wave device 60, a GNSS 70, and a processing device 80 mounted on a vehicle 90, and an underground data management device 10 arranged in a predetermined facility such as a company.

[0023] The road surface camera 50 is, for example, a line scan camera and has multiple light-receiving units on a line perpendicular to the direction of movement of the vehicle 90. The road surface camera 50 captures line images as shown in Figure 2A at each position along each of the multiple survey lines that are set to cover the entire survey area and whose image capture ranges partially overlap. The road surface camera 50 outputs the captured line images to the processing unit 80.

[0024] Furthermore, the road surface camera 50 is not limited to a line scan camera; it may also be a general two-dimensional camera, a color camera, a monochrome camera, an infrared camera, or any other camera that detects reflectivity at a specific wavelength, and its type is not limited.

[0025] The electromagnetic wave device 60 is equipped with multiple electromagnetic wave irradiating and receiving units on a line perpendicular to the direction of movement of the vehicle 90. The electromagnetic wave device 60 irradiates electromagnetic waves from the road surface toward the ground (depth direction) at each position along each of the multiple survey lines and receives the reflected waves. This allows the reflected wave intensity corresponding to the depth to be detected for each grid in the survey area. The depth corresponds to the time from irradiation of the electromagnetic waves to reception of the reflected waves. The reflected wave intensity corresponding to the depth is detected for each grid in the form of a reflected response waveform as shown in Figure 3A. The electromagnetic wave device 60 outputs the reflected response waveform for each grid detected along the multiple survey lines to the processing unit 80.

[0026] The GNSS 70 determines the position information (latitude and longitude) of the vehicle 90 at predetermined sampling intervals and outputs the determined position information to the processing unit 80.

[0027] The processing unit 80 calculates the movement trajectory of the vehicle 90 from the position information output from the GNSS 70. The movement trajectory of the vehicle 90 corresponds to the survey line. The processing unit 80 associates the line images of each line captured by the road surface camera 50 and the reflection response waveforms of each line detected by the electromagnetic wave device 60 with each point on the movement trajectory according to the timing of their acquisition.

[0028] Furthermore, as shown in Figure 2B, the processing unit 80 generates a road surface image by arranging the line images output from the road surface camera 50 along the survey line in the direction of vehicle travel and stitching them together.

[0029] Furthermore, the processing unit 80 generates subsurface data from the reflected response waveform output from the electromagnetic wave device 60. Specifically, the processing unit 80 replaces the reflected wave intensity of each grid with pixel values ​​(shades of gray and white) for each depth and arranges them along the survey line in the direction of vehicle travel, as shown in Figure 3B. The processing unit 80 also generates planar images for each depth by extracting pixel values ​​corresponding to each desired depth of each grid. The processing unit 80 generates three-dimensional subsurface data by stacking the planar images for each depth, as shown in Figure 2C.

[0030] The processing unit 80 transmits the generated road surface image, underground data, and movement trajectory (survey line) to the underground data management device 10. If the survey area is measured along multiple survey lines, the road surface image and underground data for each survey line are transmitted. Note that the data is not limited to being transmitted from the processing unit 80; it may also be stored on a storage medium and read by the underground data management device 10. Alternatively, the underground data management device 10 itself may be mounted on the vehicle 90, and the data may be directly input to the underground data management device 10.

[0031] The underground data management device 10 is an information processing device such as a personal computer or a tablet terminal. Figure 4 is a block diagram showing the hardware configuration of the underground data management device 10 according to this embodiment. As shown in Figure 4, the underground data management device 10 has a CPU (Central Processing Unit) 12, memory 14, storage device 16, input device 18, output device 20, storage medium reader 22, and communication I / F (Interface) 24. Each component is connected to each other so as to be able to communicate with each other via a bus 26.

[0032] The storage device 16 stores an underground data management program for executing the underground data management processing described later. The CPU 12 is a central processing unit that executes various programs and controls each component. Specifically, the CPU 12 reads a program from the storage device 16 and executes the program using memory 14 as a working area. The CPU 12 controls each component and performs various calculations according to the program stored in the storage device 16.

[0033] Memory 14 is composed of RAM (Random Access Memory) and temporarily stores programs and data as a working area. Storage device 16 is composed of ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), etc., and stores various programs and data, including the operating system.

[0034] The input device 18 is a device for performing various types of input, such as a keyboard or mouse. The output device 20 is a device for outputting various types of information, such as a display or printer. By using a touch panel display as the output device 20, it may also function as the input device 18.

[0035] The storage medium reader 22 reads data stored on various storage media such as CD (Compact Disc)-ROM, DVD (Digital Versatile Disc)-ROM, Blu-ray disc, and USB (Universal Serial Bus) memory, and writes data to the storage media. The communication I / F 24 is an interface for communication with other devices, and standards such as Ethernet (registered trademark), FDDI, or Wi-Fi (registered trademark) are used.

[0036] Next, the functional configuration of the underground data management device 10 according to this embodiment will be described. Figure 5 is a block diagram showing an example of the functional configuration of the underground data management device 10. As shown in Figure 5, the underground data management device 10 includes, as a functional configuration, an acquisition unit 32, a identification unit 34, and a management unit 36. In addition, an underground data DB 38 is stored in a predetermined storage area of ​​the underground data management device 10. Each functional configuration is realized by the CPU 12 reading the underground data management program stored in the storage device 16, expanding it into the memory 14, and executing it.

[0037] The acquisition unit 32 acquires road surface images and underground data for each survey line, as well as the movement trajectory (survey line), transmitted from the processing unit 80. As described above, the road surface images for each survey line are taken so that their shooting ranges partially overlap. In addition, the acquisition locations of the road surface images and underground data are associated via the survey lines. The acquisition unit 32 then passes each acquired data to the identification unit 34.

[0038] The specific unit 34 divides the survey area into multiple blocks. Figure 6 shows an example of this division. In the example in Figure 6, the area is divided into blocks at predetermined distances (100m intervals in the example in Figure 6) along the extension direction of the survey line.

[0039] Furthermore, the identification unit 34 selects a reference survey line from among multiple survey lines. Specifically, the identification unit 34 selects, as the reference survey line, the survey line closest to the center, the survey line closest to a straight line, or the survey line from which positional information was acquired most stably. For example, in the example in Figure 6, the identification unit 34 may select survey line 2, which is the middle survey line among survey lines 1, survey line 2, and survey line 3, as the reference survey line. Alternatively, the identification unit 34 may exclude survey line 3, which does not pass through block 3, and select survey line 2 as the reference survey line on the grounds that it is closer to a straight line. Whether or not a survey line is close to a straight line can be determined, for example, by the magnitude of the error between each survey line and its approximate straight line.

[0040] Furthermore, the identification unit 34 may determine the survey line from which positional information was acquired most stably based on at least one of the following: the reception strength of radio waves from satellites using GNSS 70, the change in the vehicle's speed, and the change in the vehicle's direction of travel. The identification unit 34 may, for example, calculate the average reception strength of radio waves for each survey line and select the survey line with the highest average as the reference survey line.

[0041] Furthermore, for example, as shown in Figure 7, the vehicle speed and direction of travel of the vehicle 90 are obtained. The vehicle speed and direction of travel may be calculated from the trajectory, or obtained from a vehicle speed sensor and a gyro sensor (not shown) installed on the vehicle 90. The identification unit 34 identifies sections where the change in vehicle speed is greater than or equal to a predetermined value as sections with acceleration and deceleration (within the dashed line frame in Figure 7), sections where the change in direction of travel is greater than or equal to a predetermined value as sections where the direction of travel changes (within the dashed line frame in Figure 7), and identifies all other sections as stable driving sections. The identification unit 34 identifies stable driving sections for each survey line and may select the survey line with the longest stable driving section as the reference survey line.

[0042] Furthermore, as shown in Figure 8, the identification unit 34 uses the portion of the road surface image corresponding to each of the multiple survey lines that corresponds to the divided blocks to determine the relative position of the other survey lines with respect to the reference survey line, block by block. Specifically, as shown in Figure 9, the identification unit 34 associates the road surface image block corresponding to the reference survey line with the road surface image block corresponding to the other survey lines so that the feature points in the images match. The identification unit 34 deforms the road surface image of the other survey lines, for example, by affine transformation, to match the road surface image of the reference survey line, and deforms the other survey lines in accordance with the deformation of the road surface image of the other survey lines, thereby determining the relative position of the other survey lines with respect to the reference survey line. The example in Figure 9 shows a case where survey line 2 is the reference survey line, and the U-turn marks included in the overlapping area of ​​the road surface image of survey line 1 and the road surface image of survey line 2 are matched to determine the relative position of survey line 1 with respect to survey line 2.

[0043] Furthermore, the matching process between the road surface image of the reference survey line and the road surface images of other survey lines is not limited to being performed automatically using image matching technology; it may also be performed manually by a person, or the results of the automatically matched images may be manually corrected by a person. In addition, the matching process is not limited to matching the road surface image of the reference survey line and the road surface image of other survey lines to a perfect match; it may also be performed using the least squares method or other methods to minimize the overall amount of misalignment.

[0044] Furthermore, when performing road surface image matching, the specific unit 34 may choose not to use parts of the road surface image that have not been acquired with a predetermined accuracy, such as parts of the road surface image that are distorted due to vibrations of the vehicle 90, for matching. Specifically, the specific unit 34 considers parts where the movement trajectory fluctuation exceeds a predetermined value, or parts where the output fluctuation of the speed sensor, gyro sensor, etc. exceeds a predetermined value, as parts where vibration has occurred, and marks them on the road surface image (dashed line frame in Figure 10) as shown in Figure 10. The specific unit 34 then avoids selecting feature points from these marked parts when performing road surface image matching.

[0045] The management unit 36 ​​stores in the underground data DB 38, for each block, the position of the reference survey line and the acquisition locations of road surface images and underground data acquired along the reference survey line, in association with each other. The management unit 36 ​​also stores in the underground data DB 38 the positions of other survey lines identified from their relative positions to the reference survey line and the acquisition locations of road surface images and underground data acquired along the other survey lines, in association with each other. As a result, as shown in Figure 11, the underground data of the reference survey line and the underground data of the other survey lines are aligned and positioned based on the identified relative positional relationship. In the example in Figure 11, the underground data of survey line 1, which is another survey line, is transformed based on the relative position of survey line 1 with respect to survey line 2, which is the reference survey line, and then aligned with the underground data of survey line 1.

[0046] Furthermore, the management unit 36 ​​may manage the position of feature points in the underground data in terms of their relative position to the reference survey line. For example, as shown in Figure 12, the position of feature points in the underground data (black circles in Figure 12) may be managed by the distance from an origin (white circle in Figure 12) set at an arbitrary position on the reference survey line, and the orientation (angle) with respect to the tangential direction at the origin of the reference survey line.

[0047] Next, the operation of the underground data management system 100 according to this embodiment will be described.

[0048] As vehicle 90 moves, the road camera 50 starts taking images, the electromagnetic wave device 60 starts detection, and the GNSS 70 starts positioning. The line image taken by the road camera 50, the reflected response waveform detected by the electromagnetic wave device 60, and the position information determined by GNSS 70 are output to the processing unit 80. The processing unit 80 generates underground data from the reflected response waveform, generates a road surface image from the line image, generates a movement trajectory (survey line) from the position information, and transmits it to the underground data management device 10.

[0049] The underground data management device 10 performs underground data management processing. Figure 13 is a flowchart showing the flow of underground data management processing performed by the CPU 12 of the underground data management device 10. The CPU 12 reads the underground data management program from the storage device 16, loads it into the memory 14, and executes it. As a result, the CPU 12 functions as one of the various functional configurations of the underground data management device 10, and the underground data management processing shown in Figure 13 is executed. Note that the underground data management processing is an example of the underground data management method of this disclosure.

[0050] First, in step S10, the acquisition unit 32 acquires road surface images and underground data for each survey line, as well as the movement trajectory (survey line), transmitted from the processing unit 80. Next, in step S12, the identification unit 34 divides the survey area into multiple blocks. Then, the identification unit 34 selects from the multiple survey lines, for example, the survey line closest to the center, the survey line closest to a straight line, or the survey line from which positional information was acquired most stably, as the reference survey line.

[0051] Next, in step S14, the identification unit 34 matches, for each block, the road surface image block corresponding to the reference survey line with the road surface image block corresponding to the other survey lines, so that the feature points in the images match. Then, the identification unit 34 deforms the road surface images of the other survey lines, for example by affine transformation, so that they match the road surface image of the reference survey line, and deforms the other survey lines in accordance with the deformation of the road surface images of the other survey lines, thereby determining the relative positions of the other survey lines with respect to the reference survey line.

[0052] Next, in step S16, the management unit 36 ​​stores in the underground data DB 38, for each block, the location of the reference survey line and the acquisition locations of road surface images and underground data acquired along the reference survey line, in association with each other. The management unit 36 ​​also stores in the underground data DB 38 the locations of other survey lines identified from their relative positions to the reference survey line and the acquisition locations of road surface images and underground data acquired along the other survey lines, in association with each other. In this way, underground data is managed for each block based on relative positions with respect to the reference survey line, and the underground data management process is completed.

[0053] As described above, according to the underground data management system of this embodiment, the underground data management device acquires road surface images and underground data along multiple survey lines set so that the shooting ranges of the road surface images partially overlap, and associates the acquisition positions of the road surface images and underground data. The underground data management device also selects a reference survey line from the multiple survey lines and divides the road surface images corresponding to each of the multiple survey lines into multiple blocks along the survey line. The underground data management device also identifies the relative position of the other survey lines with respect to the reference survey line for each block by associating the image blocks corresponding to the reference survey line with the image blocks corresponding to the other survey lines so that the feature points in the images match. The underground data management device then manages the position of the reference survey line and the acquisition positions of the images and underground data acquired along the reference survey line for each block. Furthermore, the underground data management device manages the positions of the other survey lines identified from their relative positions with respect to the reference survey line and the acquisition positions of the images and underground data acquired along the other survey lines. This allows for accurate alignment of underground data acquired along multiple survey lines, even when the survey area spans long distances.

[0054] In other words, the underground data management device according to this embodiment selects a reference survey line from multiple survey lines and divides the survey area into multiple blocks, managing underground data in relation to the reference survey line. This suppresses misalignment of underground data for each survey line and enables highly accurate alignment compared to aligning long-distance underground data without dividing it into blocks.

[0055] In this embodiment, since the underground data is aligned for each block, some inconsistencies may occur between blocks. However, for example, when the underground data managed by the underground data management device according to this embodiment is referenced when conducting test excavations for roads, the underground data of the block containing the location of the test excavation target will be referenced, so inconsistencies between blocks will not be a major problem. Alternatively, the alignment between blocks may be corrected based on information such as buried pipes that appear in the underground data.

[0056] In the above embodiment, the case in which the vehicle's movement trajectory generated from position information determined by GNSS is used as the survey line was described, but the invention is not limited to this. For example, a movement trajectory estimated by self-position estimation such as SLAM or VSLAM, or a movement trajectory identified based on the accumulation of measurement values ​​from an inertial measuring device, may be used as the survey line. Also, as shown in Figure 14, information that can serve as a reference for the survey line, such as the boundary between road and sidewalk, or the lane, may be detected from the road surface image within the survey area and used as the reference survey line.

[0057] In the case of a movement trajectory generated from position information determined by GNSS (hereinafter referred to as "GNSS trajectory"), there is a possibility that accuracy may be reduced at certain locations due to the satellite configuration and the effects of multipath. Also, in the case of a movement trajectory identified based on the accumulation of measurements from an inertial measurement device (hereinafter referred to as "IMU trajectory"), errors accumulate at each location, and the deviation from the actual movement trajectory increases as the length of the movement trajectory increases. Therefore, the IMU trajectory may be acquired as a survey line, and as shown in Figure 15, the uncorrected IMU trajectory showing the selected reference survey line may be corrected so that the position of the corresponding point on the IMU trajectory matches the position of the representative point on the GNSS trajectory. Representative points on the GNSS trajectory may be, for example, positioning points where the received signal strength from satellites is above a predetermined value, or positioning points within the stable driving section explained in Figure 7. Furthermore, as a correction method, a process equivalent to loop closure in SLAM may be used, where a representative point on the GNSS trajectory is matched with a point on the IMU trajectory corresponding to that representative point, and pose adjustment is performed using a constrained least squares method or similar so that the pitch of the IMU trajectory does not change significantly.

[0058] Furthermore, while the above embodiment describes a case where the road camera, electromagnetic wave device, and GNSS are mounted on a vehicle, the invention is not limited to this. For example, these devices may be mounted on a hand-pushed cart.

[0059] Furthermore, a portion of the processing performed by the processing device in the above embodiment may be performed by the underground data management device. For example, line images captured by a road surface camera, reflection response waveforms detected by an electromagnetic wave device, and position information determined by GNSS may be transmitted to the underground data management device, and the underground data management device may generate road surface images, underground data, and movement trajectories for each survey line.

[0060] Furthermore, although the above embodiment described an example of investigating buried pipes and the like under the road surface as underground data, it is not limited to this. For example, the technology disclosed can also be applied to deterioration diagnosis surveys of bridges, pavements, etc., and sinkhole prevention surveys that investigate voids under the road surface, etc.

[0061] Furthermore, the underground data management processing that the CPU reads and executes in the above embodiment may be executed by various processors other than the CPU. Examples of such processors include PLDs (Programmable Logic Devices) such as FPGAs (Field-Programmable Gate Arrays) whose circuit configuration can be changed after manufacturing, and dedicated electrical circuits that are processors with circuit configurations specifically designed to execute specific processing, such as ASICs (Application Specific Integrated Circuits). The underground data management processing may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0062] Furthermore, although the above embodiment describes a configuration in which the underground data management program is pre-stored (installed) in a storage device, the system is not limited to this. The program may be provided in a form recorded on a recording medium such as a CD-ROM, DVD-ROM, or USB memory. Alternatively, the program may be provided in a form that can be downloaded from an external device via a network. [Explanation of Symbols]

[0063] 10 Underground data management device 12 CPU 14 memory 16 Storage device 18 Input device 20 Output device 22 Storage medium reader 24 Communication I / F 26 bus 32 Acquisition Department 34 Specific part 36 Management Department 38 Underground Data Database 50 Roadside cameras 60 Electromagnetic wave equipment 80 Processing Unit 90 vehicles 100 Underground Data Management Systems

Claims

1. An acquisition unit acquires images of the road surface and underground data based on the intensity of reflected electromagnetic waves irradiated from the road surface toward the ground, along multiple survey lines set so that the shooting ranges of the images partially overlap, by corresponding the acquisition locations of the images and the underground data. A unit that identifies the relative position of the other survey lines with respect to the reference survey line for each block by selecting a reference survey line from the plurality of survey lines, dividing the image corresponding to each of the plurality of survey lines into a plurality of blocks along the survey line, and associating the block of the image corresponding to the reference survey line with the block of the image corresponding to the other survey lines so that the feature points in the image match, For each of the aforementioned blocks, a management unit manages the position of the reference survey line and the acquisition locations of the images and underground data acquired along the reference survey line in association with each other, and manages the position of other survey lines identified from their relative positions to the reference survey line and the acquisition locations of the images and underground data acquired along the other survey lines in association with each other, An underground data management device, including one.

2. The underground data management device according to claim 1, wherein the specified unit selects, as the reference survey line, the survey line closest to the center, the survey line closest to a straight line, or the survey line from which the acquisition position was most stably obtained among the plurality of survey lines.

3. The underground data management device according to claim 2, wherein the identifying unit determines the survey line on which the acquisition position was most stably acquired based on at least one of the received signal strength from the satellite when the acquisition position is determined by GNSS, the change in the movement speed of the system that acquires the underground data, and the change in the direction of travel of the system.

4. The underground data management device according to any one of claims 1 to 3, wherein the specified unit excludes portions of the image that have not been acquired with a predetermined accuracy from the feature points in the image when associating the image blocks corresponding to the reference survey line with the image blocks corresponding to the other survey lines.

5. The acquisition unit acquires the trajectory of the acquisition position of the image and the underground data, which is identified based on the accumulation of measurement values ​​from the inertial measuring device, as the survey line. The specified unit corrects the trajectory indicating the reference survey line so that the corresponding position on the trajectory matches the position determined by GNSS with an accuracy of a standard value or higher. The underground data management device according to any one of claims 1 to 3.

6. An underground data management method performed by an underground data management device including an acquisition unit, a specification unit, and a management unit, The acquisition unit acquires an image of the road surface and underground data based on the intensity of reflected electromagnetic waves irradiated from the road surface toward the ground, along multiple survey lines set so that the shooting ranges of the images partially overlap, by matching the acquisition locations of the image and the underground data. The identifying unit selects a reference survey line from the plurality of survey lines, divides the image corresponding to each of the plurality of survey lines into a plurality of blocks along the survey line, and associates the image block corresponding to the reference survey line with the image block corresponding to the other survey lines so that the feature points in the image match, thereby identifying the relative position of the other survey lines with respect to the reference survey line for each block. The management unit manages, for each block, the position of the reference survey line and the acquisition locations of the images and underground data acquired along the reference survey line, and also manages, for each block, the position of the other survey lines identified from their relative position to the reference survey line and the acquisition locations of the images and underground data acquired along the other survey lines. Methods for managing underground data.

7. Computers, An acquisition unit acquires images of the road surface and underground data based on the intensity of reflected electromagnetic waves irradiated from the road surface toward the ground, along multiple survey lines set so that the shooting ranges of the images partially overlap, by matching the acquisition locations of the images and the underground data. A unit for identifying the relative position of the other survey lines with respect to the reference survey line, by selecting a reference survey line from the plurality of survey lines, dividing the image corresponding to each of the plurality of survey lines into a plurality of blocks along the survey line, and associating the image block corresponding to the reference survey line with the image block corresponding to the other survey line so that the feature points in the image match, and A management unit manages, for each block, the position of the reference survey line and the acquisition locations of the images and underground data acquired along the reference survey line in association with each other, and manages, for each block, the position of the other survey line identified from its relative position to the reference survey line and the acquisition locations of the images and underground data acquired along the other survey line in association with each other, A subsurface data management program designed to function as such.

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