Virtual digital water gauge generation method and water level measurement method

Abstract

The invention relates to the field of water level measurement, and provides a virtual digital water gauge generation method and a water level measurement method in order to overcome the defects of traditional water level measurement, enrich water level measurement means and assist in improving water level measurement precision. Extracting and generating a vectorized virtual digital water gauge as a leveling rod; by means of a three-dimensional map engine, oblique photography data, video stream data and virtual digital water gauge data are fused and overlapped, a spatialized video stream is projected into a three-dimensional map scene, overlapping comparison of a real-time video water surface and a virtual digital water gauge scale in the same three-dimensional scene is achieved, and the real-time video water surface and the virtual digital water gauge scale are displayed in a three-dimensional visualization mode. The water level of the water body in the target monitoring area is measured, and the measurement applicability and accuracy are higher.

Description

Technical Field

[0001] The present invention relates to the field of water level measurement, and in particular to a method for generating a virtual digital water gauge and a water level measurement method. Background Art

[0002] With the rapid development of information technology, water level monitoring based on video images, as an extension and supplement to conventional water level monitoring, has begun to be widely used in water level measurement. The industry generally uses two methods for water level measurement: "video + visual inspection" and "video + automatic recognition".

[0003] Whether using "video + visual inspection" or "video + automatic recognition", first of all, a reference level gauge for water level measurement must be obtained, and the accuracy of the level gauge will seriously affect the accuracy of water level measurement. There are mainly the following two ways to obtain the level gauge: One is to obtain it through detection and recognition, which is mainly applied to the scenario where physical water gauges are marked on the site in the monitored area of existing water gauges. Through image processing, image segmentation and other operations, the scales and numbers of the marked physical water gauges are detected and recognized; the other is to generate it by implanting or accessing the computer background algorithm of the front-end device. First, select obvious feature point markers for the images collected by the video, and calculate parameters such as the coordinate position and spatial geometric dimensions of the markers in the picture; perform perspective transformation on the reference object to obtain the forward and inverse perspective matrices; according to the actual spatial distance of the pre-entered reference object, divide it by the pixel distance in the picture to obtain the scale of the electronic water gauge; set the measurement range of the electronic water gauge to generate a virtual digital water gauge, and finally restore the virtual digital water gauge to the position in the picture according to the inverse perspective transformation matrix.

[0004] These systems and methods still have the following limitations and deficiencies in measurement accuracy, reliability and visual display:

[0005] (1) As the service life of the installed physical water gauge increases, and due to floating objects on the water surface and river erosion, the scales of the physical water gauge are worn and unclear to varying degrees, the scales are blocked or even washed away, resulting in the inability to identify the scales (including incomplete characters E) and numbers, thus affecting the accuracy of water level identification. In some special water level monitoring areas, due to factors such as terrain and traffic, the site does not have the conditions for manually installing physical water gauges.

[0006] (2) The method of generating a virtual digital water gauge by implanting an algorithm into the front-end device requires purchasing cameras with specified parameters or performance, and also requires custom development of virtual digital water gauges and recognition algorithms. For different monitoring areas and environmental conditions, due to the lack of sample data sets, the applicability and matching of the algorithms cannot be guaranteed, and the dependence on hardware devices and algorithms is high, and the cost is also very high.

[0007] (3) Whether the virtual digital water gauge is generated by implanting an algorithm through a front-end device or accessing a computer background algorithm, image processing technology is used to select a reference object and automatically generate it in the two-dimensional image coordinate system after converting the longitudinal coordinates of the image grid pixels into the actual distance in the physical world. The generated virtual digital water gauge has the following deficiencies: lack of spatial three-dimensional relationship, unable to cope with monitoring areas with large terrain undulations and complex backgrounds (such as high mountains and valleys), and not matching the terrain of the real environment. Image processing technology, especially when facing a monitoring water surface with a complex background, is easily interfered by factors such as image distortion and noise interference; the above disadvantages will cause a series of problems such as low accuracy of the generated level gauge and large deviation of the real position, thus affecting the real-time water level recognition accuracy. Summary of the Invention

[0008] In order to improve the water level measurement accuracy, the present application provides a method for generating a virtual digital water gauge and a water level measurement method.

[0009] The technical solution adopted by the present invention to solve the above problems is:

[0010] A method for generating a virtual digital water gauge, comprising:

[0011] Step 1: Obtain DEM data within the water level monitoring area;

[0012] Step 2: Extract the contour line data of the water level monitoring area according to the actual requirements of the DEM accuracy and the water level measurement accuracy, and create a virtual digital water gauge based on the contour lines.

[0013] Further, the interval value range of the contour lines is from 1 m to 0.1 m.

[0014] Further, the accuracy of the DEM data is not lower than 0.1 meter.

[0015] A water level measurement method, comprising:

[0016] Step 1: Obtain the oblique photography data within the water level monitoring area;

[0017] Step 2: Perform geographic coordinate conversion on the pixel coordinates of each frame of the water level monitoring video to realize the spatialization of the real-time video stream;

[0018] Step 3: Overlay the spatialized video stream data and the virtual digital water gauge on the basis of the oblique photography data; wherein, the virtual digital water gauge is obtained based on the method for generating a virtual digital water gauge;

[0019] Step 4: Obtain the water level line in the monitoring video and complete the water level measurement based on the virtual digital water gauge.

[0020] Further, the resolution of the oblique photography data is not lower than 0.2 meter.

[0021] Further, step 2 performs geographic coordinate conversion based on the timestamp, camera longitude, latitude, altitude, pitch angle, yaw angle, and side slip angle.

[0022] Further, step 3 is specifically as follows:

[0023] Step 31: Create a three-dimensional map scene and overlay oblique photography data in the three-dimensional map scene;

[0024] Step 32: Select and match feature points based on the oblique photography data and the spatialized video stream data to determine the position of the surveillance video in the three-dimensional map scene;

[0025] Step 33: Overlay the video stream data in the three-dimensional map scene based on the position determined in step 32;

[0026] Step 34: Overlay virtual digital water gauges in the three-dimensional map scene.

[0027] Further, before overlaying the oblique photography data and the spatialized video stream data, it also includes preprocessing the oblique photography data and the spatialized video stream data.

[0028] The beneficial effects of the present invention compared with the prior art are as follows: Based on high-precision contour data reflecting the real terrain, vectorized virtual digital water gauges are extracted and generated as leveling rods; with the help of a three-dimensional map engine, oblique photography data, video stream data, and virtual digital water gauge data are fused and overlaid, and the spatialized video stream is projected into the three-dimensional map scene to achieve the coincidence comparison of the video water surface and the virtual digital water gauge scale in the same three-dimensional scene, and the water level measurement of the target monitoring area is realized in a what-you-see-is-what-you-get three-dimensional visualization manner, with higher measurement accuracy.

[0029] The virtual digital water gauge can dynamically adjust the digital water gauge scale according to the monitoring range and display ratio, without the need for on-site construction and installation of physical water gauges, and there is no risk of being washed away or blocked, with stronger adaptability; since the virtual digital water gauge is generated from DEM data with high-precision measurement and is completely fitted to the real terrain surface, in the face of monitoring areas with large terrain undulations (such as high mountains and valleys), it can effectively avoid the influence of background factors such as terrain slope, complex image background, and pixel noise on the measurement accuracy, and the detection accuracy is higher.

[0030] Applying the spatialization of real-time video to water level measurement makes up for the deficiencies of traditional videos lacking position relationships and two-dimensional GIS being less vivid, and the visual experience is more intuitive and three-dimensional. Description of the Drawings

[0031] Figure 1 It is a flow chart of the water level measurement method. Detailed Embodiments

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] A method for generating a virtual digital water gauge, comprising:

[0034] Step 1: Obtain DEM data within the water level monitoring area through a drone, and the accuracy of the DEM data is not less than 0.1 meter;

[0035] Step 2: Extract the contour data of the water level monitoring area according to the actual requirements of the DEM accuracy and the water level measurement accuracy, and create a virtual digital water gauge based on the contour lines. According to the actual requirements of the DEM accuracy and the water level measurement accuracy, the interval value range of the contour lines is from 1 m to 0.1 m. In this embodiment, the interval of the contour lines is taken as 0.1 m.

[0036] Generating a virtual digital water gauge based on high-precision DEM data has the following advantages: First, there is no need for on-site construction and installation of physical water gauges, and there is no risk of being washed away or blocked; second, it matches the real environmental terrain. For special monitoring areas with a wide area and large terrain undulations (such as high mountains and valleys, etc.), it can truly reflect the relationship between the monitored target water surface and the background environment in a three-dimensional perspective, and the applicable environment is more extensive; third, the virtual digital water gauge generated through laser point cloud spatial measurement data has higher accuracy than the virtual digital water gauge generated by extracting and generating through the image processing technology of video stream frame feature points, thereby improving the accuracy of water level measurement and effectively avoiding the influence of factors such as image distortion and noise interference.

[0037] As Figure 1 shown, a water level measurement method, comprising:

[0038] Step 1: Obtain oblique photography data within the water level monitoring area, and the resolution of the oblique photography data is not less than 0.2 meter.

[0039] Step 2: Based on the three-dimensional map professional engine capabilities of WebGL technology, combined with the camera field of view angle, convert the pixel coordinates of each frame of the video into geographical coordinates through seven parameters: timestamp, camera longitude, latitude, altitude, pitch angle, yaw angle, and side deviation angle to realize the spatialization of the real-time video stream.

[0040] Step 3: Superimpose the spatialized video stream data and the virtual digital water gauge on the basis of the oblique photography data; wherein, the virtual digital water gauge is obtained based on the method for generating a virtual digital water gauge.

[0041] The specific steps of superimposing the spatialized video stream data and the virtual digital water gauge on the basis of the oblique photography data are as follows:

[0042] Step 31: Create a 3D map scene and overlay the oblique photography data in the 3D map scene;

[0043] Step 32: Select and match feature points based on the oblique photography data and the spatialized video stream data to determine the position of the surveillance video in the 3D map scene;

[0044] Step 33: Overlay the video stream data in the 3D map scene based on the position determined in Step 32;

[0045] Step 34: Overlay virtual digital water gauges in the 3D map scene.

[0046] Step 4: Obtain the water level line in the surveillance video and complete the water level measurement based on the virtual digital water gauge.

[0047] To improve the detection accuracy, before overlaying the oblique photography data and the spatialized video stream data, it also includes preprocessing the oblique photography data and the spatialized video stream data, including data format unification, noise removal, etc.

[0048] In the process of water level measurement, the present invention integrates high-fidelity oblique photography data, high-precision DEM data, and real-time surveillance video stream data to support fast and accurate water level measurement in a more precise, rich, and three-dimensional collaborative manner. A mapping model between pixel coordinates and geographic coordinates is established. Through seven parameters of timestamp, camera longitude, latitude, altitude, pitch angle, yaw angle, and roll angle, combined with the camera field of view, the pixel coordinates of each frame of the video are mutually converted with the geographic coordinates, making up for the deficiencies of traditional videos lacking position relationships, two-dimensional GIS being less vivid, and high three-dimensional modeling costs, and opening up a new mode of video + water level measurement.

Claims

1. Method for generating virtual digital water gauge, characterized in that, Including: Step 1: Obtain DEM data within the water level monitoring area; Step 2: Extract contour data of the water level monitoring area according to the actual requirements of DEM accuracy and water level measurement accuracy, and create virtual digital water gauges based on the contours.

2. The virtual digital water gauge generation method according to claim 1, wherein The interval value range of the contours is from 1m to 0.1m.

3. The virtual digital water gauge generation method according to claim 1 or 2, characterized in that, The accuracy of the DEM data is not less than 0.1 meter.

4. A water level measurement method, characterized in that, Including: Step 1: Obtain oblique photography data within the water level monitoring area; Step 2: Perform geographic coordinate conversion on the pixel coordinates of each frame in the water level monitoring video to realize the spatialization of the real-time video stream; Step 3: Overlay the spatialized video stream data and virtual digital water gauges on the basis of the oblique photography data; among them, the virtual digital water gauges are obtained based on the virtual digital water gauge generation method; Step 4: Obtain the water level line in the monitoring video and complete the water level measurement based on the virtual digital water gauges.

5. The water level measurement method according to claim 4, characterized in that, The resolution of the oblique photography data is not less than 0.2 meter.

6. The water level measurement method according to claim 4, characterized in that Step 2 performs geographic coordinate conversion based on the timestamp, camera longitude, latitude, altitude, pitch angle, yaw angle, and roll angle.

7. The water level measurement method according to claim 4, characterized in that, Step 3 is specifically as follows: Step 31: Create a 3D map scene and overlay the oblique photography data in the 3D map scene; Step 32: Select and match feature points based on the oblique photography data and the spatialized video stream data to determine the position of the monitoring video in the 3D map scene; Step 33: Overlay the video stream data in the 3D map scene based on the position determined in Step 32; Step 34: Overlay virtual digital water gauges in the 3D map scene.

8. The water level measurement method according to any one of claims 4-7, characterized in that, Before overlaying the oblique photography data and the spatialized video stream data, it also includes preprocessing the oblique photography data and the spatialized video stream data.

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