Information processing apparatus, information processing method, and program

Abstract

To provide an information processing device, an information processing method, and a program for suitably grasping a change in topography from a plurality of SAR images.SOLUTION: An information processor includes a data acquiring unit that acquires data of a plurality of SAR images obtained by surveying the ground surface of an observation target region from the sky by a synthetic aperture radar in a plurality of different periods, a coherence calculating unit that collates a first SAR image measured in a first period and a second SAR image measured in a second period later than the first period, and calculates a coherence for each position of corresponding images, and an immobile point setting unit that sets an immobile point serving as a reference for calculating a change in elevation of the observation target region based on the coherence.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an information processing device, an information processing method, and a program. [Background technology]

[0002] There is a demand to monitor changes in topography and reduce the risk of disasters, etc. There is also a surveying technology that uses a technology called Synthetic Aperture Radar (SAR).

[0003] According to Patent Document 1, the layer-by-layer subsidence measuring device acquires observation data on the vertical displacement of the ground surface and structures, as well as stratum data for specific stratums, and derives the amount of subsidence over time for each stratum of the ground from this data.

[0004] According to Patent Document 2, a dynamic monitoring system monitors an object whose movements are predicted, and calculates the displacement distribution of the object by comparing the difference between a reference displacement and the observed value at the wavelength of the synthetic aperture radar and the position of the measurement point.

[0005] According to Patent Document 3, the deformation degree determination system uses a synthetic aperture radar to measure the amount of displacement of an object on the ground surface, and determines the degree of deformation of the object using the amount of displacement and a deformation determination criterion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-183304 [Patent Document 2] Japanese Patent Application Publication No. 2019-215252 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-215248 Summary of the Invention [Problem to be solved by the invention]

[0007] However, if there is no reference point for determining the absolute elevation of the monitored area, it is difficult to determine the changes in the topography.

[0008] In view of the above-mentioned problems, an object of the present disclosure is to provide an information processing device and the like for appropriately grasping changes in topography from multiple SAR images. [Means for solving the problem]

[0009] The information processing device according to the present disclosure includes a data acquisition unit, a coherence calculation unit, and a fixed-point setting unit. The data acquisition unit acquires data on multiple SAR images obtained by surveying the surface of an observation target area from above using a synthetic aperture radar over multiple different time periods. The coherence calculation unit compares a first SAR image obtained during a first time period with a second SAR image obtained during a second time period after the first time period, and calculates the coherence for each position of the corresponding images. The fixed-point setting unit sets a fixed point that serves as a reference for calculating changes in elevation of the observation target area based on the coherence.

[0010] The information processing method according to the present disclosure causes a computer to perform the following process. The computer acquires data on multiple SAR images obtained by surveying the surface of an observation target area from above using a synthetic aperture radar over multiple different time periods. The computer compares a first SAR image acquired during a first time period with a second SAR image acquired during a second time period that follows the first time period, and calculates coherence for each position of the corresponding images. Based on the coherence, the computer sets a fixed point that serves as a reference for calculating changes in elevation of the observation target area.

[0011] A program according to the present disclosure causes a computer to execute the following information processing method. The computer acquires data on multiple SAR images obtained by surveying the surface of an observation target area from above using a synthetic aperture radar over multiple different time periods. The computer compares a first SAR image acquired during a first time period with a second SAR image acquired during a second time period that follows the first time period, and calculates the coherence for each position of the corresponding images. Based on the coherence, the computer sets a fixed point that serves as a reference for calculating changes in elevation of the observation target area. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide an information processing device, an information processing method, and a program for appropriately grasping changes in topography from multiple SAR images. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a first block diagram of an information processing device according to the present disclosure. [Figure 2] 1 is a first flowchart of an information processing method according to the present disclosure. [Figure 3] 1 is a schematic diagram illustrating the configuration of a surveying system according to the present disclosure. [Figure 4] FIG. 2 is a second block diagram of the information processing device according to the present disclosure. [Figure 5] 10 is a second flowchart of the information processing method according to the present disclosure. [Figure 6] FIG. 1 is a diagram showing the transition of data according to the present disclosure. [Figure 7] FIG. 10 is a third block diagram of an information processing device according to the present disclosure. [Figure 8] FIG. 10 is a diagram showing a process flow for setting a fixed point according to the present disclosure. [Figure 9] FIG. 10 is a diagram showing a flow of a process for calculating an elevation difference according to the present disclosure. [Figure 10] FIG. 2 is a block diagram illustrating an example of a hardware configuration of a computer. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential means for solving the problems. For clarity of explanation, the following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are assigned the same reference numerals, and duplicate explanations are omitted as necessary.

[0015] <First Embodiment> A first embodiment will be described below. FIG. 1 is a block diagram of an information processing device 10 according to the present disclosure. The information processing device 10 is used when observing changes in the topography of an observation target area. The information processing device 10 is, for example, a computer or a server. The information processing device 10 mainly includes a data acquisition unit 111, a coherence calculation unit 112, and a fixed point setting unit 113.

[0016] The data acquisition unit 111 acquires data on multiple SAR images obtained by surveying the surface of the observation target area from above. SAR images are images obtained by statistically processing data (SAR data) obtained by a synthetic aperture radar (SAR) mounted on an airborne vehicle. The airborne vehicle is, for example, an artificial satellite, an aircraft, or a drone. The airborne vehicle in the present disclosure is preferably an artificial satellite equipped with a synthetic aperture radar. This artificial satellite is also referred to as a radar satellite or a SAR satellite. The SAR image data acquired by the data acquisition unit 111 can also be referred to as SAR data. The multiple SAR images were each surveyed from the same position over multiple different time periods.

[0017] The coherence calculation unit 112 processes the SAR data acquired by the data acquisition unit 111 in accordance with the format of the SAR image. The coherence calculation unit 112 compares a first SAR image measured in a first period with a second SAR image measured in a second period after the first period, and calculates the coherence for each position of the corresponding images.

[0018] In the present disclosure, coherence refers to the degree of interference at corresponding positions in two SAR images. The coherence calculation unit 112 calculates the coherence of the two SAR images using well-known techniques. More specifically, the coherence calculation unit 112 compares the phases of corresponding positions in the two SAR images. In this way, the coherence calculation unit 112 calculates the coherence at the corresponding positions. When the corresponding positions in the two SAR images are perfectly aligned, the coherence is 1. As the difference between the two SAR images increases, the coherence approaches 0. It can be said that the closer the coherence is to 1, the better the interference of the SAR images.

[0019] Note that the corresponding positions in two SAR images are, for example, one pixel in the image data. In this case, the pixel in the SAR image corresponds to the resolution of the SAR image. The corresponding positions in two SAR images may also be statistically processed data of multiple adjacent pixels.

[0020] The fixed point setting unit 113 sets a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the above-described coherence calculated by the coherence calculation unit 112. More specifically, the fixed point setting unit 113 sets the fixed point from positions having coherence higher than a preset threshold, for example. Alternatively, the fixed point setting unit 113 may set a predetermined number of positions having the highest coherence as fixed points.

[0021] Next, processing executed by the information processing device 10 will be described with reference to Fig. 2. Fig. 2 is a first flowchart of the information processing method according to the present disclosure.

[0022] First, the data acquisition unit 111 acquires data of a plurality of SAR images obtained by surveying the earth's surface of an observation target area from above for a plurality of different periods using a synthetic aperture radar (step S11). The data acquisition unit 111 supplies the acquired SAR image data to the coherence calculation unit 112.

[0023] Next, the coherence calculation unit 112 compares the first SAR image measured in the first period with the second SAR image measured in a second period after the first period, and calculates the coherence for each position of the corresponding images (step S12). The coherence calculation unit 112 supplies data related to the calculated coherence to the fixed point setting unit 113.

[0024] Next, the fixed point setting unit 113 sets a fixed point that serves as a reference for calculating a change in the altitude of the observation target area, based on the coherence received from the coherence calculation unit 112 (step S13).

[0025] The above describes the information processing method executed by the information processing device 10. By using the above-mentioned method, the information processing device 10 sets a fixed point for the acquired SAR image. This allows a user of the information processing device 10 to conveniently grasp the elevation of the observation target area included in the acquired SAR image, using the fixed point set by the information processing device 10 as a reference.

[0026] The information processing device 10 may include a processor and a storage device as components not shown. The storage device included in the information processing device 10 includes a storage device including a nonvolatile memory such as a flash memory or an SSD (Solid State Drive). In this case, the storage device stores a computer program (hereinafter simply referred to as a program) for executing the above-described method. The processor also loads the computer program from the storage device into a buffer memory such as a DRAM (Dynamic Random Access Memory) and executes the program.

[0027] Each component of the information processing device 10 may be realized by dedicated hardware. Furthermore, some or all of the components may be realized by general-purpose or dedicated circuits, processors, etc., or a combination thereof. These may be configured by a single chip, or by multiple chips connected via a bus. Some or all of the components of each device may be realized by a combination of the above-mentioned circuits, etc., and programs. The processor may be a CPU (Central Processing Unit), GPU (Graphics Processing Unit), FPGA (Field-Programmable Gate Array), etc. Furthermore, at least some of the processing performed by the information processing device 10 may be provided as SaaS (Software as a Service). The description of the configurations described herein may also be applied to other devices or systems described below in this disclosure.

[0028] As described above, according to the present embodiment, it is possible to provide an information processing device, an information processing method, and a program for appropriately grasping changes in topography from a plurality of SAR images.

[0029] <Embodiment 2> Next, a second embodiment will be described. Fig. 3 is a schematic diagram of the configuration of a surveying system 1 according to the present disclosure. The surveying system 1 acquires an SAR image of an observation target area A10 and sets a fixed point. The surveying system 1 mainly includes a radar satellite 11, an antenna 12, a receiving device 13, a recording device 14, a display device 15, and an information processing device 20.

[0030] The radar satellite 11 generates SAR data by irradiating microwaves onto the Earth's surface from its onboard synthetic aperture radar and receiving the reflected waves. The SAR data includes information about the position of the observation target area A10. The SAR data also includes information about the position of the radar satellite 11. The radar satellite 11 transmits the generated SAR data to an antenna 12. The antenna 12 receives the SAR data from the radar satellite 11 and supplies the received SAR data to a receiving device 13.

[0031] The receiving device 13 performs processing such as demodulation on the SAR data received from the antenna 12 and supplies the data to the recording device 14. The recording device 14 has a recording medium such as an SSD (Solid State Drive), a hard disk, or a magnetic tape. The recording device 14 sequentially records the SAR data received from the receiving device 13 in a readable manner. The recording device 14 may be cloud storage. The recording device 14 is communicably connected to the information processing device 20 and supplies predetermined SAR data to the information processing device 20 in response to a request from the information processing device 20. The display device 15 displays the data processed by the information processing device 20 as an SAR image.

[0032] Next, the information processing device 20 will be described with reference to Fig. 4. Fig. 4 is a block diagram of the information processing device 20. The information processing device 20 has, as its main components, a data acquisition unit 111, a coherence calculation unit 112, a fixed point setting unit 113, a reference information acquisition unit 114, a storage unit 120, an operation reception unit 130, and a display control unit 140.

[0033] The data acquisition unit 111 of the information processing device 20 acquires data of multiple SAR images from the recording device 14. More specifically, the data acquisition unit 111 acquires data of a first SAR image measured in a first period and data of a second SAR image measured in a second period after the first period. The coherence calculation unit 112 compares the first SAR image with the second SAR image and calculates the coherence for each position of the corresponding images.

[0034] The fixed point setting unit 113 sets a fixed point that serves as a reference for calculating a change in the elevation of the observation target area from the coherence calculated by the coherence calculation unit 112. At this time, the fixed point setting unit 113 sets the fixed point by referring to the reference information received from the reference information acquisition unit 114.

[0035] The fixed point setting unit 113 may extract a range for setting a fixed point based on the reflection intensity contained in the SAR image, and set the fixed point from the extracted range. In other words, in this case, the fixed point setting unit 113 extracts a portion where the reflection intensity value is higher than a predetermined threshold. The portion where the reflection intensity value is higher than the predetermined threshold is, for example, an artificial object. This allows the information processing device 20 to set a fixed point from a portion where the topography changes relatively little.

[0036] The reference information is information used by the fixed-point setting unit 113 to set a fixed point. The reference information is, for example, information about the geology of the observation target area. The geological information includes information indicating the distribution of stones and strata that form the bedrock of the observation target area A10. In this case, the fixed-point setting unit 113 extracts a range in which to set a fixed point from the geological information included in the reference information. More specifically, the fixed-point setting unit 113 extracts, for example, a range of strata that are relatively unlikely to fluctuate as the range in which to set a fixed point. Then, the fixed-point setting unit 113 sets a fixed point from the extracted range. This allows the information processing device 20 to set a fixed point while excluding places where elevation fluctuations are likely to occur.

[0037] The reference information may be information about land attributes in the observation target area. In this case, the fixed-point setting unit 113 extracts a range for setting a fixed point based on the information about the land attributes included in the reference information, and sets the fixed point from the extracted range. The information about the land attributes is, for example, information about farmland, urban area, developed land, or road. The fixed-point setting unit 113 extracts a range associated with a preset attribute as the range for setting a fixed point. This allows the information processing device 20 to set a fixed point after previously extracting a location suitable for setting a fixed point.

[0038] The reference information may be information about the range of a radar shadow and a layover in the SAR image. In this case, the fixed point setting unit 113 sets a fixed point in a range outside the radar shadow and layover included in the reference information. In other words, the fixed point setting unit 113 extracts a range excluding the radar shadow and layover included in the reference information as a range for setting a fixed point, and sets a fixed point from the extracted range. This allows the information processing device 20 to set a fixed point excluding a range where elevation measurement becomes unstable.

[0039] In this disclosure, radar shadow refers to areas that cannot be surveyed because microwaves are blocked, such as the backside of a steep mountain slope, a valley, etc. Layover is a phenomenon in which the order of reception of reflected waves is reversed on a mountain slope whose gradient is steeper than the angle of incidence of the microwaves.

[0040] The reference information acquisition unit 114 acquires reference information for setting a fixed point. The information processing device 20 stores the reference information in the storage unit 120. The reference information acquisition unit 114 reads the reference information from the storage unit 120 and supplies the read reference information to the fixed point setting unit 113.

[0041] The storage unit 120 is a non-volatile memory such as a flash memory. The storage unit 120 stores at least reference information. The reference information is, for example, information about the geology of the observation target area. The reference information may also be information about the attributes of the land in the observation target area.

[0042] The reference information may also be information about the range of the radar shadow and layover in the SAR image. The reference information may also be information about the slope of the ground surface in the observation target area A10. In this case, the information processing device 20 may generate information about the range of the radar shadow and layover in the SAR image from information about the slope and the off-nadir angle of the SAR image.

[0043] The operation receiving unit 130 receives operations from a user who uses the information processing device 20. The operation receiving unit 130 receives predetermined information from an information input device such as a keyboard or switch through which the user inputs various instructions. The display control unit 140 controls image data of SAR images to be displayed on the display device 15.

[0044] Next, the processing executed by the information processing device 20 will be described with reference to Fig. 5. Fig. 5 is a second flowchart of the information processing method according to the present disclosure.

[0045] First, the data acquisition unit 111 acquires data of a plurality of SAR images including a first SAR image and a second SAR image from the recording device 14 (step S21). The data acquisition unit 111 supplies the acquired SAR image data to the coherence calculation unit 112.

[0046] Next, the coherence calculation unit 112 compares the first SAR image with the second SAR image and calculates the coherence for each position of the corresponding images (step S22). The coherence calculation unit 112 supplies data related to the calculated coherence to the fixed point setting unit 113.

[0047] Next, the reference information acquisition unit 114 acquires reference information corresponding to the observation target area A10 from the storage unit 120 (step S23). The reference information acquisition unit 114 supplies the acquired reference information to the fixed point setting unit 113.

[0048] Next, the fixed point setting unit 113 refers to the reference information and extracts a range in which to set a fixed point (step S24). Subsequently, the fixed point setting unit 113 sets a fixed point from the extracted range based on the coherence received from the coherence calculation unit 112 (step S25).

[0049] Next, the transition of data or information handled by the information processing device 20 will be described with reference to Fig. 6. Fig. 6 is a diagram showing the transition of data according to the present disclosure. Fig. 6 shows a first SAR image P1, a second SAR image P2, a coherence map D11, reference information R10, and fixed point data D12. In Fig. 6, each piece of data or information is associated with an arrow along the processing flow.

[0050] The upper part of Figure 6 shows a first SAR image P1 and a second SAR image P2. The first SAR image P1 is a SAR image of data measured during a first period. The second SAR image P2 is a SAR image of data measured during a second period that follows the first period. The first SAR image P1 and the second SAR image P2 were both generated by the radar satellite 11 irradiating the same area (e.g., observation target area A10) with microwaves from similar positions at similar angles of incidence.

[0051] Note that if the first SAR image P1 and the second SAR image P2 were measured close to each other, this is undesirable from the viewpoint of setting a fixed point, as this increases the number of candidate coincident points. Therefore, it is preferable that the first period and the second period be several weeks or more, and it is more preferable that there is a difference of several months to one year. When the information processing device 20 acquires the first SAR image P1 and the second SAR image P2, the coherence calculation unit 112 calculates the coherence from these two SAR images.

[0052] A coherence map D11 is shown in the middle of Fig. 6. The coherence map D11 is a schematic representation of coherence data calculated for each position of an image generated from the first SAR image P1 and the second SAR image P2. The coherence map D11 divides the SAR image into units for which coherence is calculated, and makes it possible to display the coherence for each unit.

[0053] The image units in the coherence map D11 are indicated by the X coordinate in the horizontal direction and the Y coordinate in the vertical direction, with the upper left corner as the reference point, and the position of each unit is indicated by the X coordinate in the horizontal direction and the Y coordinate in the vertical direction. For example, the coherence at the nth position in the X-axis direction and the mth position in the Y-axis direction is C(Xn, Ym). A partial enlarged view is shown on the left side of the coherence map D11. According to the partial enlarged view, C(Xn, Ym) is 0.425. In this way, the coherence map D11 displays coherence values ​​in a matrix. The coherence map D11 may also be displayed as a heat map in which numerical values ​​are converted into colors.

[0054] The reference information R10 shown on the right side of the coherence map D11 is reference information at a position corresponding to the first SAR image P1 and the second SAR image P2. The reference information R10 shown in FIG. 6 is information related to geology. The reference information R10 includes a first range R11 and a second range R12. The first range R11 is the left part of the image of the reference information R10 and is indicated by solid hatching. The second range R12 is the right part of the image of the reference information R10 and is indicated by dashed hatching. Here, for example, it is assumed that the first range R11 has harder geology than the second range R12. Therefore, the fixed point setting unit 113 sets a fixed point within the first range R11.

[0055] The fixed point data D12 is shown in the lower part of Fig. 6. The fixed point data D12 is obtained by superimposing the unit of the SAR image on the first range R11 extracted using the reference information. The fixed point setting unit 113 sets the image unit with a high coherence value from among the image units in the first range R11 as the fixed point.

[0056] The above describes the transition of data or information handled by the information processing device 20. In this way, the information processing device 20 sets a fixed point from SAR images measured over two different time periods, taking into account reference information. In this way, the information processing device 20 sets a fixed point that enables changes in the terrain to be understood. Therefore, according to this embodiment, it is possible to provide an information processing device, information processing method, and program for appropriately understanding changes in the terrain from multiple SAR images.

[0057] The information processing device 20 may store a plurality of different types of reference information and use these plurality of pieces of reference information to extract the setting of the fixed point. Alternatively, the information processing device 20 may select and use reference information suitable for setting the fixed point from the plurality of types of reference information as appropriate, depending on the position of the observation target area A10.

[0058] <Third Embodiment> Next, a third embodiment will be described. Fig. 7 is a block diagram of an information processing device 30. The information processing device 30 shown in Fig. 7 further includes an altitude calculation unit 115 in addition to the configuration of the information processing device 20 described above.

[0059] The altitude calculation unit 115 performs interference processing on two different SAR images to calculate the relative altitude. More specifically, the altitude calculation unit 115 calculates the primary altitude for the first period from a third SAR image and a fourth SAR image different from the third SAR image, each measured at a different time during a first period. The altitude calculation unit 115 also calculates the primary altitude for the second period from a fifth SAR image and a sixth SAR image different from the fifth SAR image, each measured at a different time during a second period.

[0060] The primary elevation includes information indicating the spatial relative elevation in the SAR image. However, the absolute elevation cannot be determined from the primary elevation. Therefore, information on a fixed reference point is required to calculate the difference in elevation between the primary elevation at the first time and the primary elevation at the second time.

[0061] In this case, the elevation calculation unit 115 calculates the elevation difference between the primary elevation in the first period and the primary elevation in the second period using the fixed point set by the fixed point setting unit 113. This allows the information processing device 30 to suitably calculate the change in topography when comparing the first period with the second period.

[0062] The coherence calculation unit 112 of the information processing device 30 compares any SAR image in the first period with any SAR image in the second period to calculate the coherence.

[0063] The fixed point setting unit 113 of the information processing device 30 sets a fixed point from the coherence calculated by the coherence calculation unit 112. In this case, the fixed point setting unit 113 may receive reference information from the reference information acquisition unit 114. The fixed point setting unit 113 may set a fixed point without receiving reference information from the reference information acquisition unit 114.

[0064] Next, processing executed by the information processing device 30 will be described with reference to Fig. 8. Fig. 8 is a diagram showing the flow of processing for setting a fixed point according to the present disclosure. Note that in the information processing device 30 shown in Fig. 8, the data acquisition unit 111 has already acquired the third SAR image P3, the fourth SAR image P4, the fifth SAR image P5, and the sixth SAR image P6.

[0065] The third SAR image P3 is a SAR image of data measured during a first period. The fourth SAR image P4 is a SAR image of data measured during the first period at a different timing than the third SAR image P3. There is a gap between the third SAR image P3 and the fourth SAR image P4, for example, of several days to several weeks. It is preferable that the difference between the timing at which the third SAR image P3 and the timing at which the fourth SAR image P4 are measured is short.

[0066] The fifth SAR image P5 is a SAR image of data measured during the second period. The sixth SAR image P6 is a SAR image of data measured during the second period at a different timing than the fifth SAR image P5. There is a gap between the fifth SAR image P5 and the sixth SAR image P6, for example, of several days to several weeks. It is preferable that the difference between the timing at which the fifth SAR image P5 and the timing at which the sixth SAR image P6 are measured is short.

[0067] In FIG. 8, the coherence calculation unit 112 generates a first coherence map at each point of the third SAR image P3 and the fifth SAR image P5 (step S31).

[0068] Next, the coherence calculation unit 112 generates a second coherence map at each point of the fourth SAR image and the sixth SAR image (step S32).

[0069] Next, the fixed point setting unit 113 sets a point with high coherence as a fixed point from the first coherence map and the second coherence map calculated by the coherence calculation unit 112 (step S33). Here, the fixed point setting unit 113 may set a point with high coherence as a fixed point by logically multiplying the first coherence map and the second coherence map. The fixed point setting unit 113 may set the fixed point by performing statistical processing on the first coherence map and the second coherence map. The statistical processing in this case may be, for example, calculation of an average value.

[0070] The process of setting a fixed point executed by the information processing device 30 has been described above. In the above description, the fixed point setting unit 113 sets a fixed point from two coherence maps. However, the fixed point setting unit 113 may set a fixed point from only the first coherence map, for example. The fixed point setting unit 113 may also set a fixed point from three or more coherence maps. In this case, the fixed point setting unit 113 may set a fixed point by calculating a variance or standard deviation as statistical processing. The information processing device 30 sets a fixed point from the coherence maps through the above-described process.

[0071] Next, a process of calculating an altitude difference performed by the information processing device 30 will be described with reference to Fig. 9. Fig. 9 is a diagram showing the flow of a process of calculating an altitude difference according to the present disclosure.

[0072] First, the altitude calculation unit 115 calculates the primary altitude in the first period from the third SAR image P3 and the fourth SAR image P4, which are SAR images measured at different times in the first period (step S41).

[0073] Next, the altitude calculation unit 115 calculates the primary altitude in the second period from the fifth SAR image P5 and the sixth SAR image P6, which are SAR images measured at different times in the second period (step S42).

[0074] Next, the altitude calculation unit 115 acquires the fixed point set by the fixed point setting unit 113 in the process shown in FIG. 8 (step S43).

[0075] Next, the altitude calculation unit 115 calculates the difference between the primary altitude in the first period and the primary altitude in the second period using the acquired fixed point position as a reference, thereby calculating the change in altitude (step S44). More specifically, the altitude calculation unit 115 calculates the change in altitude of the observation target area so that the change in the fixed point between the primary altitude in the first period and the primary altitude in the second period is minimized.

[0076] Although the embodiments have been described above, the information processing device 30 is not limited to the above-described functions or configuration. For example, the coherence calculation unit 112 may calculate coherence from the third SAR image P3 and the sixth SAR image P6. Similarly, the coherence calculation unit 112 may calculate coherence from the fourth SAR image P4 and the fifth SAR image P5. The information processing device 30 may perform geometric correction in addition to the above-described processing.

[0077] With the above-described configuration, the information processing device 30 can output changes in elevation so that changes in the ground surface of the observation target area can be grasped. Therefore, the information processing device 30 can provide the user with information such as the occurrence of embankments, changes in the amount of embankments, and changes in the amount of sediment deposited in rivers. Therefore, according to this embodiment, it is possible to provide an information processing device, information processing method, and program for appropriately grasping changes in topography from multiple SAR images.

[0078] <Example of hardware configuration> Hereinafter, an example will be described in which each functional configuration of an information processing device according to the present disclosure is realized by a combination of hardware and software.

[0079] FIG. 10 is a block diagram illustrating an example of a hardware configuration of a computer. The information processing device of the present disclosure can realize the above-described functions by a computer 500 including the hardware configuration shown in the figure. The computer 500 may be a portable computer such as a smartphone or tablet terminal, or a stationary computer such as a PC. The computer 500 may be a dedicated computer designed to realize each device, or may be a general-purpose computer. The computer 500 can realize desired functions by installing a predetermined application.

[0080] The computer 500 has a bus 502, a processor 504, a memory 506, a storage device 508, an input / output interface (I / F) 510, and a network interface (I / F) 512. The bus 502 is a data transmission path for the processor 504, the memory 506, the storage device 508, the input / output interface 510, and the network interface 512 to transmit and receive data to and from each other. However, the method for connecting the processor 504 and the like to each other is not limited to a bus connection.

[0081] The processor 504 is one of various processors such as a CPU, a GPU, an FPGA, etc. The memory 506 is a main storage device realized using a RAM (Random Access Memory) or the like.

[0082] The storage device 508 is an auxiliary storage device realized using a hard disk, an SSD, a memory card, a ROM (Read Only Memory), or the like. The storage device 508 stores programs for realizing desired functions. The processor 504 reads the programs into the memory 506 and executes them to realize the respective functional components of each device.

[0083] The input / output interface 510 is an interface for connecting the computer 500 to an input / output device. For example, an input device such as a keyboard and an output device such as a display device are connected to the input / output interface 510. The network interface 512 is an interface for connecting the computer 500 to a network.

[0084] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0085] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0086] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes. (Appendix 1) a data acquisition unit that acquires data of a plurality of SAR images obtained by surveying the surface of an observation target area from above over a plurality of different time periods using a synthetic aperture radar; a coherence calculation unit that compares a first SAR image measured during a first period with a second SAR image measured during a second period after the first period and calculates coherence for each position of the corresponding images; a fixed point setting unit that sets a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the coherence. Information processing device. (Appendix 1.1) the data acquisition unit acquires data of a plurality of SAR images obtained by surveying the observation target area from the same position by a SAR satellite; 10. The information processing device according to claim 1. (Appendix 2) a reference information acquisition unit that acquires information about the geology of the observation target area as reference information for setting the fixed point; the fixed point setting unit extracts a range in which the fixed point is to be set based on information about the geology included in the reference information, and sets the fixed point from the extracted range. 10. The information processing device according to claim 1. (Appendix 3) a reference information acquisition unit that acquires information about land attributes in the observation target area as reference information for setting the fixed point; the fixed point setting unit extracts a range in which the fixed point is to be set based on information on attributes of the land included in the reference information, and sets the fixed point from the extracted range. 10. The information processing device according to claim 1. (Appendix 4) the fixed point setting unit extracts a range in which the fixed point is to be set based on the reflection intensities included in the first SAR image and the second SAR image, and sets the fixed point from the extracted range. 10. The information processing device according to claim 1. (Appendix 5) a reference information acquisition unit that acquires information about a radar shadow and a layover range in the first SAR image and the second SAR image as reference information for setting the fixed point; the fixed point setting unit sets the fixed point in a range outside the radar shadow and the layover included in the reference information. 10. The information processing device according to claim 1. (Appendix 6) further comprising an elevation calculation unit that performs interference processing on two different SAR images to calculate relative elevation; The altitude calculation unit determining a primary elevation during the first period from a third SAR image and a fourth SAR image different from the third SAR image, each of which is measured at a different time during the first period; determining the primary elevation during the second period from a fifth SAR image and a sixth SAR image different from the fifth SAR image, which are respectively measured at different times during the second period; the coherence calculation unit compares any SAR image in the first time period with any SAR image in the second time period to calculate the coherence; the fixed point setting unit sets the fixed point based on the coherence; the elevation calculation unit calculates an elevation difference between the primary elevation in the first period and the primary elevation in the second period based on the fixed point; 6. The information processing device according to any one of Supplementary Notes 1 to 5. (Appendix 7) The coherence calculation unit calculates the coherence as calculating a first coherence map at each point of the third SAR image and the fifth SAR image; calculating a second coherence map at each point of the fourth SAR image and the sixth SAR image; the fixed point setting unit sets a point having high coherence from the first coherence map and the second coherence map as the fixed point; 7. The information processing device according to claim 6. (Appendix 8) the elevation calculation unit calculates a change in elevation of the observation target area so that a change in the fixed point between the primary elevation in the first period and the primary elevation in the second period is minimized. 7. The information processing device according to claim 6. (Appendix 9) The computer The synthetic aperture radar (SAR) acquires multiple SAR image data from the air, measuring the surface of the target area over multiple different time periods. comparing a first SAR image acquired during a first period with a second SAR image acquired during a second period after the first period, and calculating coherence for each position of the corresponding images; setting a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the coherence; Information processing methods. (Appendix 10) The synthetic aperture radar (SAR) acquires multiple SAR image data from the air, measuring the surface of the target area over multiple different time periods. comparing a first SAR image acquired during a first period with a second SAR image acquired during a second period after the first period, and calculating coherence for each position of the corresponding images; setting a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the coherence; Making a computer execute an information processing method program.

[0087] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 9 and 10 in the same dependency relationship as Supplementary Notes 2 to 8. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0088] 1. Surveying System 10. Information processing equipment 11 radar satellite 12 Antenna 13 Receiving device 14 Recording Devices 15 Display device 20 Information processing equipment 30 Information processing equipment 111 Data Acquisition Unit 112 Coherence calculation unit 113 Fixed point setting section 114 Reference information acquisition unit 115 Elevation calculation section 120 Storage section 130 Operation reception unit 140 Display control unit 500 computers 502 Bus 504 processor 506 memory 508 Storage Devices 510 Input / Output I / F 512 Network I / F A10 Observation area D11 Coherence Map D12 Fixed point data P1 First SAR image P2 Second SAR image P3 Third SAR image P4 4th SAR image P5 5th SAR image P6 6th SAR image R10 Reference Information

Claims

1. a data acquisition unit that acquires data of a plurality of SAR images obtained by surveying the earth's surface of an observation target area from above over a plurality of different time periods using a synthetic aperture radar; a coherence calculation unit that compares a first SAR image measured during a first period with a second SAR image measured during a second period after the first period and calculates coherence for each position of the corresponding images; a fixed point setting unit that sets a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the coherence. Information processing device.

2. a reference information acquisition unit that acquires information about the geology of the observation target area as reference information for setting the fixed point; the fixed point setting unit extracts a range in which the fixed point is to be set based on information about the geology included in the reference information, and sets the fixed point from the extracted range. The information processing device according to claim 1 .

3. a reference information acquisition unit that acquires information about land attributes in the observation target area as reference information for setting the fixed point; the fixed point setting unit extracts a range in which the fixed point is to be set based on information on attributes of the land included in the reference information, and sets the fixed point from the extracted range. The information processing device according to claim 1 .

4. the fixed point setting unit extracts a range in which the fixed point is to be set based on reflection intensities included in the first SAR image and the second SAR image, and sets the fixed point from the extracted range. The information processing device according to claim 1 .

5. a reference information acquisition unit that acquires information about a radar shadow and a layover range in the first SAR image and the second SAR image as reference information for setting the fixed point; the fixed point setting unit sets the fixed point in a range outside the radar shadow and the layover included in the reference information. The information processing device according to claim 1 .

6. an elevation calculation unit that performs interference processing on two different SAR images to calculate a relative elevation; The altitude calculation unit determining a primary elevation during the first period from a third SAR image and a fourth SAR image different from the third SAR image, each of which is measured at a different time during the first period; determining the primary elevation during the second period from a fifth SAR image and a sixth SAR image different from the fifth SAR image, each of which is measured at a different time during the second period; the coherence calculation unit compares any SAR image in the first time period with any SAR image in the second time period to calculate the coherence; the fixed point setting unit sets the fixed point based on the coherence; the elevation calculation unit calculates an elevation difference between the primary elevation in the first period and the primary elevation in the second period based on the fixed point; The information processing device according to any one of claims 1 to 5.

7. The coherence calculation unit calculates the coherence as calculating a first coherence map at each point in the third SAR image and the fifth SAR image; calculating a second coherence map at each point of the fourth SAR image and the sixth SAR image; the fixed point setting unit sets a point having high coherence as the fixed point from the first coherence map and the second coherence map; The information processing device according to claim 6 .

8. the elevation calculation unit calculates a change in elevation of the observation target area so that a change in the fixed point between the primary elevation in the first period and the primary elevation in the second period is minimized. The information processing device according to claim 6 .

9. The computer A plurality of SAR image data are acquired by surveying the surface of the observation target area from above for a plurality of different periods using a synthetic aperture radar; comparing a first SAR image measured during a first period with a second SAR image measured during a second period after the first period to calculate coherence for each position of the corresponding images; setting a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the coherence; Information processing methods.

10. A plurality of SAR image data are acquired by surveying the surface of the observation target area from above for a plurality of different periods using a synthetic aperture radar; comparing a first SAR image measured during a first period with a second SAR image measured during a second period after the first period to calculate coherence for each position of the corresponding images; setting a fixed point that serves as a reference for calculating a change in elevation of the observation target area based on the coherence; Making a computer execute an information processing method program.

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