River flow estimation system

Abstract

To provide a river flow rate estimation system capable of acquiring a river flow rate by using an image obtained by capturing an image of a river without calculating a flow velocity.SOLUTION: A river flow rate estimation system for estimating a flow rate of a river based on an observation image obtained by capturing an image of the river, includes flow regime simulation means and display control means. The flow regime simulation means calculates a river water level at each place by using a three-dimensional terrain model, and the display control means displays a drawn image while changing a viewpoint and a visual line direction. The river flow rate estimation system can estimate the flow rate of the river included in the observation image by comparing the observation image with the drawn image, while changing the flow rate to be input in the flow regime simulation means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for estimating the flow rate of a river, and more specifically to a river flow rate estimation system that can estimate the flow rate of a river based on an image obtained by photographing the river. [Background technology]

[0002] It is useful to know the amount of water flowing in a river (flow rate), and it is especially important to know the river flow rate when flooding due to heavy rain is predicted. For over 100 years, the basic method for measuring flow rate during floods has been float observation. This float observation method involves dropping a float into the river and observing the time it takes for the float to travel a certain distance to determine the flow rate, and then multiplying this flow rate by the cross-sectional area of ​​the river (the part through which water flows) to determine the flow rate. Furthermore, float observation requires at least five observers, which means it is very labor-intensive.

[0003] On the other hand, in cases where it is difficult to dispatch many observers, such as rivers in mountainous regions, river flow is generally measured using the cross-section measurement method. With this method, the river cross section is measured at intervals of several centimeters, which requires a minimum of two to three observers, and the time required for observation at one location is estimated to be 15 to 30 minutes. In other words, determining river flow using the cross-section measurement method requires a great deal of effort, just like float observation.

[0004] It is possible to measure the flow rate directly using measuring equipment without relying on float observations or cross-sectional measurement methods, but using measuring equipment during floods is dangerous, and even if the measuring equipment were permanently installed, there is a risk that it could be damaged or result in missing readings, so this is not a realistic method.

[0005] Therefore, in recent years, attempts have been made to install cameras or video cameras at noteworthy locations in rivers and grasp the river flow rate using the images or videos taken. For example, Patent Document 1 proposes a technology for grasping the river flow rate by acquiring images of the river at two or more times and performing PIV (Particle Image Velocimetry) analysis using these images. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-216010 Summary of the Invention [Problem to be solved by the invention]

[0007] Until now, the mainstream method for understanding river flow rate has been to first determine the flow velocity and then calculate the flow rate. For example, in float observation, the speed of the float is measured, and in Patent Document 1, PIV analysis is performed to determine the river flow rate, and then the river flow rate is calculated by multiplying the flow velocity by the cross-sectional area of ​​the river.

[0008] However, measuring the flow velocity of a river, as with float observation, requires a lot of effort and does not always provide an accurate flow velocity, and even if PIV analysis is performed as in Patent Document 1, it is still not always possible to obtain an accurate flow velocity depending on the image conditions. And if an accurate flow velocity cannot be obtained, it is naturally impossible to grasp the accurate river flow rate.

[0009] The object of the present invention is to solve the conventional problems, that is, to provide a river flow estimation system that can grasp the river flow rate by using images obtained by photographing a river, without calculating the flow velocity. [Means for solving the problem]

[0010] The present invention focuses on the point that the flow rate of a river contained in a photographed image can be estimated by adjusting the image of a flow simulation so that it resembles an image obtained by photographing the river, and is an invention based on an idea that has not been seen before.

[0011] The river flow estimation system of the present invention is a system that estimates the flow rate of a river based on observation images of the river, and is equipped with a flow simulation means and a display control means. The flow simulation means is a means for calculating the river water level at each location using a 3D topographical model, and the display control means is a means for displaying a rendered image (an image in which the river and the 3D topographical model are superimposed) while changing the viewpoint and line of sight. The display control means displays the rendered image according to the viewpoint and line of sight that are further set so that the river water level matches the river calculated by the flow simulation means. Furthermore, the flow simulation means calculates the river water at each position that corresponds to a river in the 3D topographical model when the river flow rate is set. Then, by changing the flow rate set in the flow simulation means and comparing the observed image with the rendered image, the flow rate of the river included in the observed image can be estimated.

[0012] The river flow rate estimation system of the present invention may further include a field of view adjustment means for adjusting the viewpoint and line of sight of the display control means so that the drawn image has a field of view that is substantially the same as (including the same as) the observed image.

[0013] The river flow rate estimation system of the present invention may further include a photographing parameter input means and a drawing parameter calculation means. The photographing parameter input means is a means for inputting the photographing position and photographing direction of the observed image, and the drawing parameter calculation means is a means for calculating the viewpoint and line of sight of the drawn image based on the photographing position and photographing direction input by the photographing parameter input means. In this case, the display control means displays the drawn image according to the viewpoint and line of sight direction calculated by the drawing parameter calculation means. [Effects of the Invention]

[0014] The river flow rate estimation system of the present invention has the following effects. (1) The flow rate can be determined simply by acquiring observation images. For example, by permanently installing a camera on-site, unmanned operation and labor saving can be achieved. As a result, observation costs can be reduced and observers are not placed in dangerous situations. (2) In addition, since the flow rate can be grasped simply by installing a camera on-site, it can be applied in a variety of locations. (3) Even if the angle of view of the camera installed on-site changes, it can be flexibly adapted by adjusting the image of the flow simulation. (4) Since there is no need to calculate the flow velocity, it is possible to avoid the inconvenience of calculating an inaccurate river flow rate due to an inaccurate flow velocity. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing the main configuration of a river flow rate estimation system according to the present invention; [Figure 2] (a) is a photograph showing an example of an observed image, and (b) is a model diagram showing an example of a drawn image. [Figure 3] FIG. 3 is a flowchart showing an example of the main processing flow of the river flow rate estimation system in the first embodiment. [Figure 4] FIG. 6 is a flowchart showing an example of a main processing flow of the river flow rate estimation system in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] An example of an embodiment of a river flow rate estimation system according to the present invention will be described with reference to the drawings.

[0017] 1 is a block diagram showing the main components of a river flow rate estimation system 100 of the present invention. As shown in this figure, the river flow rate estimation system 100 of the present invention is configured to include a flow condition simulation means 101 and a display control means 102, and can also be configured to include a field angle adjustment means 103, a photography specification input means 104, a drawing specification calculation means 105, an image acquisition means 106, a display means 107, an observed image storage means 108, and a 3D topographic model storage means 109.

[0018] The flow regime simulation means 101, display control means 102, angle of view adjustment means 103, photographing parameter input means 104, and drawing parameter calculation means 105 that constitute the river flow rate estimation system 100 of the present invention can be manufactured as dedicated units, or a general-purpose computer device can be used. This computer device includes a processor such as a CPU, memories such as ROM and RAM, and may further include input means such as a mouse and keyboard, and display means such as a display, and can be configured, for example, by a personal computer (PC) or a server.

[0019] The observation image storage means 108 and the 3D terrain model storage means 109 can be configured as a storage device of a general-purpose computer (for example, a PC), or can be configured as a database server. When configured as a database server, they can be placed on a local network (LAN: Local Area Network), or can be configured as a cloud server that stores data via the Internet.

[0020] Below, each of the main elements that make up the river flow rate estimation system 100 will be described in detail.

[0021] (Image acquisition means) The image acquisition means 106 acquires images (hereinafter referred to as "observation images") obtained by photographing the river as still images or videos, and can be obtained using a digital camera, digital video camera, smartphone, tablet PC, etc. Figure 2(a) shows an example of an observation image. When acquiring an observation image, the image can be taken using the image acquisition means 106 carried by the observer, or using the image acquisition means 106 of a so-called fixed camera permanently installed on site, or satellite images can also be used. The still images and videos acquired by the image acquisition means 106 are stored in the observation image storage means 108 (Figure 1). Note that the observation images taken by the image acquisition means 106 of the fixed camera may be transmitted via communication means and then stored in the observation image storage means 108.

[0022] (3D terrain model memorizer) The three-dimensional terrain model storage means 109 is a means for storing a three-dimensional terrain model (hereinafter referred to as a "3D terrain model"). Here, a 3D terrain model is a representation of terrain, including features, using three-dimensional coordinates (i.e., constituent points), and is a terrain model typified by a DSM (Digital Surface Model) or a DEM (Digital Elevation Model). Typically, a 3D terrain model is composed of small areas obtained by dividing a target planar range. These small areas are also called meshes, and are formed by dividing the range into, for example, orthogonal grids, and each small area has a representative point. Because a three-dimensional point cloud (i.e., constituent point cloud) obtained by measurement is often random data (data that is irregularly arranged on a plane), geometric calculations are often performed to assign heights to the representative points of the small areas. This calculation method includes the TIN (Triangulated Irregular Network) method, which finds height using an irregular triangular network formed from random data, the Nearest Neighbor method, which uses the nearest laser measurement point, as well as the Inverse Distance Weighting (IDW) method, the Kriging method, and the averaging method.

[0023] (Flow simulation method) The flow regime simulation means 101 is a means for calculating, when an operator sets a desired river flow rate, to reproduce the river water level at each position based on the river flow rate and a 3D topographical model, and can also be a means for calculating the flow velocity in addition to the river water level. Specifically, it is a means for calculating the river water level at each position by having an electronic calculator (computer) execute calculation processing using a program. Note that the program used by the flow regime simulation means 101 can be any of a variety of conventionally used programs, including commercially available products.

[0024] (Display control means) The display control means 102 is a means for outputting an image in which a river and a 3D topographical model are superimposed (hereinafter referred to as a "drawn image") to a display means 107 such as a display. An example of the drawn image is shown in FIG. 2(b). The display control means 102 can also display the drawn image so that it matches the river water level calculated by the flow condition simulation means 101, and can further display the drawn image so that it is a bird's-eye view according to the set viewpoint and line of sight direction. This display control means 102 also causes a computer to execute processing using a conventional program, and can be implemented using the same program as the flow condition simulation means 101.

[0025] (Field of view adjustment means) As described above, the display control means 102 can display the drawn image so as to be a bird's-eye view according to the set viewpoint and line of sight direction. The angle-of-view adjustment means 103 is a means for setting the viewpoint and line of sight direction of the drawn image to be displayed by the display control means 102. This allows the display control means 102 to display the drawn image while appropriately changing the viewpoint and line of sight direction, and adjust the drawn image so as to become an image desired by the operator. To set the viewpoint and line of sight direction, for example, the operator can set the viewpoint and line of sight direction by operating the angle-of-view adjustment means 103 while checking the drawn image displayed on a display (display means 107). In this case, it is preferable to use a pointing device (such as a mouse, touch panel, pen tablet, touchpad, trackpad, or trackball), a keyboard, or the like as the angle-of-view adjustment means 103.

[0026] One of the technical features of the present invention is to estimate the river flow rate in an observation image by making the angle of view of the observation image and the drawn image approximately coincident (including coincidence). Here, the angle of view includes the range (size) and attitude (shape) of features (part of a 3D topographic model) included in the image (observation image or drawn image) and the shape of the river (particularly the river water level). In other words, if the range and attitude of the features and the shape of the river included in the observation image and the drawn image approximately coincide, the angle of view of the observation image and the drawn image will approximately coincide. Furthermore, making the angle of view of the observation image and the drawn image approximately coincident means that the river flow rate when the river water level related to the drawn image is calculated can be estimated to be the flow rate of the river included in the observation image.

[0027] The angle-of-view adjustment means 103 can be configured to set camera specifications (orientation elements) such as the camera's focal length, screen distance, deviation of the principal point position, and various distortions (radial distortion, asymmetric distortion, etc.) in addition to the viewpoint and line-of-sight direction of the drawn image. This allows the display control means 102 to display a drawn image using the river water level, 3D topographical model, viewpoint and line-of-sight direction, and camera specifications obtained by the flow condition simulation means 101 as given conditions, and to display a drawn image that is more closely matched to the angle of view of the observed image.

[0028] When the operator operates the angle-of-view adjusting means 103 while checking the drawn image displayed on the display (display means 107) so that the angles of view of the observed image and the drawn image approximately match, it is advisable to display the observed image on the display as well. For example, the observed image shown in Fig. 2(a) is displayed together with the drawn image shown in Fig. 2(b), and the set river flow rate is changed and the viewpoint and line of sight are changed so that the angle of view of the drawn image matches that of the observed image.

[0029] (Drawing parameter calculation means) As explained above, the angle of view of the drawn image and the observed image can be matched by adjusting the viewpoint and line of sight of the drawn image by the operator operating the angle-of-view adjustment means 103 (i.e., manually operating it), or the viewpoint and line of sight of the drawn image can be determined by calculation. In this case, the drawing parameter calculation means 105 calculates the viewpoint and line of sight of the drawn image based on the parameters (hereinafter referred to as "photography parameters") used when the observed image was captured. These photography parameters are input by the photography parameter input means 104. For example, the operator can input the photography parameters by operating a keyboard or the like, or the photography parameters can be transmitted via communication means when the image acquisition means 106 captures an image.

[0030] The imaging specifications include at least the imaging position and imaging direction, and may also include camera specifications. The imaging position is the three-dimensional coordinates (X, Y, Z) of the imaging position (lens center) of the image acquisition means 106, and can be measured using conventional positioning technologies such as the Global Navigation Satellite System (GNSS) or Total Station (TS). The imaging direction is the optical axis direction of the image acquisition means 106, and is a value determined by the tilt (yaw, pitch, roll) relative to three orthogonal axes (e.g., X, Y, Z axes), i.e., the rotation angle (ω, φ, κ) around each axis, and can be measured using an angular velocity sensor, a geomagnetic sensor, an IMU (Inertial Measurement Unit), etc.

[0031] In a case where the shooting parameters are input by the shooting parameter input means 104 and the drawing parameter calculation means 105 calculates the viewpoint and viewing direction of the drawing image based on the shooting parameters, the display control means 102 naturally displays the drawing image as a bird's-eye view according to the calculated viewpoint and viewing direction.

[0032] (Processing flow) The following describes in detail the main processing of the river flow rate estimation system 100. The explanation will be divided into a form in which the operator sets the viewpoint and line of sight of the drawn image by operating the angle of view adjustment means 103 (hereinafter referred to as "first form"), and a form in which the viewpoint and line of sight calculated by the drawing parameter calculation means 105 are set (hereinafter referred to as "second form").

[0033] Figure 3 is a flow chart showing an example of the main processing flow of the river flow estimation system 100 in the first form, where the central column shows the processing to be performed, the left column shows what is necessary for that processing, and the right column shows what results from that processing.

[0034] To estimate the flow rate of a river using the river flow rate estimation system 100 in the first embodiment, first, an observation image is acquired (Step 200 in Fig. 3) as shown in Fig. 3. As described above, the observation image can be acquired by image acquisition means 106 carried by an observer, or by image acquisition means 106 of a so-called fixed camera permanently installed on-site.

[0035] When the observation image is acquired, the river flow rate is set by the operator (Step 211 in Fig. 3 ).Then, the flow condition simulation means 101 calculates the river water level at each position based on the set river flow rate and the 3D topographic model read from the 3D topographic model storage means 109 (Step 212 in Fig. 3 ).

[0036] Once the river water level has been calculated, the operator sets the viewpoint and line of sight (Step 213 in FIG. 3 ), and the display control means 102 outputs the drawn image to the display means 107 (Step 214 in FIG. 3 ). Once the drawn image is displayed, the operator compares the drawn image with the observed image (Step 215 in FIG. 3 ). If the range and orientation of the features (i.e., the background) within the angle of view do not approximately match (including whether they do) (No in Step 215 in FIG. 3 ), the operator changes the viewpoint and line of sight (Step 213 in FIG. 3 ), displays the drawn image (Step 214 in FIG. 3 ), and compares the drawn image with the observed image again (Step 215 in FIG. 3 ). On the other hand, if the range and orientation of the features within the angle of view are approximately matched (Yes in Step 215 in FIG. 3 ), the operator compares the river water level within the angle of view of the drawn image with the angle of view of the observed image (Step 216 in FIG. 3 ).

[0037] If the river water level does not approximately match within the angle of view (No in Step 216 in FIG. 3), the river flow rate is changed (Step 211 in FIG. 3) and the series of processes (Steps 212 to 216 in FIG. 3) are repeated again. However, in this case, there is no need to change the viewpoint or line of sight. On the other hand, if the river water level within the angle of view approximately matches (Yes in Step 216 in FIG. 3), the river flow rate when the river water level in the drawn image was calculated is determined to be the flow rate of the river included in the observed image (Step 217 in FIG. 3).

[0038] Figure 4 is a flow chart showing an example of the main processing flow of the river flow estimation system 100 in the second form, where the central column shows the processing to be performed, the left column shows what is necessary for that processing, and the right column shows what results from that processing.

[0039] To estimate the flow rate of a river using the river flow rate estimation system 100 in the second embodiment, first, an observation image is acquired (Step 200 in Fig. 4) as shown in Fig. 4. As described above, the observation image can be acquired by image acquisition means 106 carried by an observer, or by image acquisition means 106 of a so-called fixed camera permanently installed on-site.

[0040] When an observed image is acquired, the operator inputs the photographing specifications (Step 221 in FIG. 4). Then, the rendering specifications calculation means 105 calculates the viewpoint and line of sight direction of the rendered image based on the photographing specifications (Step 222 in FIG. 4).

[0041] After calculating the viewpoint and viewing direction of the drawn image, the river flow rate input by the operator is set (Step 223 in Fig. 4). After the river flow rate is set, the flow condition simulation means 101 calculates the river water level at each position based on the set river flow rate and the 3D terrain model read from the 3D terrain model storage means 109 (Step 224 in Fig. 3).

[0042] Once the river water level is calculated, the display control means 102 outputs the drawn image to the display means 107 (Step 225 in FIG. 4). Then, the drawn image and the observed image are compared with each other, particularly with respect to the river water level, among the angles of view (Step 226 in FIG. 4).

[0043] If the angle of view (especially the river water level) of the drawn image and the observed image do not substantially match (No in Step 226 in FIG. 4), the river flow rate is changed (Step 223 in FIG. 4) and the series of processes (Steps 223 to 226 in FIG. 4) are repeated. On the other hand, if the angle of view of the drawn image and the observed image substantially match (Yes in Step 226 in FIG. 4), the river flow rate when the river water level of the drawn image was calculated is determined as the flow rate of the river included in the observed image (Step 227 in FIG. 4). [Industrial Applicability]

[0044] The river flow rate estimation system of the present invention is particularly useful for river administrators, including national and local governments. Considering that the present invention can quickly predict floods and other river-related water damage, and as a result, can protect many residents from disasters, the present invention can be said to be an invention that can be expected to not only be used industrially but also to make a great contribution to society. [Explanation of symbols]

[0045] 100 River flow rate estimation system of the present invention 101 Flow regime simulation method (of river flow estimation system) 102 Display control means (of river flow estimation system) 103 (River flow estimation system) angle of view adjustment means 104 (River flow estimation system) photography data input means 105 (River flow estimation system) drawing parameter calculation method 106 Image acquisition means (of river flow estimation systems) 107 Display means (of river flow estimation systems) 108 (River flow estimation system) observation image storage means 109 3D terrain model storage means (for river flow estimation systems)

Claims

1. A system for estimating the flow rate of a river based on observation images of the river, comprising: A flow simulation means for calculating the river water level at each location using a three-dimensional topographical model; a display control means for displaying a drawn image in which a river and a three-dimensional topographical model are superimposed while changing a viewpoint and a line of sight; the display control means displays the drawn image so as to correspond to the river water level calculated by the flow condition simulation means and in accordance with a set viewpoint and line of sight direction; the flow regime simulation means calculates the river water level at each position of the river in the three-dimensional topographical model when the flow rate of the river is set; The flow rate of the river included in the observed image can be estimated by comparing the observed image with the drawn image while changing the flow rate set in the flow regime simulation means. A river flow rate estimation system characterized by:

2. further comprising a view angle adjusting means for adjusting a viewpoint and a line of sight direction of the display control means so that the drawn image has the same or substantially the same view angle as the observed image; 2. The river flow rate estimation system according to claim 1.

3. an imaging parameter input means for inputting the imaging position and imaging direction of the observation image; a drawing parameter calculation means for calculating a viewpoint and a line of sight direction of the drawing image based on the photographing position and the photographing direction input by the photographing parameter input means, the display control means displays the drawn image according to the viewpoint and line of sight direction calculated by the drawing specification calculation means.

2. The river flow rate estimation system according to claim 1.

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