Water level measurement system, water level measurement device, water level measurement method, and program

Abstract

To provide a water level measuring technique robust to changes in the position and attitude of a measuring device for measuring a water level.SOLUTION: A water level measurement system includes point cloud acquisition means for acquiring a point cloud from a point cloud generation device that performs distance measurement on a water surface area and a land area to generate the point cloud, extraction means for extracting a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area from the point cloud, and water level calculation means for calculating a water level of the water surface area on the basis of the water surface point cloud and the land point cloud.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a water level measurement system, a water level measurement device, a water level measurement method, and a program. [Background technology]

[0002] Patent Document 1 discloses a device for measuring tide levels using a water level measurement sensor installed on a quay. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-338643 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, if the elevation of the water level measurement sensor itself changes due to crustal movement caused by an earthquake, for example, the tide level cannot be measured correctly thereafter.

[0005] An object of the present disclosure is to provide a water level measurement technique that is robust against changes in the position and orientation of a measurement device for measuring water level. [Means for solving the problem]

[0006] a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Including, A water level measurement system is provided.

[0007] a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Including, A water level measurement device is provided.

[0008] The computer, Acquire the point cloud from a point cloud generation device that measures the distance between the water surface area and the land area and generates the point cloud; extracting a water surface point cloud corresponding to the water surface region and a land point cloud corresponding to the land region from the point cloud; calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; A method for measuring water level is provided.

[0009] Computer, a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; To function as, Programs are offered. [Effects of the Invention]

[0010] According to the present disclosure, a water level measurement technique is provided that is robust against changes in the position and orientation of the point cloud generating device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of a water level measurement system. [Figure 2] 1 is a control flow of a water level measurement system. [Figure 3]FIG. 1 is a block diagram of a water level measurement system. [Figure 4] FIG. 1 is a bird's-eye view showing an example of installation of a LiDAR device. [Figure 5] This is an image of a point cloud output from a LiDAR device. [Figure 6] FIG. 1 is a side view of a water surface point cloud. [Figure 7] This is a histogram of the altitude of the water surface point cloud. [Figure 8] 1 is a control flow of a water level measuring device. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Summary of the Disclosure) FIG. 1 shows a block diagram of a water level measurement system 100 .

[0013] As shown in FIG. 1, the water level measurement system 100 includes a point cloud acquisition means 101, an extraction means 102, and a water level calculation means 103.

[0014] The point cloud acquisition means 101 acquires a point cloud from a point cloud generation device that generates a point cloud by measuring the distance between a water surface area and a land area.

[0015] The extraction means 102 extracts, from the point cloud acquired by the point cloud acquisition means 101, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area.

[0016] The water level calculation means 103 calculates the water level of the water surface area based on the water surface point cloud and the land point cloud.

[0017] FIG. 2 shows the control flow of the water level measurement system 100.

[0018] As shown in Fig. 2, first, the point cloud acquisition means 101 acquires a point cloud from a point cloud generation device that generates a point cloud by measuring the distance between a water surface area and a land area (S1101). Next, the extraction means 102 extracts a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area from the point cloud acquired by the point cloud acquisition means 101 (S1102). Next, the water level calculation means 103 calculates the water level of the water surface area based on the water surface point cloud and the land point cloud (S1103).

[0019] According to the water level measurement system 100 described above, a water level measurement technique that is robust against changes in the position and orientation of the point cloud generation device is realized.

[0020] (First embodiment) A first embodiment of the present disclosure will be described below.

[0021] FIG. 3 shows a schematic configuration diagram of a water level measurement system 1. As shown in FIG. 3, the water level measurement system 1 includes a water level measurement device 2, a plurality of LiDAR devices 3 (Light Detection And Ranging), and a plurality of mobile terminals 4. In this embodiment, the water level measurement system 1 includes three LiDAR devices 3. However, instead of this, the water level measurement system 1 may include only one LiDAR device 3. In this embodiment, the water level measurement system 1 includes two mobile terminals 4. However, instead of this, the water level measurement system 1 may include only one mobile terminal 4, or may not be provided with a mobile terminal 4.

[0022] Each LiDAR device 3 is a specific example of a point cloud generation device that measures distances and generates a point cloud. The point cloud generation device is a specific example of a measurement device for measuring water levels. The point cloud generation device may be a radar device (Radio Detection and Ranging) or a stereo camera instead of the LiDAR device 3. In this embodiment, the multiple LiDAR devices 3 include a LiDAR device 3A, a LiDAR device 3B, and a LiDAR device 3C.

[0023] Fig. 4 shows an example of installation of multiple LiDAR devices 3. As shown in Fig. 4, the multiple LiDAR devices 3 measure distances to a water surface area 7 including a water surface area 5, which is an area where the water surface or ocean surface extends, and a land area 6, which includes natural landforms and buildings on land. The multiple LiDAR devices 3 are typically installed in the land area 6. However, instead of this, the multiple LiDAR devices 3 may be installed in the water surface area 5.

[0024] Natural topography refers to the undulations of the earth's surface, and typically includes plains, plateaus, hills, mountains, ranges, and valleys. Structures include, for example, houses, shops, temples, shrines, and other buildings primarily made of wood and built for people to live or gather, as well as bridges, tunnels, dams, and other structures primarily made of concrete and built to facilitate daily life.

[0025] In the present embodiment, as an example, the LiDAR device 3A measures the distance to a water / land area 7 including a water surface area 5 and a land area 6. In contrast, the LiDAR devices 3B and 3C measure the distance only to the land area 6, and do not measure the distance to the water surface area 5. The land area 6 measured by the LiDAR device 3A and the land area 6 measured by the LiDAR device 3B at least partially overlap. Similarly, the land area 6 measured by the LiDAR device 3B and the land area 6 measured by the LiDAR device 3C at least partially overlap. The LiDAR devices 3B and 3C may be omitted.

[0026] The plurality of LiDAR devices 3 are connected to the water level measurement device 2 via wired communication or wireless communication so as to be able to perform two-way communication.

[0027] The multiple mobile terminals 4 are typically information terminals such as smartphones, tablet terminals, etc. The multiple mobile terminals 4 are connected to the water level measurement device 2 via wired communication or wireless communication so as to be able to communicate bidirectionally.

[0028] The water level measurement device 2 includes a processor 2a, a memory 2b, and a communication interface 2c. The processor 2a can access the memory 2b. The processor 2a communicates with multiple LiDAR devices 3 and multiple mobile terminals 4 via the communication interface 2c. The processor 2a reads and executes a program stored in the memory 2b. As a result, the processor 2a causes hardware such as the processor 2a to function as a point cloud acquisition unit 10, an extraction unit 11, a water level calculation unit 12, a flood risk assessment unit 13, and an alarm unit 14.

[0029] The processor 2a is typically a central processing unit (CPU), but may alternatively be a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0030] The memory 2b is typically realized by a ROM (Read Only Memory), a RAM (Random Access Memory), a HDD (Hard Disc Drive), or an SSD (Solid State Drive). The memory 2b stores programs executable by the processor 2a and various data required to execute the programs.

[0031] The point cloud acquisition unit 10 acquires a point cloud of the land and water area 7 from the LiDAR device 3A at predetermined intervals. The predetermined intervals are set to be suitable for monitoring fluctuations in the water level of the water surface area 5. The predetermined intervals are typically set between 30 seconds and 5 minutes. The point cloud acquisition unit 10 stores the acquired point clouds in chronological order in the memory 2b.

[0032] Here, an example of the purpose of use of the water level measurement system 1 will be given. As an example, the water level measurement system 1 is used to monitor fluctuations in the water level of the water surface area 5. For example, the water level measurement system 1 is used to monitor fluctuations in the tide level when an earthquake occurs or a typhoon arrives. Here, in this specification, the "tide level" can be replaced with "water level." The water level measurement system 1 is also used to monitor fluctuations in the water level of an earthen dam where a river is blocked by a landslide. The water level measurement system 1 is also used to monitor fluctuations in the water level of a river caused by an increase in the river's water level due to heavy rain. In this embodiment, as shown in FIG. 4, the water level measurement system 1 is used to monitor fluctuations in the tide level.

[0033] In Figure 5, the point cloud of the water / land area 7 acquired by the point cloud acquisition unit 10 is represented by dotted hatching. The water / land point cloud P, which is the point cloud of the water / land area 7, is made up of a water surface point cloud Q corresponding to the water surface area 5 and a land point cloud R corresponding to the land area 6. The extraction unit 11 extracts the water surface point cloud Q corresponding to the water surface area 5 and the land point cloud R corresponding to the land area 6 from the water / land point cloud P.

[0034] The extraction unit 11 may extract the land point cloud R from the land and water point cloud P by shape matching with the land area 6 modeled in advance, and may set the remaining land and water point cloud P as the water surface point cloud Q.

[0035] The extraction unit 11 may also extract the water surface point cloud Q and the land point cloud R from the water and land point cloud P according to the brightness of each point in the water and land point cloud P. For example, the brightness of the land point cloud R tends to be higher than the brightness of the water surface point cloud Q. Therefore, the extraction unit 11 can separate the water surface point cloud Q and the land point cloud R according to the brightness of each point in the water and land point cloud P.

[0036] The extraction unit 11 may also extract the water surface point cloud Q and the land point cloud R from the water / land point cloud P based on whether or not there is vibration at each point in the water / land point cloud P. For example, the water surface point cloud Q has the property of vibrating over time. In contrast, the land point cloud R does not have such a property. Therefore, the extraction unit 11 can distinguish between the water surface point cloud Q and the land point cloud R depending on whether or not there is vibration at each point in the water / land point cloud P.

[0037] The extraction unit 11 may also extract the water surface point cloud Q and the land point cloud R from the land and water point cloud P using PointNet.

[0038] The water level calculation unit 12 calculates the water level of the water surface region 5 based on the water surface point cloud Q and the land point cloud R.

[0039] In other words, if the position or attitude of the LiDAR device 3A changes from the time of installation, the water level of the water surface region 5 cannot be accurately measured based on the water surface point cloud Q. This is because the water surface point cloud Q is described in a LiDAR coordinate system specific to the LiDAR device 3A. In contrast, by using the land point cloud R, the water level calculation unit 12 can calculate the amount of change in the position and attitude of the LiDAR device 3A from the time of installation. Therefore, when calculating the water level of the water surface region 5 based on the water surface point cloud Q, the water level calculation unit 12 takes into account the amount of change in the position and attitude of the LiDAR device 3A from the time of installation, thereby making it possible to calculate the water level of the water surface region 5 robustly against changes in the position and attitude of the LiDAR device 3A. Hereinafter, the amount of change in the position and attitude of the LiDAR device 3A from the time of installation will also be simply referred to as the amount of change in the position and attitude of the LiDAR device 3A. Specifically, this is as follows.

[0040] First, the water level calculation unit 12 calculates the amount of change in the position and attitude of the LiDAR device 3A using the land point cloud R. That is, the water level calculation unit 12 calculates the amount of change in the position and attitude of the LiDAR device 3A by aligning the land point cloud R with the reference land point cloud stored in the memory 2b. For the alignment, for example, ICP (Iterative Closest Point) can be used.

[0041] As an example, the reference land point cloud is a land point cloud previously output from the LiDAR device 3A. The land point cloud previously output from the LiDAR device 3A typically refers to a land point cloud output from the LiDAR device 3A at the time the LiDAR device 3A was installed or immediately after the LiDAR device 3A was installed. In short, the land point cloud previously output from the LiDAR device 3A is a land point cloud output from the LiDAR device 3A at a timing that ensures that the position and attitude of the LiDAR device 3A have not changed since installation. Therefore, the water level calculation unit 12 can calculate the amount of change in the position and attitude of the LiDAR device 3A by aligning the land point cloud R with the reference land point cloud.

[0042] The reference land point cloud is, for example, a land point cloud output from a LiDAR device installed at a location different from the LiDAR device 3A. The LiDAR device installed at a location different from the LiDAR device 3A typically refers to the LiDAR device 3B. The water level calculation unit 12 can calculate the amount of change in the position and attitude of the LiDAR device 3A by comparing coordinate transformation information between the coordinate system of the LiDAR device 3A and the coordinate system of the reference land point cloud, which is obtained by aligning the latest land point cloud R output from the LiDAR device 3A with the reference land point cloud, with coordinate transformation information between the coordinate system of the LiDAR device 3A and the coordinate system of the reference land point cloud, which is obtained by aligning a land point cloud R previously output from the LiDAR device 3A with the reference land point cloud. As described above, the land point clouds output from the LiDAR device 3A and the land point clouds output from the LiDAR device 3B at least partially overlap. Furthermore, even if there is a change in the position or attitude of the LiDAR device 3A, if the change is due to local crustal movement or deformation of the installation facility itself where the LiDAR device 3A is installed, it is considered that the position or attitude of the LiDAR device 3B, which is sufficiently far away from the LiDAR device 3A, will not change. Therefore, the water level calculation unit 12 can calculate the amount of change in the position and attitude of the LiDAR device 3A by aligning the land point cloud R output from the LiDAR device 3A with the reference land point cloud.

[0043] In addition, when the LiDAR device 3C is installed farther away from the LiDAR device 3A than the LiDAR device 3B, and as described above, the point clouds output from the LiDAR device 3B and the point clouds output from the LiDAR device 3C partially overlap, even if the position and attitude of the LiDAR device 3B change together with the LiDAR device 3A, the water level calculation unit 12 can calculate the amount of change in the position and attitude of the LiDAR device 3A. This is because the amount of change in the position and attitude of the LiDAR device 3B can be calculated by aligning the point clouds output from the LiDAR device 3B with the point clouds output from the LiDAR device 3C. In this way, by using an alignment relay, i.e., the land point clouds output from multiple LiDAR devices installed sufficiently far from each other, the water level calculation unit 12 can calculate the amount of change in the position and attitude of the LiDAR device 3A even in the event of a wide-area crustal movement, such as simultaneous changes in the positions and attitudes of the LiDAR devices 3A and 3B.

[0044] Next, the water level calculation unit 12 calculates the vertical distance between the LiDAR device 3A and the water surface of the water surface area 5 based on the water surface point cloud Q.

[0045] Specifically, as an example, the water level calculation unit 12 selects an arbitrary point in the water surface point cloud Q, acquires the Z coordinate of the point in the LiDAR coordinate system, and converts the absolute value of the Z coordinate into the above-mentioned vertical distance.

[0046] Generally, the LiDAR device 3 is set so that the Z axis of the LiDAR coordinate system coincides with the vertical direction. Therefore, if the attitude of the LiDAR device 3A has not changed since installation, the water surface point cloud Q in the LiDAR coordinate system will be distributed widely along the XY plane in the LiDAR coordinate system. In this case, as described above, the water level calculation unit 12 can select any point in the water surface point cloud Q, obtain the Z coordinate of that point in the LiDAR coordinate system, and convert the absolute value of the Z coordinate into the above-mentioned vertical distance.

[0047] In contrast, if the attitude of the LiDAR device 3A has changed since installation, the water surface point cloud Q in the LiDAR coordinate system will be distributed widely along a plane that is generally inclined with respect to the XY plane. In this case, the water level calculation unit 12 selects any point in the water surface point cloud Q, obtains the Z coordinate of that point in the LiDAR coordinate system, corrects the absolute value of that Z coordinate according to the amount of change in the attitude of the LiDAR device 3A, and converts it into the above-mentioned vertical distance.

[0048] As another example, the water level calculation unit 12 can identify a plane corresponding to the water surface based on the water surface point cloud Q, and convert the distance between the origin of the LiDAR coordinate system and the plane in a direction perpendicular to the plane into the vertical distance between the LiDAR device 3A and the water surface of the water surface region 5. In this case, even if the attitude of the LiDAR device 3A has changed from the attitude at the time of installation, the water level calculation unit 12 can calculate the vertical distance without any problem.

[0049] Here, as a method for identifying a plane corresponding to the water surface based on the water surface point cloud Q, multiple regression analysis or RANSAC (Random sample consensus) analysis of the water surface point cloud Q can be adopted. In addition, since the water surface point cloud Q fluctuates slightly in the vertical direction over time, the water level calculation unit 12 can identify the plane in the LiDAR coordinate system by repeatedly acquiring the water surface point cloud Q at a predetermined interval and arithmetically averaging the Z coordinates in the LiDAR coordinate system of the acquired multiple sets of water surface point clouds Q.

[0050] As shown in FIG. 6, the water surface point cloud Q is generated along the swell of the water surface. Therefore, the Z coordinate of the plane in the LiDAR coordinate system can be calculated by simply arithmetically averaging the Z coordinates of the water surface point cloud Q. Alternatively, for each point a constituting the water surface point cloud Q, a normal vector b at that point a is estimated, and multiple peak / valley points e constituting the swell peaks c and valleys d are extracted from the water surface point cloud Q based on the normal vector b. The Z coordinates of the extracted multiple peak / valley points e in the LiDAR coordinate system can be arithmetically averaged to calculate the Z coordinate of the plane in the LiDAR coordinate system. FIG. 7 shows a histogram of the Z coordinates of multiple peak / valley points e in the LiDAR coordinate system. The horizontal axis of FIG. 7 represents altitude, and the vertical axis represents frequency. As shown in FIG. 7, the multiple peak / valley points e can be assumed to form two separate peaks in the histogram. Therefore, the water level calculation unit 12 can calculate the Z coordinate of the plane in the LiDAR coordinate system by simply taking the arithmetic average of the Z coordinates of multiple peak and valley points e, or by using Gaussian process regression to extract multiple representative values ​​of the Z coordinates of multiple peak and valley points e and taking the arithmetic average of the multiple representative values.

[0051] The water level calculation unit 12 may also extract a floating object point cloud, which is a point cloud corresponding to floating objects floating on the water surface of the water surface region 5, from the water surface point cloud Q, obtain the Z coordinate of the extracted floating object point cloud in the LiDAR coordinate system, and convert the absolute value of the Z coordinate into the above-mentioned vertical distance. As described above, if the attitude of the LiDAR device 3A has changed from the attitude at the time of installation, the water level calculation unit 12 may obtain the Z coordinate of the floating object point cloud in the LiDAR coordinate system, correct the absolute value of the Z coordinate by the amount of tilt, and convert it into the above-mentioned vertical distance. Because floating objects vibrate vertically over time, the floating object point cloud is likely to be distributed in an elongated manner in the vertical direction. Therefore, the water level calculation unit 12 may obtain the barycentric coordinate of the floating object point cloud, obtain the Z coordinate of the barycentric coordinate in the LiDAR coordinate system, and convert the absolute value of the Z coordinate into the above-mentioned vertical distance. Floating objects are typically man-made objects such as buoys. However, floating objects may also be natural objects such as tree branches. The water level calculation unit 12 may typically use an object detection technology such as PointNet to extract floating object point clouds from the water surface point cloud Q. When calculating the above vertical distance using the floating object point clouds, it is also possible to perform clustering on point clouds with close Euclidean distances and calculate the vertical distance for each cluster. Furthermore, floating objects that are close to each other between processing frames may be considered to be the same floating object and tracked before calculating the vertical distance.

[0052] The water level calculation unit 12 then calculates the water level of the water surface region 5 based on the water surface point cloud Q and the land point cloud R. That is, the water level calculation unit 12 calculates the vertical distance between the water surface of the water surface region 5 and the LiDAR device 3A based on the water surface point cloud Q. The water level calculation unit 12 calculates the amount of change in the position and attitude of the LiDAR device 3A based on the land point cloud R. Then, the water level calculation unit 12 calculates the water level of the water surface region 5 based on the vertical distance of the LiDAR device 3A from the water level reference point at the time the LiDAR device 3A was installed, the vertical distance calculated based on the water surface point cloud Q, and the amount of change calculated based on the land point cloud R. For example, if the vertical distance of the LiDAR device 3A from the water level reference point at the time of installation is plus 25 meters, the vertical distance calculated based on the water surface point cloud Q is minus 45 meters, and the change in the vertical direction of the LiDAR device 3A calculated based on the land point cloud R is plus 10 meters, the water level of the water surface region 5 will be minus 10 meters as seen from the water level reference point. Note that plus means vertically upward, and minus means vertically downward.

[0053] The timing at which the amount of change in the position and attitude of the LiDAR device 3A calculated based on the land point cloud R is reflected in the water level of the water surface area 5 is arbitrary.

[0054] For example, the change in the vertical position of the LiDAR device 3A may be corrected by correcting the Z coordinate of each point of the water surface point cloud Q itself, or by correcting the vertical distance calculated based on the water surface point cloud Q, or by performing correction based on the change for the first time when the water level of the water surface area 5 is calculated.

[0055] Furthermore, regarding the amount of change in the attitude of the LiDAR device 3A, typically, the amount of change may be used to correct the three-dimensional coordinates of each point of the water surface point cloud Q itself, and correction using the amount of change may be performed when calculating the above-mentioned vertical distance based on the water surface point cloud Q.

[0056] Water level control points are typically electronic control points, triangulation points, or leveling points.

[0057] The flood risk assessment unit 13 assesses the flood risk based on the water level of the water surface area 5 calculated by the water level calculation unit 12 and the land point cloud R. That is, the flood risk assessment unit 13 detects local crustal movements in the land area 6 in real time based on the land point cloud R, and compares the elevation of the subsided area of ​​the land area 6 with the water level of the water surface area 5, thereby assessing the flood risk in that area.

[0058] Furthermore, the flood risk assessment unit 13 can predict the arrival time of a tsunami based on the water surface point cloud Q. For example, the water level calculation unit 12 divides the water surface area 5 into multiple areas and calculates the water level for each of the multiple divided areas at predetermined time intervals based on the water surface point cloud Q. The flood risk assessment unit 13 can predict the arrival time of a tsunami based on the fluctuations in water level for each area calculated by the water level calculation unit 12. The flood risk assessment unit 13 may also calculate the tsunami speed, tsunami height, and arrival time using a tsunami model simulated in advance. In other words, it is known that tsunami speed and tsunami height vary depending on the topography of the land area 6. For example, the tsunami speed can be calculated using the following formula: In the following formula, V is the tsunami speed, g is the gravitational acceleration, and h is the water depth. TIFF2026002158000002.tif6150Therefore, the flood risk assessment unit 13 can accurately assess flood risk by acquiring the land point cloud R in real time and using the acquired land point cloud R to amplify the tsunami and correct the tsunami speed.

[0059] The warning unit 14 issues a warning based on the flood risk assessment result by the flood risk assessment unit 13. Specifically, the flood risk assessment unit 13 typically assesses the flood risk on a level of 1 to 5, with level 1 representing the lowest flood risk and level 5 representing the highest flood risk. The warning unit 14 then issues a warning over a wide area of ​​the land and water area 7 according to the flood risk level output by the flood risk assessment unit 13. For example, the warning unit 14 may issue a warning via multiple mobile terminals 4, or may issue a warning using a disaster prevention radio.

[0060] The warning unit 14 may also generate evacuation routes based on the land point cloud R acquired in real time. For example, the warning unit 14 may generate evacuation routes that avoid areas where the risk of flooding is locally increased due to subsidence, or areas with damaged transportation infrastructure or collapsed buildings. For example, the warning unit 14 may also detect areas where the level of risk of flooding is locally low, such as high ground or high-rise buildings, based on the land point cloud R, and generate evacuation routes that guide people to those areas. The warning unit 14 may provide the generated evacuation routes to local residents via multiple mobile devices 4.

[0061] Furthermore, when the water level measurement system 1 is applied to monitoring the water level of an earth dam, the water level calculation unit 12 calculates the water level of the earth dam in real time. The warning unit 14 may provide the calculated water level to local residents via multiple mobile terminals 4. Furthermore, the warning unit 14 may identify areas that are at risk of being submerged if the earth dam collapses, based on the land point cloud R, and provide information about those areas to local residents via multiple mobile terminals 4.

[0062] Furthermore, when the water level measurement system 1 is applied to monitor rising water levels in a river, the water level calculation unit 12 calculates the water level of the river in real time. The warning unit 14 may provide the calculated water level to local residents via multiple mobile terminals 4. Furthermore, the flood risk assessment unit 13 may make detailed predictions of future river flow rate and flood risk based on precipitation forecast data acquired from an external device via the communication interface 2c and information on the catchment area detected based on the land point cloud R.

[0063] Next, the control flow of the water level measurement device 2 will be described with reference to Fig. 8. Fig. 8 shows the control flow of the water level measurement device 2.

[0064] First, the point cloud acquisition unit 10 acquires a point cloud from the LiDAR device 3A, which measures the distance between the water surface region 5 and the land region 6 and generates the point cloud (S100). Next, the extraction unit 11 extracts a water surface point cloud Q corresponding to the water surface region 5 and a land point cloud R corresponding to the land region 6 from the point cloud acquired by the point cloud acquisition unit 10 (S110). Next, the water level calculation unit 12 calculates the water level of the water surface region 5 based on the water surface point cloud Q and the land point cloud R (S120). Next, the flood risk assessment unit 13 evaluates the flood risk based on the water level of the water surface region 5 calculated by the water level calculation unit 12 and the land point cloud R (S130). Then, the warning unit 14 issues a warning based on the flood risk assessment result by the flood risk assessment unit 13 (S140).

[0065] The preferred embodiments of the present disclosure have been described above. The above embodiments have the following features.

[0066] That is, the water level measurement system 1 includes a point cloud acquisition unit 10 (point cloud acquisition means), an extraction unit 11 (extraction means), and a water level calculation unit 12 (water level calculation means). The point cloud acquisition unit 10 acquires a point cloud from a LiDAR device 3A (point cloud generation device) that measures the distance between a water surface area and a land area to generate the point cloud. The extraction unit 11 extracts a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area from the point cloud. The water level calculation unit 12 calculates the water level of the water surface area based on the water surface point cloud and the land point cloud. The above configuration realizes a water level measurement technology that is robust against changes in the position and attitude of the point cloud generation device.

[0067] The water level calculation unit 12 calculates the amount of change in the position and attitude of the LiDAR device 3A by aligning the land point cloud R with the reference land point cloud. The water level calculation unit 12 calculates the water level of the water surface region 5 based on the water surface point cloud Q and the amount of change. With the above configuration, by utilizing the land point cloud R, a water level measurement technology that is robust against changes in the position and attitude of the point cloud generation device is realized.

[0068] In addition, the reference land point cloud is, for example, a land point cloud previously output from the LiDAR device 3A. According to the above configuration, the reference land point cloud can be the land point cloud before the position or attitude of the LiDAR device 3A changes.

[0069] Moreover, the reference land point cloud is a land point cloud output from a LiDAR device 3B (point cloud generating device) installed at a location different from that of the LiDAR device 3A. According to the above configuration, the reference land point cloud can be a land point cloud that is separated from changes in the position and attitude of the LiDAR device 3A.

[0070] Furthermore, the water level calculation unit 12 divides the water surface area 5 into a plurality of areas and calculates the water level for each of the divided areas. With the above configuration, the tsunami speed of the tsunami in the water surface area 5 can be calculated.

[0071] Furthermore, the water level calculation unit 12 extracts a floating object point cloud as a point cloud corresponding to floating objects floating on the water surface from the water surface point cloud Q. The water level calculation unit 12 calculates the water level of the water surface region 5 based on the floating object point cloud and the land point cloud R. With the above configuration, the vertical distance between the LiDAR device 3 and the water surface of the water surface region 5 can be smoothly measured.

[0072] The water level measurement system 1 further includes a flood risk assessment unit 13 (flood risk assessment means) that assesses flood risk based on the water level calculated by the water level calculation unit 12 and the land point cloud R, and an alarm unit 14 (alert means) that issues an alarm based on the results of the flood risk assessment. The above configuration realizes a flood risk warning system that comprehensively captures water level fluctuations and crustal movements.

[0073] In the above example, the program can be stored and supplied to a computer using various types of non-transitory computer-readable media. Non-transitory computer-readable media include various types of tangible storage media. Non-transitory computer-readable media include, for example, magnetic recording media, magneto-optical recording media, CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories. Semiconductor memories include, for example, mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory). The program may also be supplied to a computer by various types of transient computer-readable media. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transient computer-readable media can be supplied to a computer via wired communication paths such as electrical wires and optical fibers, or wireless communication paths.

[0074] 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.

[0075] 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.

[0076] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes. (Appendix 1) a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Including, Water level measurement system. (Appendix 2) The water level calculation means Calculating the amount of change in position and attitude of the point cloud generating device by aligning the land point cloud with a reference land point cloud; calculating a water level of the water surface region based on the water surface point cloud and the amount of change; 1. A water level measurement system as described in Appendix 1. (Appendix 3) The reference land point cloud is a land point cloud previously output from the point cloud generation device. 1. A water level measurement system as described in Appendix 2. (Appendix 4) The reference land point cloud is a land point cloud output from a point cloud generation device installed at a location different from that of the point cloud generation device. 1. A water level measurement system as described in Appendix 2. (Appendix 5) The water level calculation means divides the water surface area into a plurality of areas and calculates the water level for each of the plurality of divided areas. 1. A water level measurement system as described in Appendix 1. (Appendix 6) The water level calculation means extracting a floating matter point cloud as a point cloud corresponding to floating matter floating on the water surface from the water surface point cloud; calculating the water level of the water surface area based on the floating object point cloud and the land point cloud; 1. A water level measurement system as described in Appendix 1. (Appendix 7) a flood risk assessment means for assessing flood risk based on the water level calculated by the water level calculation means and the land point cloud; an alarm means for issuing an alarm based on the result of the flood risk assessment; Further equipped with, 1. A water level measurement system as described in Appendix 1. (Appendix 8) a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Including, Water level measuring device. (Appendix 9) The computer, Acquire the point cloud from a point cloud generation device that measures the distance between the water surface area and the land area and generates the point cloud; extracting a water surface point cloud corresponding to the water surface region and a land point cloud corresponding to the land region from the point cloud; calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Water level measurement method. (Appendix 10) Computer, a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; To function as, program.

[0077] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 7 that are dependent on Supplementary Notes 1 may also be dependent on Supplementary Notes 8 to 10 in the same dependency relationship as Supplementary Notes 2 to 7. 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]

[0078] 1. Water level measurement system 2 Water level measuring device 2a processor 2b Memory 2c communication interface 3 LiDAR device 3A LiDAR device 3B LiDAR device 3C LiDAR device 4. Mobile devices 5 Water surface area 6 Land area 7 Aquatic domain 10 Point cloud acquisition section 11 Extraction part 12 Water level calculation section 13. Flood Risk Assessment Department 14 Alarm section P Water and land point group Q Water surface point cloud R Land Point Cloud point a b normal vector c mountain d valley e Sanya point

Claims

1. a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Including, Water level measurement system.

2. The water level calculation means Calculating the amount of change in position and attitude of the point cloud generating device by aligning the land point cloud with a reference land point cloud; calculating a water level of the water surface region based on the water surface point cloud and the amount of change; The water level measurement system of claim 1 .

3. The reference land point cloud is a land point cloud previously output from the point cloud generation device. The water level measurement system according to claim 2 .

4. The reference land point cloud is a land point cloud output from a point cloud generation device installed at a location different from that of the point cloud generation device. The water level measurement system according to claim 2 .

5. The water level calculation means divides the water surface area into a plurality of areas and calculates the water level for each of the plurality of divided areas. The water level measurement system of claim 1 .

6. The water level calculation means extracting a floating matter point cloud as a point cloud corresponding to floating matter floating on the water surface from the water surface point cloud; calculating the water level of the water surface area based on the floating object point cloud and the land point cloud; The water level measurement system of claim 1 .

7. a flood risk assessment means for assessing flood risk based on the water level calculated by the water level calculation means and the land point cloud; an alarm means for issuing an alarm based on the result of the flood risk assessment; Further equipped with, The water level measurement system of claim 1 .

8. a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Including, Water level measuring device.

9. The computer Acquire the point cloud from a point cloud generation device that measures the distance between the water surface area and the land area and generates the point cloud; extracting a water surface point cloud corresponding to the water surface region and a land point cloud corresponding to the land region from the point cloud; calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; Water level measurement method.

10. Computer, a point cloud acquisition means for acquiring a point cloud from a point cloud generation device that measures the distance between a water surface area and a land area and generates the point cloud; an extraction means for extracting, from the point cloud, a water surface point cloud corresponding to the water surface area and a land point cloud corresponding to the land area; a water level calculation means for calculating a water level of the water surface area based on the water surface point cloud and the land point cloud; To function as, program.

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