Information processing device, information processing method, and computer program

Abstract

This information processing device comprises a control unit that, on the basis of displacement information relating to ground surface displacement analyzed on the basis of a synthetic aperture radar image and traffic information relating to a region in which the ground surface displacement has occurred, calculates an impact degree indicating the magnitude of impact of the ground surface displacement on a traffic network.

Description

Information processing device, information processing method, and computer program

[0001] This disclosure relates to an information processing device, an information processing method, and a computer program. This application claims priority to Japanese Application No. 2024-112167, filed on July 12, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] In order to understand ground surface displacements such as subsidence and uplift, SAR images acquired by a SAR (Synthetic Aperture Radar) mounted on an artificial satellite are sometimes used. SAR images are information obtained by emitting radio waves from a SAR mounted on an aircraft device such as an artificial satellite toward the ground surface and receiving the radio waves reflected from the ground surface with a sensor on the aircraft device.

[0003] Patent Document 1 discloses a technology for observing ground deformation such as subsidence, which is likely to occur during tunnel construction, by measuring the relative height change of the ground surface corresponding to the tunnel route using SAR and determining the amount of ground surface displacement through SAR interferometry analysis.

[0004] Patent Literature 2 discloses a technology for extracting points requiring emergency inspection or repair from a large number of analysis points obtained by SAR image analysis. Specifically, among the multiple analysis points extracted based on SAR image data, points with a displacement amount greater than or equal to a predetermined amount are identified and identified as analysis points with a high level of urgency. Furthermore, among the multiple analysis points, analysis points where the correlation with the time-series displacement of measurement values ​​from a water level meter installed within the observation range has collapsed are extracted as points requiring attention from the perspective of landslides.

[0005] JP 2019-132707 A JP 2020-020740 A

[0006] The information processing device of the present disclosure includes a control unit that calculates an impact level indicating the magnitude of the impact that the ground displacement has on a transportation network, based on displacement information regarding ground displacement analyzed based on synthetic aperture radar images and traffic information regarding the area where the ground displacement has occurred.

[0007] FIG. 1 is a schematic diagram showing an example of the configuration of an information providing system. FIG. 2 is a flowchart illustrating a series of processes executed by a control unit. FIG. 3 is an example of a screen displayed on a display device of a user terminal. FIG. 4 is a schematic diagram showing a state in which DRM is superimposed on displacement information. FIG. 5 is a table illustrating the relationship between various parameters and influence degrees. FIG. 6 is a schematic diagram showing an example of evaluation information.

[0008] By using SAR images acquired by aircraft devices such as satellites, it is possible to observe surface displacements (also known as crustal movements) such as uplift and subsidence over a wide area of ​​the earth's surface. However, it is necessary to narrow down these surface displacements to those that have a significant impact on people's lives. For example, even if a large amount of surface displacement is observed, if the point where the surface displacement occurred is located deep in the jungle with no houses or transportation, there is little need to focus on that surface displacement. In contrast, if the point is one with a lot of traffic, there is a greater need to focus on the surface displacement at that point, even if the amount of displacement is not that large.

[0009] In this regard, in Patent Document 1, a predetermined area of ​​the tunnel route is set as the region of interest. In special circumstances, such as when tunnel construction is currently underway, a method can be adopted in which a specific area is set and then the amount of displacement in that area is observed. However, if, for example, the area where repair work or the like should be carried out has not yet been determined, the technology in Patent Document 1 cannot be used.

[0010] In Patent Document 2, points where the amount of ground surface displacement is large are extracted, but the amount of ground surface displacement alone is not enough to measure the impact on people's lives. In addition, in Patent Document 2, analysis points are extracted by also taking into account the measurement values ​​of water level gauges, but this also simply extracts points where landslides are likely to occur as analysis points, and it is not possible to measure whether a landslide will have a major impact on people's lives.

[0011] In view of the above-described conventional problems, the present disclosure aims to provide an information processing device and the like that can suitably evaluate, based on SAR images, ground surface displacement that has a significant impact on people's lives.

[0012] According to the present disclosure, it is possible to suitably evaluate ground surface displacement, which has a large impact on people's lives.

[0013] The following provides an outline of embodiments of the present disclosure.

[0014] (1) An information processing device according to an embodiment of the present disclosure includes a control unit that calculates an impact level indicating the magnitude of the impact that the ground displacement has on a transportation network, based on displacement information regarding ground displacement analyzed based on a synthetic aperture radar image and traffic information regarding the area in which the ground displacement has occurred.

[0015] According to the present disclosure, the impact of ground surface displacement on the transportation network is evaluated by taking into account not only displacement information but also traffic information, making it possible to appropriately evaluate ground surface displacement that has a significant impact on people's lives.

[0016] (2) In the information processing device of (1) described above, the control unit may extract at least one of the areas through which the road passes and the areas adjacent to the road as a target area based on road map information and the displacement information, and calculate the influence of the target area based on the traffic information related to the target area.

[0017] By calculating the degree of impact in areas where ground surface displacement may have an impact on the transportation network, the processing load on the control unit can be reduced.

[0018] (3) In the information processing device of (2) described above, the control unit may extract, based on the displacement information, a displacement area where the absolute value of the displacement amount of the ground surface displacement is equal to or greater than a predetermined first threshold value, and, based on the road map information, extract at least one of the areas of the displacement area through which a road passes and areas close to the road as the target area.

[0019] When the magnitude of ground surface displacement is small, it is thought that such displacement will have little impact on people's lives. Therefore, by excluding areas with small displacement from the calculation of the impact degree using threshold processing, the processing load on the control unit can be reduced.

[0020] (4) In the information processing device of (2) or (3) described above, the traffic information includes information regarding traffic volume of roads passing through or close to the target area, and the control unit may calculate the influence degree to be greater when the traffic volume for multiple target areas is the same, as the amount of displacement of the ground surface displacement is greater.

[0021] (5) In the information processing device of (2) or (3) described above, the traffic information includes information regarding traffic volume of roads passing through or close to the target area, and the control unit may calculate the influence degree to be greater when the amount of ground surface displacement in multiple target areas is the same, as the traffic volume in the target area is greater.

[0022] (6) In the information processing device of (2) or (3) above, the traffic information includes information regarding the presence or absence of a detour route when a road passing through or close to the target area is closed, and the control unit may calculate the impact level to be greater when there is no detour route than when there is a detour route when the amount of displacement of the ground surface displacement in multiple target areas is the same.

[0023] (7) In the information processing device of (2) or (3) described above, the traffic information includes information regarding the presence or absence of a detour route when a road passing through or close to the target area is closed, and the increased travel time, which is the increased travel time when traveling via the detour route compared to traveling via the actual road, and the control unit may calculate the impact level to be greater the longer the increased travel time when the amount of displacement of the ground surface displacement in multiple target areas is the same and when a detour route is available.

[0024] According to the information processing device described in (4) to (7) above, by taking into account not only ground surface displacement but also traffic information, it is possible to appropriately evaluate ground surface displacement, which has a large impact on people's lives.

[0025] (8) In the information processing device of (2) to (7) above, the control unit may output evaluation information including the influence levels in the plurality of target areas to a display device connected to the information processing device or a user terminal communicating with the information processing device, thereby allowing a user or the like to know the evaluation information including the influence levels.

[0026] (9) An information processing method according to an embodiment of the present disclosure includes a calculation step of calculating an influence degree indicating the magnitude of an influence of the ground surface displacement on a transportation network based on displacement information related to the ground surface displacement analyzed based on a synthetic aperture radar image and traffic information related to an area where the ground surface displacement has occurred. The information processing method according to the present disclosure achieves the same effects as the information processing device described above in (1).

[0027] (10) A computer program according to an embodiment of the present disclosure causes a computer to function as an information processing device. The computer program causes the computer to execute a calculation step of calculating an impact level indicating the magnitude of the impact of the ground surface displacement on a transportation network, based on displacement information regarding the ground surface displacement analyzed based on synthetic aperture radar images and traffic information regarding an area where the ground surface displacement has occurred. The computer program of the present disclosure achieves the same effects as the information processing device described above in (1).

[0028] Hereinafter, details of embodiments of the present disclosure will be described with reference to the drawings. Note that at least some of the embodiments described below may be combined in any manner.

[0029] 1 is a schematic diagram showing an example of the configuration of an information providing system 1. The information providing system 1 includes an information providing server 2, a user terminal 3, and an SAR image server 4. The information providing server 2, the user terminal 3, and the SAR image server 4 are communicably connected to each other via a public communication network 5 such as the Internet. In the information providing system 1, the information providing server 2 functions as an information processing device of this embodiment.

[0030] The information provision system 1 is a system that generates evaluation information with an impact level indicating the magnitude of the impact that ground surface displacement observed based on SAR images has on a transportation network, and provides the evaluation information to a user terminal 3. The information provision system 1 may be used by road management companies that manage points requiring repair such as slopes (for example, points that are likely to be subject to cliff collapse due to heavy rain if left as is), by survey companies that extract and survey points requiring repair from a wide transportation network, or by information service companies that provide information to these companies.

[0031] The information providing server 2 (hereinafter referred to as "server 2") is a server operated by, for example, a road management company, a research company, or an information service company. The server 2 may be either an on-premise server or a cloud server.

[0032] The user terminal 3 is a device that receives information such as evaluation information from the server 2. The user terminal 3 is a stationary terminal such as a desktop computer installed indoors, and communicates with the server 2 via the public communication network 5. The user terminal 3 may also be a mobile terminal such as a smartphone or a tablet computer.

[0033] For example, if a survey company operates the server 2, a road management company other than the survey company uses the user terminal 3 and receives information from the server 2 in order to narrow down the points on the road that need repair. If a road management company operates the server 2, the road management company may also use the user terminal 3. In this way, in the information provision system 1, the server 2 and the user terminal 3 may be used by different entities or by the same entity. The server 2 may transmit evaluation information to a user terminal 3 installed in a country different from the country in which the server 2 is installed.

[0034] The SAR image server 4 is a server that provides SAR images to the server 2. SAR images are acquired by observing the Earth's surface from the sky using a SAR (Synthetic Aperture Radar) mounted on an aircraft device. The aircraft device may be, for example, an artificial satellite, but may also be an airship, a manned aircraft, or an unmanned aircraft (such as a drone) that flies at a lower altitude. The SAR image is data that expresses, as brightness values, the gray level corresponding to the backscattering intensity at each point on the Earth's surface. The SAR image server 4 is operated by a private company or government agency that distributes SAR images.

[0035] [Configuration of Information Providing Server] The information providing server 2 includes a control unit 21, a storage unit 22, and a communication unit 23. The control unit 21, the storage unit 22, and the communication unit 23 are electrically connected to each other via a bus. The server 2 is further connected to an input device 24 and a display device 25.

[0036] The server 2 is, for example, a single server computer. The server 2 may be configured with multiple computers. When configured with multiple computers, the multiple computers may be installed in the same facility or may be scattered across multiple locations that are geographically separated. When the server 2 is configured with multiple computers, the multiple computers may cooperate via a network such as the public communication network 5 to realize the functions of a single server 2.

[0037] The control unit 21 is an arithmetic processing device including a CPU (Central Processing Unit) and a RAM (Random Access Memory). The control unit 21 may include an integrated circuit other than the CPU, such as an FPGA (Field-Programmable Gate Array). The control unit 21 reads a computer program 221 stored in the storage unit 22 into the RAM, and performs predetermined information processing in accordance with the read computer program 221.

[0038] The storage unit 22 is an auxiliary storage device including a non-volatile memory such as a hard disk drive (HDD) and a solid state drive (SSD). The storage unit 22 may include a flash read-only memory (ROM), a universal serial bus (USB) memory, or an SD card. The storage unit 22 stores a computer program 221 and various parameters in the non-volatile memory. The computer program 221 and various parameters are stored in the storage unit 22 so as to be readable from a recording medium via a reading device (not shown) provided in the server 2. The computer program 221 and various parameters may be stored in the storage unit 22 by being downloaded from another computer via the public communication network 5. The storage unit 22 further includes a storage area for constructing a database 26.

[0039] The communication unit 23 is a communication interface that communicates with the user terminal 3 and the SAR image server 4 via the public communication network 5. The communication unit 23 periodically receives SAR images from the SAR image server 4. The communication unit 23 transmits evaluation information to the user terminal 3 in response to a request from the user terminal 3 or periodically.

[0040] The input device 24 is an input device such as a mouse and a keyboard, and is operated by the administrator of the server 2. The display device 25 is a display device such as a display, and displays various information such as SAR images to the administrator of the server 2. The input device 24 and the display device 25 may be integrated into one device, such as a touch panel.

[0041] The database 26 is constructed in a large-capacity storage such as an HDD or SSD included in the storage unit 22. The large-capacity storage of the storage unit 22 may be one or more external storage devices connected to the server 2. The database 26 may also be constructed in the storage of a cloud service operated by a company other than the company that manages the server 2.

[0042] In this way, the memory unit 22 in the sense of storage on which the database 26 is constructed may be, from the perspective of the information providing server 2, a memory unit of its own device (a memory unit within the server 2), or an external device (a memory unit outside the server 2, such as the above-mentioned external storage device or cloud server).

[0043] The database 26 includes a SAR image database (SAR DB) 261, a DEM (Digital Elevation Model) database (DEM DB) 262, a displacement information database (displacement information DB) 263, a map database (map DB) 264, and a traffic information database (traffic information DB) 265.

[0044] The SAR image database 261 stores SAR images that are periodically provided from the SAR image server 4. When a plurality of SAR images that observe the same area of ​​the Earth's surface and were generated at different times are input to the SAR image database 261, these SAR images are not overwritten by newer SAR images, but are instead saved (archived) together in chronological order.

[0045] DEM data is stored in the DEM database 262. The DEM data is data that displays elevation values ​​of the earth's surface, and is provided by public organizations such as the Geospatial Information Authority of Japan and the United States Geological Survey (USGS). The DEM data may be downloaded to the DEM database 262 via the public communication network 5, or may be stored in the DEM database 262 in a readable form from a recording medium such as a USB memory.

[0046] It should be noted that DTM (Digital Terrain Model) data may be used instead of DEM data. DEM data is obtained by observing the earth's surface using, for example, a laser mounted on an aircraft device. In this case, if there are buildings or trees on the earth's surface, the DEM data directly represents the elevation values ​​of the surfaces of the buildings or trees (or the rooftops of buildings). In contrast, DTM data is obtained by post-processing the DEM data to remove the heights of the buildings and trees and purely represent the elevation values ​​of the earth's surface.

[0047] The displacement information database 263 stores displacement information. The displacement information is information about ground surface displacement between certain points in time, which is acquired by the control unit 21 analyzing SAR images and DEM data (or DTM data). The displacement information includes, for example, the amount of displacement (amount of uplift or amount of subsidence) of ground surface displacement. A specific method for acquiring the displacement information will be described later.

[0048] The map database 264 stores road map information. The road map information is, for example, a digital road map (DRM) that digitally represents road maps of all of Japan. The DRM includes "intersection data" and "link data." The "intersection data" is data that associates intersection IDs assigned to domestic intersections with location information of the intersections. The "link data" is data that associates the following information a to e with link IDs of specific links assigned to domestic roads.

[0049] Information a: Position information of the start point, end point, and interpolation point of a specific link Information b: Link ID connected to the start point of a specific link Information c: Link ID connected to the end point of a specific link Information d: Link cost of a specific link

[0050] The DRM forms a network corresponding to the actual road alignment and driving direction of the road. In other words, the DRM is a network in which road sections between nodes representing intersections are connected by directed links l (lowercase L). More specifically, the DRM is a directed graph in which a node n is set for each intersection and each node n is connected by a pair of directed links l in opposite directions. Therefore, in the case of a one-way road, only one-way directed links l connect the node n.

[0051] The DRM also includes road attribute information of the road corresponding to the directed link l. The road attribute information includes, for example, the following information 1 to information 6: Information 1: Road type information indicating whether the road is an ordinary road or a toll road Information 2: Average gradient of the road Information 3: Number of lanes on the road Information 4: Road width for each lane Information 5: Radius of curvature of the road Information 6: Regulated speed limit of the road (for example, legal speed limit)

[0052] Traffic information database 265 stores traffic information. The traffic information includes, for example, past traffic volume on roads. The traffic information may be provided by an information organization such as the Japan Road Traffic Information Center, or by other organizations.

[0053] [Configuration of User Terminal] The user terminal 3 includes a processing unit 31, a storage unit 32, and a communication unit 33. The processing unit 31, the storage unit 32, and the communication unit 33 are electrically connected to each other via a bus. The user terminal 3 is further connected to an input device 34 and a display device 35.

[0054] The processing unit 31 is a processing unit including a CPU and a RAM, and reads out a computer program stored in the storage unit 32 and performs various information processing operations in accordance with the computer program.

[0055] The storage unit 32 is an auxiliary storage device including a non-volatile memory such as an HDD and an SSD. The storage unit 32 stores computer programs and various parameters in the non-volatile memory. The computer programs and various parameters are stored in the storage unit 32 in a form that can be read from a recording medium via a reading device (not shown) provided in the user terminal 3. The computer programs and various parameters may also be stored in the storage unit 32 in a form that can be downloaded from another computer via the public communication network 5.

[0056] The communication unit 33 is a communication interface that communicates with the server 2 via the public communication network 5. The communication unit 33 transmits a request for evaluation information to the server 2 in response to a user operation. The communication unit 33 also receives the evaluation information transmitted from the server 2.

[0057] The input device 34 is an input device such as a mouse and keyboard, and is operated by a user of the user terminal. The display device 35 is a display device such as a display, and displays various information such as SAR images to the user. The input device 34 and the display device 35 may be integrated into one device, such as a touch panel.

[0058] 2 is a flowchart illustrating a series of processes executed by the control unit 21 of the information providing server 2. When the server 2 receives a request for evaluation information (user request) transmitted from, for example, the user terminal 3, the control unit 21 executes the following various processes based on the computer program 221 stored in the storage unit 22. The user request includes various information such as the geographical range and time range of the requested evaluation information, and parameters that the user values.

[0059] The control unit 21 may execute the various processes described below periodically, for example, without waiting for a request from the user terminal 3, or may execute the various processes when the administrator of the server 2 issues an instruction to execute the process via the input device 24.

[0060] First, the outline of the process will be explained. The control unit 21 sequentially executes the following five steps. The order of the steps may be reversed within a range consistent with each other, or the steps may be processed in parallel.

[0061] Step ST11: User request reception processing Step ST12: Displacement information generation processing Step ST13: Target region extraction processing Step ST14: Influence calculation processing Step ST15: Output processing

[0062] This series of processes is executed to narrow down the area where crustal movements that have a large impact on the transportation network are occurring from the wide area of ​​the earth's surface observed by SAR. For example, the user operating the user terminal 3 is a road management company, and in order to narrow down the wide area of ​​roads that the user manages to areas that particularly require monitoring or areas that require construction work such as reinforcement, the user obtains evaluation information including the degree of impact of each area from the server 2 operated by the investigation company. This allows the user to suitably select areas of the roads that the user manages to conduct a field investigation on, based on the evaluation information.

[0063] In other words, based on a user request received from the user terminal 3 (step ST11), the control unit 21 generates displacement information representing the amount of ground surface displacement based on the SAR image and DEM data (step ST12), and extracts target areas that may have an impact on the transportation network based on the DRM and the displacement information (step ST13).

[0064] Then, in order to further narrow down the target areas to areas that have a large impact on the transportation network, the control unit 21 calculates the impact degree of each target area based on the traffic information (step ST14). Finally, the control unit 21 outputs evaluation information including the impact degree to the user terminal 3 (step ST15). The impact degree is used, for example, as one of the evaluation parameters indicating whether the target area requires monitoring or repair.

[0065] Through the above series of processes, the user can identify areas of interest (i.e., areas with a high degree of impact) from a wide area of ​​the ground surface. In this way, the server 2 can appropriately evaluate ground surface displacements that have a large impact on people's lives (particularly the transportation network) based on SAR images. Each step will be described in detail below.

[0066] [User request reception process: step ST11] First, the control unit 21 receives a user request transmitted from the user terminal 3. The user request is request information related to the content of evaluation information requested by the user, and is appropriately set by the user operating the user terminal 3. A method for setting the user request will be specifically described below.

[0067] 3 shows an example of a screen displayed on the display device 35 of the user terminal 3. First, the processing unit 31 displays a setting screen 6 on the display device 35 based on a computer program stored in the storage unit 32. The setting screen 6 is a screen for setting the content of a user request to be transmitted to the server 2.

[0068] The setting screen 6 includes a map display section 61 and a setting display section 62. The map display section 61 may be, for example, a topographical map or an aerial photograph. The user sets the content of the user request by operating a cursor 612 on the setting screen 6 using the input device 34.

[0069] For example, the user uses zoom buttons 613 or the like to display an appropriate area on the map display section 61. Then, by dragging a cursor 612 on the map display section 61, the user sets a geographical range 611 of the map display section 61 for which evaluation information is requested. The user also sets the time range of the evaluation information by inputting dates in the input fields for start time 614 and end time 615.

[0070] The setting display unit 62 includes input fields 621, 622, 623, and 624 for inputting weighting factors for various parameters. The weighting factors are used when performing calculations taking weighting factors into account in the influence calculation step (step ST14) described below. The input field 621 is a field for inputting a weighting factor W1 for the rate of change, the input field 622 is a field for inputting a weighting factor W2 for the presence or absence of a detour, the input field 623 is a field for inputting a weighting factor W3 for the increased travel time, and the input field 624 is a field for inputting a weighting factor W4 for traffic volume.

[0071] After entering these information, the user clicks the save button 625, and a user request including the set geographical range 611, time range, and weighting factors W1 to W4 is transmitted from the user terminal 3 to the server 2 via the public communication network 5. When the user clicks the reset button 626, the set contents are changed to the initial values.

[0072] The communication unit 23 of the server 2 transfers the received user request to the control unit 21. When the user request is input, the control unit 21 starts the processing from step ST12 onwards.

[0073] [Displacement Information Generation Process: Step ST12] First, based on a user request, the control unit 21 reads SAR images from a plurality of time points from the SAR image database 261. Specifically, for a location corresponding to the user-requested geographical range 611, the control unit 21 reads SAR images from a plurality of time points within the user-requested temporal range. For example, the control unit 21 reads a first SAR image observed at a time point after the start time point 614 and closest to the start time point 614, and a second SAR image observed at a time point before the end time point 615 and closest to the end time point 615.

[0074] Next, the control unit 21 generates information representing the ground surface displacement by analyzing the SAR images from multiple points in time. Specifically, the control unit 21 obtains the displacement from the ground surface observed in the first SAR image to the ground surface observed in the second SAR image by differential interferometric SAR analysis (DInSAR) based on the phase difference between the first SAR image and the second SAR image.

[0075] If the displacement is such that the Earth's surface approaches an aircraft device (e.g., a satellite) equipped with a SAR, it is considered that there is an uplift of the Earth's surface. Conversely, if the displacement is such that the Earth's surface moves away from the aircraft device, it is considered that there is a subsidence of the Earth's surface. Since the displacement is obtained based on the distance between the SAR and the Earth's surface, if the SAR observes the Earth's surface from an oblique direction, the displacement includes not only a vertical displacement component but also a horizontal displacement component.

[0076] The control unit 21 then reads out the DEM data from the DEM database 262 and corrects the ground surface displacement acquired by the differential interferometric SAR analysis based on the DEM data to generate displacement information including the amount of ground surface displacement for each of the multiple points. Finally, the control unit 21 stores the generated displacement information in the displacement information database 263.

[0077] The control unit 21 may use various types of interferometric SAR time series analysis instead of differential interferometric SAR analysis. For example, the control unit 21 may acquire the ground surface displacement by PS-InSAR analysis (Persistent Scatterer InSAR) or SBAS analysis (Small Baseline Subset).

[0078] Here, PS-InSAR analysis is a time series analysis method that estimates ground surface displacement using only pixel values ​​of SAR images that include persistent scatterers (PS), which are targets with stable reflection phases. PSs are artificial structures such as buildings, for example. SBAS analysis is a time series analysis method that creates a large number of data pairs with short vertical baseline lengths and short observation intervals and estimates the amount of displacement between each observation.

[0079] [Target Area Extraction Process: Step ST13] Next, the control unit 21 extracts a target area for calculating the impact level based on the displacement information and the DRM. Specifically, the control unit 21 extracts a displacement area from the displacement information where the absolute value of the displacement amount of the ground surface displacement is equal to or greater than a predetermined first threshold value Th1. Here, the "absolute value" of the displacement amount of the ground surface displacement is used because it is believed that both a large positive value of the ground surface displacement (ground uplift) and a large negative value of the ground surface displacement (ground subsidence) in the negative direction can have an impact on people's lives. The "absolute value of the displacement amount" is obtained by observing the displacement amount over multiple periods and removing the observation error. The first threshold value Th1 may be set appropriately. For example, the first threshold value Th1 may be 10 mm.

[0080] When the amount of ground surface displacement is small, it is considered that such surface displacement will have almost no impact on people's lives, so areas with small displacement amounts are excluded from the calculation of the impact degree by threshold processing. This makes it possible to reduce the number of target areas for which the control unit 21 (described below) performs the impact degree calculation process, thereby reducing the burden on the control unit 21.

[0081] By overlaying the DRM on the displacement information D1, the amount of ground displacement can be expressed for each pixel. The displacement information D1 is, for example, image information, and the amount of ground displacement is expressed for each pixel. In this case, dark areas represent areas where the amount of ground displacement is large, and light areas represent areas where the amount of ground displacement is small. Figure 4 is a schematic diagram showing a state in which the DRM is overlayed on the displacement information D1. In the example of Figure 4, the magnitude of the amount of ground displacement is expressed by the density of hatching instead of the density of color. In Figure 4, areas with high hatching density represent areas where the amount of ground displacement is large, and areas with low hatching density represent areas where the amount of ground displacement is small.

[0082] The control unit 21 performs threshold processing on the displacement information D1 using a first threshold value Th1 to extract multiple displacement areas where the displacement amount is equal to or greater than the first threshold value Th1. For simplicity, only displacement areas A1, A2, and A3 are shown in Fig. 4. Next, the control unit 21 extracts, as target areas, areas through which roads pass from among the multiple displacement areas, based on the link data included in the DRM.

[0083] For example, a road B1 passes through displacement area A1. Therefore, the control unit 21 extracts displacement area A1 as target area A1. Furthermore, a road B2 passes through displacement area A2. Therefore, the control unit 21 extracts displacement area A2 as target area A2. In contrast, no road passes through displacement area A3. Therefore, the control unit 21 does not extract displacement area A3 as a target area.

[0084] In the case of a sediment disaster such as a landslide or a mudslide, if the disaster occurs, the sediment may flow out of the area where the ground surface displacement has occurred, which may affect the transportation network outside the area adjacent to the area. For this reason, the control unit 21 may extract, as a target area, an area adjacent to a road from among the multiple displacement areas based on the link data included in the DRM.

[0085] In this case, the target area may be extracted based on a second threshold value Th2 for determining whether the displacement area and a road are close to each other. For example, even if no road passes through the displacement area A3, the control unit 21 extracts the displacement area A3 as the target area A3 if the distance from the displacement area A3 to the nearest road B3 is within the second threshold value Th2. The second threshold value Th2 is, for example, 5 m, 10 m, 20 m, or 30 m.

[0086] As described above, it is possible to extract target areas including ground surface displacements that may affect the transportation network based on the displacement information and the DRM. The control unit 21 stores the extracted target areas in the storage unit 22.

[0087] [Influence Calculation Process: Step ST14] Next, the control unit 21 calculates the influence of each of the multiple target areas based on the traffic information for each target area. For example, information such as traffic volume for road A1 passing through target area A1 in Figure 4 is used as traffic information for target area A1. Information such as traffic volume for road A2 passing through target area A2 in Figure 4 is used as traffic information for target area A2. Information such as traffic volume for road B3 adjacent to target area A3 in Figure 4 is used as traffic information for target area A3.

[0088] The impact degree (hereinafter, referred to as "Y1" where appropriate) is an evaluation parameter that indicates the magnitude of the impact that ground surface displacement has on the transportation network. Specifically, the control unit 21 calculates a larger impact degree Y1 for each target area as the amount of ground surface displacement increases. Furthermore, the control unit 21 calculates a larger impact degree Y1 for each target area as the traffic volume for that target area (i.e., the traffic volume on roads passing through that target area or on roads close to that target area) increases.

[0089] 5 is a table illustrating the relationship between various parameters such as traffic information and the impact degree Y1. The parameters for calculating the impact degree Y1 include, for example, the rate of change X1, the presence or absence of a detour X2, the additional travel time when a road is closed X3, and the traffic volume X4. Prior to calculating the impact degree Y1, the control unit 21 calculates or acquires these parameters X1 to X4 for each target area.

[0090] The rate of change X1 is a parameter indicating the rate of ground displacement. The larger the amount of ground displacement, the larger the rate of change X1. For example, the rate of change X1 is the value obtained by dividing the maximum cumulative value P1 of the amount of ground displacement in the target area by the average value P2 of the absolute displacement (absolute value of the displacement) of all target areas, and multiplying this value by 100. The maximum cumulative value P1 of the amount of ground displacement in the target area is the value of the amount of ground displacement (also referred to as the "cumulative displacement") accumulated within a specified observation period in a specified target area. For example, if observation of target area A1 begins on February 1, 2023, and a displacement of 25 mm is measured on January 31, 2024, 25 mm is considered to be the maximum cumulative value P1 of the amount of ground displacement in target area A1. The average value P2 of the absolute displacement (absolute value of the displacement) of all target areas is the average value of the accumulated displacement in all target areas. For example, the cumulative displacement amounts for the target areas A1, A2, and A3 are measured, and the average of the measured cumulative displacement amounts is set to the average value P2 of the absolute displacement amounts (absolute values ​​of the displacement amounts) for all the target areas. Based on the displacement information, for example, the control unit 21 calculates the rate of change X1 for each target area using the following formula (1).

[0091] X1=P1 / P2×100...(1)

[0092] Instead of the rate of change X1, the absolute value of the amount of displacement of the ground surface displacement (specifically, its maximum cumulative value P1) may be used as it is as a parameter for calculating the degree of influence Y1.

[0093] The presence or absence of a detour X2 is a parameter that indicates whether, when a road passing through the target area (or a road adjacent to the target area) is blocked, it is possible to reach the destination from the starting point without passing through that road. For example, the control unit 21 determines whether or not a detour exists by performing a route analysis using a known traffic simulator, with the starting point of link data corresponding to a road included in the target area as the starting point and the end point of that link data as the destination. As a known traffic simulator, for example, network analysis using an Origin-Destination Matrix (OD table) may be used.

[0094] If there is a detour (X2=1), the control unit 21 calculates the travel time T1 when taking the road passing through the target area and the travel time T2 when taking the detour, and calculates the difference between these (T2-T1) as the increased travel time X3 when the road is blocked. The travel time is calculated using known route analysis.

[0095] When a road passing through the target area is blocked, if it is absolutely impossible to reach the destination by land, the control unit 21 determines that there is no detour (X2 = 0). In this case, there is a risk that an isolated village will be created beyond the blocked road.

[0096] Furthermore, even if there is a detour, if the travel time T2 via the detour is extremely longer than the travel time T1 via the original road, it may be evaluated as being essentially the same as if there were no detour, and it may be determined that there is no detour. For example, if the travel time T2 exceeds a predetermined multiple (e.g., 10 times) of the travel time T1, or if the additional travel time X3 exceeds a predetermined time (e.g., 2 hours), the control unit 21 may uniformly determine that there is no detour (X2 = 0) even if there actually is a detour.

[0097] The traffic volume X4 is a value based on past traffic volume. For example, the control unit 21 may calculate the average value of traffic volume in the target area A1 over the past year from the traffic information database 265 and use the average value as the traffic volume X4. Alternatively, the maximum value of traffic volume over the past year may be used as the traffic volume X4.

[0098] The traffic volume X4 may be a current predicted traffic volume simulated based on past traffic volumes. In this case, the control unit 21 predicts the current predicted traffic volume based on the past traffic volumes using a known traffic simulator.

[0099] Furthermore, traffic capacity X41 may be used instead of traffic volume X4. While traffic volume X4 is a value based on past traffic volume, traffic capacity X41 is a value calculated based on road design. Specifically, traffic capacity X41 means the maximum number of vehicles that can pass through a cross section within a certain period of time under specified conditions, and is calculated based on the number of lanes on the road, the legal speed limit, etc.

[0100] After calculating or acquiring these parameters X1 to X4, the control unit 21 calculates the influence degree Y1 of each target area based on these parameters X1 to X4 and the weighting factors W1 to W4 included in the user request. Specifically, as shown in the following equation (2), the control unit 21 multiplies each of the parameters X1 to X4 by the weighting factors W1 to W4, respectively, and then calculates the sum of these to calculate the influence degree Y1. If there is no detour, the increased travel time will have no value (N / A). Therefore, a constant such as a road blockage constant C1 is prepared, and if there is no detour, the constant is added as shown in the following equation (3).

[0101] [When there is a detour] Y1 = W1 x X1 + W2 x X2 + W3 x X3 + W4 x X4 ... (2) [When there is no detour] Y1 = W1 x X1 + W2 x X2 + C1 + W4 x X4 ... (3)

[0102] In the example of Fig. 5, the weighting factors are W1 = 10, W2 = -5, W3 = 1, and W4 = 5. These are just examples, and the weighting factors W1 to W4 can be set to appropriate values ​​by the user as shown in Fig. 3. The weighting factors W1, W3, and W4 are all positive values. As a result, the control unit 21 calculates the influence degree Y1 to be larger the larger the rate of change X1, the longer the increased travel time X3, and the greater the traffic volume X4.

[0103] In contrast, the weighting factor W2 for the presence or absence of a detour X2 is a negative value so that the degree of influence when there is no detour is calculated to be greater than when there is a detour. The road block constant C1 is, for example, 100. The road block constant C1 may be a default value stored in advance in the storage unit 22, or may be a value set appropriately by the user.

[0104] For the target area A1, the change rate X1 is 23.3%; the traffic volume X4 is 150 pcu / (h*100); there is no detour (X2=0); and there is no increased travel time (N / A). Therefore, the influence Y1 is calculated as "1083" using the above formula. Similarly, the control unit 21 calculates the influence Y1 for each of the other target areas A2 to A5. The control unit 21 then stores the calculated influence Y1 for each of the target areas A1 to A5 in the storage unit 22.

[0105] The control unit 21 further calculates the ranking (priority) of the influence degrees Y1 of the multiple target areas A1 to A5 based on the calculated influence degrees Y1. In the example of Figure 5, the influence degree Y1 of the target area A4 is the highest, and the influence degree Y1 of the target area A5 is the lowest. The control unit 21 also stores these priorities in the storage unit 22.

[0106] As described above, by taking into account not only ground displacement but also traffic information, it is possible to appropriately evaluate and extract ground displacement that has a significant impact on people's lives. For example, if we consider only ground displacement, the area with the largest displacement among the multiple target areas A1 to A5 is target area A2. However, because the traffic volume on the roads passing through target area A4 is greater than the traffic volume on the roads passing through target area A2, and because there are detours on the roads passing through target area A2 but not on the roads passing through target area A4, the calculated impact level for target area A4 (Y1 = 1154) is greater than the impact level for target area A2 (Y1 = 579).

[0107] [Output process: step ST15] Next, the control unit 21 outputs the evaluation information 7 including the impact Y1 and the priority to the user terminal 3. The control unit 21 reads out the impact Y1 and priority of each of the multiple target areas A1 to A5 from the storage unit 22, and generates the evaluation information 7 by overlaying the impact Y1 and the priority on appropriate map information.

[0108] 6 is a schematic diagram showing an example of the evaluation information 7. The evaluation information 7 includes map information 71 and an evaluation icon 72. The map information 71 is, for example, an image captured or drawn of the earth's surface including multiple target areas A1 to A5 as viewed from above, and may be, for example, an optical image (aerial photograph), an SAR image, or a topographical map captured by an optical satellite. The map information 71 may be an image in which displacement information is superimposed on an optical image or a topographical map.

[0109] The evaluation icons 72 are icons placed at points corresponding to each of the multiple target areas A1 to A5 in the map information 71, and indicate the degree of influence Y1 or the priority. In FIG. 6, the evaluation icons 72 indicate the priority with numbers. Note that the evaluation icons 72 may indicate the degree of influence Y1 with numbers, color depth, or icon size. When the evaluation icons 72 indicate the priority, the degree of influence Y1 may be displayed as a pop-up when the mouse cursor is hovered over the evaluation icon 72.

[0110] When the processing unit 31 of the user terminal 3 receives the evaluation information 7 transmitted from the server 2, it displays the evaluation information 7 on the display device 35. This allows the user to know which of the target areas A1 to A5 in the geographical range set in the user request are experiencing ground surface displacement. The user can also know which of the target areas A1 to A5 has a particularly large impact on the transportation network (for example, the target area A4 with the greatest impact).

[0111] Furthermore, for example, if the user places the mouse cursor over the evaluation icon 72 (icon displaying the number 1) indicating the target area A4, a pop-up will appear displaying the numerical value "1154" for the impact level Y1. In this way, the magnitude of the impact that ground displacement in the target area has on the transportation network can be visualized numerically, allowing the user to more easily narrow down the areas that particularly require monitoring from the set geographical range.

[0112] The control unit 21 may output the evaluation information 7 to a display device 25 connected to the server 2. In this case, the administrator of the server 2 may narrow down the areas that particularly require monitoring based on the evaluation information 7 and report the narrowed down areas to the user. Even in this configuration, it is possible to suitably extract ground surface displacements that have a large impact on people's lives.

[0113] Each process (each function) in the above-described embodiments is executed by a processing circuit (circuitry) including at least one processor. The circuitry may be configured with a circuit such as an integrated circuit that combines, in addition to the processor, at least one memory, various analog circuits, and various digital circuits. The memory stores program code that causes the processor to execute the function. The processor may execute the function according to the program code read from the memory, or may execute the function according to a logic circuit that is pre-designed to execute the function. The processor may be any of various processors suitable for computer control, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), or ASIC (Application Specific Integrated Circuit). Note that multiple physically separated processors may cooperate with each other to execute functions. For example, processors installed in multiple physically separated computers may cooperate with each other to execute functions via a network such as a LAN (Local Area Network), a WAN (Wide Area Network), or the Internet. The program may be installed into memory from an external server device or the like via a network, or may be distributed in a state stored on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a semiconductor memory, and then installed into memory from the recording medium.

[0114] The embodiments of the present disclosure may be realized by an apparatus, a system, a method, an integrated circuit, a computer program, or a non-transitory computer-readable recording medium, or any combination thereof. The recording medium may be either volatile or non-volatile. The apparatus may be composed of multiple individual devices. When composed of multiple individual devices, they may be arranged in a single housing or may be arranged separately in two or more separate housings.

[0115] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present disclosure is not limited to the above-described embodiments, but includes all modifications within the scope of equivalents to the configurations described in the claims.

[0116] REFERENCE SIGNS LIST 1 Information provision system 2 Information provision server 21 Control unit 22 Memory unit 221 Computer program 23 Communication unit 24 Input device 25 Display device 26 Database 261 SAR image database 262 DEM database 263 Displacement information database 264 Map database 265 Traffic information database 3 User terminal 31 Processing unit 32 Memory unit 33 Communication unit 34 Input device 35 Display device 4 SAR image server 5 Public communication network 6 Setting screen 61 Map display unit 611 Geographical range 612 Cursor 613 Zoom in / out button 614 Start time 615 End time 62 Setting display unit 621 Input field 622 Input field 623 Input field 624 Input field 625 Save button 626 Reset button 7 Rating information 71 Map information 72 Rating icon W1, W2, W3, W4 Weighting coefficient Th1 First threshold Th2 Second threshold D1 Displacement information A1, A2, A3, A4, A5 Target area A1, A2, A3 Displacement area B1, B2, B3 Road X1 Rate of change X2 Presence or absence of detour X3 Increased travel time X4 Traffic volume X41 Traffic capacity Y1 Degree of impact T1, T2 Travel time C1 Road closure constant P1 Maximum cumulative value of change P2 Average value of absolute change

Claims

1. An information processing device comprising: a control unit that calculates an impact level indicating the magnitude of the impact that the ground surface displacement has on a transportation network based on displacement information regarding ground surface displacement analyzed based on synthetic aperture radar images and traffic information regarding the area where the ground surface displacement has occurred.

2. The information processing device described in claim 1, wherein the control unit extracts at least one of the areas through which roads pass and areas adjacent to roads as target areas based on road map information and the displacement information, and calculates the influence of the target area based on the traffic information related to the target area.

3. The information processing device described in claim 2, wherein the control unit extracts a displacement area where the absolute value of the amount of displacement of the ground surface displacement is equal to or greater than a predetermined first threshold value based on the displacement information, and extracts at least one of an area through which a road passes and an area adjacent to a road from the displacement area as the target area based on the road map information.

4. An information processing device as described in claim 2 or claim 3, wherein the traffic information includes information regarding traffic volume on roads passing through or close to the target area, and the control unit calculates the impact level to be greater the greater the amount of displacement of the ground surface displacement when the traffic volume for multiple target areas is the same.

5. An information processing device as described in claim 2 or claim 3, wherein the traffic information includes information regarding traffic volume on roads passing through or close to the target area, and the control unit calculates the impact level to be greater the greater the traffic volume related to the target area when the amount of displacement of the ground surface displacement in multiple target areas is the same.

6. An information processing device as described in claim 2 or claim 3, wherein the traffic information includes information regarding the presence or absence of a detour route when a road passing through or adjacent to the target area is closed, and the control unit calculates the impact level to be greater when there is no detour route than when there is a detour route when the amount of ground surface displacement in multiple target areas is the same.

7. The information processing device described in claim 2 or claim 3, wherein the traffic information includes information regarding the presence or absence of a detour route when a road passing through or close to the target area is closed, and the increased travel time, which is the increased travel time when taking the detour route compared to taking the actual road, and wherein the control unit calculates the impact level to be greater the longer the increased travel time when the amount of displacement of the ground surface displacement in multiple target areas is the same and when there is a detour route.

8. An information processing device described in any one of claims 2 to 7, wherein the control unit outputs evaluation information including the degree of influence in multiple target areas to a display device connected to the information processing device or a user terminal communicating with the information processing device.

9. An information processing method comprising: a calculation step of calculating an impact level indicating the magnitude of the impact that the ground surface displacement has on a transportation network, based on displacement information regarding ground surface displacement analyzed based on synthetic aperture radar images and traffic information regarding the area where the ground surface displacement has occurred.

10. A computer program that causes a computer to function as an information processing device, the computer program causing the computer to execute a calculation step of calculating an impact level that indicates the magnitude of the impact that the ground surface displacement has on a transportation network, based on displacement information regarding ground surface displacement analyzed based on synthetic aperture radar images and traffic information regarding the area where the ground surface displacement has occurred.

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