A method for reconstructing underwater terrain of river channel based on cross-section data

Abstract

A method for reconstructing underwater terrain of a river channel based on cross-sectional data comprises the following steps: S10: drawing the boundary of a dredging area; S20: extracting the range of upstream and downstream river sections of the dredging area; S30: extracting terrain data of a digital elevation model; S40: arranging sampling points; S50: calculating the elevation of sampling points; S60: reconstructing a digital elevation model. The present invention provides a method for reconstructing underwater terrain of a river channel based on cross-sectional data, which only encrypts sampling points of the dredged river section, simplifies data processing steps, improves calculation efficiency, and enhances the quality of digital elevation of underwater terrain of the river channel.

Description

Technical Field

[0001] The invention belongs to the technical field of river underwater terrain modeling, and in particular relates to a river underwater terrain reconstruction method based on cross-section data. Background Art

[0002] The rapid development of social economy has brought about negative impacts on the ecological environment that cannot be ignored. At the same time, it is accompanied by multiple infringements such as industrial and civilian drainage, resulting in serious silt deposition in some river sections, affecting the city’s flood control and drainage functions.

[0003] In recent years, the protection and management of river sections have been continuously strengthened, and underwater topographic surveys have been actively carried out. Through underwater topographic surveys, underwater topographic digital elevation models are constructed. Based on the comparative analysis of the two phases of underwater topographic digital elevation models, river channels with serious silt deposition can be found, which helps to carry out dredging work and reduce the pressure of urban flood control and drainage. After the dredging is completed, considering the measurement cost, generally only cross-sectional measurements are carried out on the dredged river sections. Therefore, the underwater topographic digital elevation model after dredging needs to be based on some new cross-sectional data to reconstruct the underwater topography of the river channel, so as to provide a scientific basis for the protection and management of river sections and construction projects within the scope of river section management in the later stage.

[0004] Based on some new cross-sectional data, the underwater topography of the river is reconstructed. The most important thing is to encrypt the sampling points of the dredged river section according to the new cross-sectional data and the upstream and downstream underwater topographic data to improve the quality of the new underwater topographic digital elevation model. In the prior art, there are many methods for interpolating underwater topographic data, such as extracting the boundary lines and deep-sea lines on both sides of the river, encrypting the middle line between the boundary lines and deep-sea lines on both sides of the river, intersecting with the measured cross-sectional lines of the river, and generating river elevation points by directional interpolation; adding logical sections between fixed sections using the spline interpolation method, adding longitudinal lines along the river direction to form a grid, and using the Kriging interpolation algorithm to interpolate the elevation of the grid points in the fixed section; by incorporating the characteristic topographic boundaries into the river grid division process, interpolating the elevation of the interpolated cross-sectional nodes based on the distance weighted method; by interpolating the supplementary sections in the order from upstream to downstream and from left bank to right bank, based on the riverbed elevation of the cross-nodes between adjacent measured sections, encoding and matching the node coordinates with the riverbed elevation, and realizing the refined interpolation calculation of the river terrain. These methods have complex data processing steps, low automation, and low computational efficiency and accuracy.

[0005] Therefore, based on some of the problems that still exist in the above prior art, the present application conducts further research in this direction. Summary of the invention

[0006] In view of the above shortcomings in the prior art, the present invention provides a method for reconstructing underwater topography of a river channel based on cross-sectional data, which only encrypts the sampling points of the dredged river section, simplifies the data processing steps, improves the calculation efficiency, and enhances the quality of the digital elevation of the underwater topography of the river channel.

[0007] In order to solve the above technical problems, the present invention is solved by the following technical solutions.

[0008] A method for reconstructing underwater terrain of a river channel based on cross-section data, comprising the following steps: S10: drawing the boundary of the dredging area: drawing the dredging range of the river channel according to the actual dredging work range; S20: extracting the upstream and downstream river sections of the dredging area: extracting the upstream and downstream dividing lines of the dredging area , ,according to , The distance between them is extended upstream and downstream along the center line of the river. When the distance is less than the requirement, it is cut off at the starting point or end point of the river section to obtain the boundary line of the upstream and downstream river sections. , ,according to , Get the upstream and downstream river sections of the dredging area. S30: Extraction of digital elevation model terrain data: Convert the original digital elevation model terrain data format, extract the elevation point data in the original digital elevation model according to the upstream and downstream river sections of the dredging area, and remove the elevation point data in the dredging area; S40: Arrangement of sampling points: Arrangement of horizontal and vertical interpolation sections, upstream and downstream dividing lines of the dredging area , Boundary sampling points are arranged at the intersection of the measured section and the longitudinal interpolation section, section sampling points are arranged at the intersection of the measured section and the longitudinal interpolation section, and ordinary sampling points are arranged at the intersection of the horizontal and vertical interpolation sections in the dredging area; S50: Sampling point elevation calculation: The elevation values ​​of the boundary sampling points are calculated according to the original digital elevation model, the elevation values ​​of the section sampling points are calculated using the Spline interpolation fitting method, and the elevation values ​​of the ordinary sampling points are calculated according to the elevations of the boundary sampling points and the section sampling points; S60: Digital elevation model reconstruction: The extracted terrain data, the newly measured section data, and the encrypted sampling point data are merged to generate a digital elevation model, and merged with the original digital elevation model.

[0009] Further, step S20 includes the following steps: S21: Extraction of river centerline: Extract the river centerline according to the river range. S22: Extraction of upstream and downstream boundary lines of dredging range: Find the points A and B at the upper and lower reaches of the dredging area, and obtain the upstream and downstream boundary lines of the dredging area through points A and B and perpendicular to the river centerline. , S23: Extraction of upstream and downstream river boundary of desilting area: Calculated , The distance between ,by , As the starting line, extend upstream and downstream along the center line of the river. Distance, lack of distance Then the boundary line of the upstream and downstream river sections is obtained by cutting off at the starting point or end point of the river section. , ,according to , Get the upstream and downstream river sections of the dredging area. , The following conditions must be met, namely: .

[0010] Further, step S30 includes the following steps: S31: Digital elevation model terrain data conversion: converting the original digital elevation model from raster format to vector format to obtain elevation point data. S32: Extracting elevation point data of the surrounding area of ​​dredging: extracting elevation point data according to the upstream and downstream river sections of the dredging area, and removing the elevation point data in the dredging area.

[0011] Furthermore, step S40 includes the following steps: S41: Layout of transverse and longitudinal sections: along the river flow direction, set the spacing of interpolated transverse sections according to the upstream and downstream boundary of the dredging area. , Distance, layout of transverse interpolation section; along the section direction, set the interpolation longitudinal section spacing, layout of longitudinal interpolation section. S42: Sampling point layout: upstream and downstream dividing line of dredging area , Boundary sampling points are arranged at the intersection with the longitudinal interpolation section; section sampling points are arranged at the intersection of the measurement section and the longitudinal interpolation section; in the dredging area, ordinary sampling points are arranged at the intersection of the horizontal and longitudinal interpolation sections.

[0012] Further, step S50 includes the following steps: S51: Calculation of elevation values ​​of boundary sampling points: Extracting corresponding elevation values ​​from the original digital elevation model according to the horizontal and vertical coordinates of the boundary sampling points. S52: Calculation of elevation values ​​of section sampling points: Performing Spline interpolation fitting on the measurement data of several sections within the desilting range. For each section, organize the measurement data into ( , ) form, where To measure the distance from the data to the left bank of the river, is the elevation value of the measured data, is the measurement data serial number, and the distance from the cross-section sampling point to the left bank boundary of the river is , the corresponding elevation value is . is an interpolation node, in the interval middle, ;in, is the coefficient to be determined.

[0013] in,( , )satisfy:

[0014] .

[0015] S53: Calculation of common sampling point elevation: Calculate the common sampling point elevation between adjacent measured sections or upstream and downstream dividing lines. The first cross section of the The elevation value of the common sampling points (from the left bank to the right bank of the river) is , the upstream measured section or the first The elevation value of the sampling points (from the left bank to the right bank of the river) is , the downstream measured section or the first The elevation value of the sampling points (from the left bank to the right bank of the river) is , the distance from the common sampling point to its upstream measured section or dividing line is , the distance between adjacent measured sections or dividing lines is , calculate the elevation of the common sampling point according to the distance relationship between the two, that is:

[0016] .

[0017] Further, step S60 includes the following steps: S61: Digital elevation model: The extracted terrain data, the newly measured cross-section data, and the encrypted sampling point data are merged to generate a digital elevation model of the upstream and downstream river sections of the dredging area. S62: Digital elevation model fusion: The generated digital elevation model (new DEM) is merged with the original digital elevation model (original DEM), and the pixel elevation value of the generated digital elevation model (new DEM) is , the original digital elevation model (original DEM) pixel elevation value is .when When available, the fused digital elevation model (DEM) pixel elevation value for ;when If no value is given, the fused digital elevation model (DEM) pixel elevation value for ,Right now:

[0018] .

[0019] The technical effect of the present invention is as follows: the desilting section and the upstream and downstream areas are selected for data interpolation, which reduces the workload of data calculation. The elevation of the basic sampling points in the desilting area is calculated by boundary sampling points and cross-section sampling points, which simplifies the data processing steps and improves the calculation efficiency. According to the cross-section data measured in the desilting section and the original digital elevation model, a low-cost, high-quality digital elevation model of the underwater terrain of the river section after desilting is obtained, which is convenient for providing a scientific basis for the protection and management of the river section and the construction projects within the management scope of the river section in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the steps of a method for reconstructing underwater terrain of a river channel based on cross-sectional data in this application.

[0021] Figure 2 A schematic diagram of the processing of extracting the upstream and downstream river sections of the dredging area in one implementation.

[0022] Figure 3 A schematic diagram of a process for extracting terrain data from a digital elevation model in one implementation.

[0023] Figure 4 A schematic diagram of sampling points in one implementation.

[0024] Figure 5 A schematic diagram of a process for reconstructing a digital elevation model in one implementation is shown. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] In view of some shortcomings of the current existing technology, the present invention provides a river underwater terrain reconstruction method based on cross-section data, which only encrypts the sampling points of the dredged river section, simplifies the data processing steps, improves the calculation efficiency, and improves the quality of the river underwater terrain digital elevation. Figure 1 , a method for reconstructing underwater terrain of a river channel based on cross-section data in this application includes the following steps.

[0027] Step 1: Drawing of desilting area boundaries: Draw the desilting area of ​​the river according to the actual working scope of the desilting.

[0028] Step 2: Extract the upstream and downstream river sections of the dredging area: Extract the upstream and downstream dividing lines of the dredging area , ,according to , The distance between them is extended upstream and downstream along the center line of the river. When the distance is less than the requirement, it is cut off at the starting point or end point of the river section to obtain the boundary line of the upstream and downstream river sections. , ,according to , Get the upstream and downstream river sections of the dredging area.

[0029] Specifically, the second step includes the following steps.

[0030] S21: River centerline extraction: Extract the river centerline based on the river range.

[0031] S22: Extraction of upstream and downstream boundary lines of the dredging area: Find the points A and B at the upper and lower reaches of the dredging area, and pass through points A and B and perpendicular to the center line of the river to obtain the upstream and downstream boundary lines of the dredging area. , .

[0032] S23: Extraction of upstream and downstream river boundary of dredging area: calculated , The distance between ,by , As the starting line, extend upstream and downstream along the center line of the river. Distance, lack of distance Then the boundary line of the upstream and downstream river sections is obtained by cutting off at the starting point or end point of the river section. , ,according to , Get the upstream and downstream river sections of the dredging area.

[0033] in: , The following conditions must be met, namely: .

[0034] In a specific embodiment, Figure 2 As shown, Figure 2 The left side of the figure is a schematic diagram of the river channel, in which the dark area is the area in the river channel that needs to be dredged. After processing, it is transformed into the schematic diagram on the right. It can be seen from the schematic diagram on the right that the length of the AB section of the dredging area is 123m, that is, , The distance between =123m, =150m, according to Determine the distance , , and then the upstream and downstream river section range CD of the dredging area is obtained, that is, the extraction of the upstream and downstream river section range of the dredging area is completed.

[0035] Step 3: Extraction of digital elevation model terrain data: Convert the original digital elevation model terrain data format, extract the elevation point data in the original digital elevation model according to the upstream and downstream river sections of the dredging area, and remove the elevation point data in the dredging area.

[0036] Specifically, the third step includes the following steps.

[0037] S31: Digital elevation model terrain data conversion: Convert the original digital elevation model from raster format to vector format to obtain elevation point data.

[0038] S32: Extraction of elevation point data in the surrounding area of ​​dredging: Extract elevation point data according to the upstream and downstream river sections of the dredging area, and remove the elevation point data in the dredging area.

[0039] In a specific embodiment, Figure 3 As shown, Figure 3 The leftmost part is the upstream and downstream river sections of the dredging area in the original digital elevation model. After being converted into vector format, it is Figure 3 The middle diagram in the figure is then obtained after removing the elevation point data in the desilting area. Figure 3 The right schematic diagram in .

[0040] Step 4: Set up sampling points: Set up horizontal and vertical interpolation sections, and the upstream and downstream boundaries of the dredging area , Boundary sampling points are arranged at the intersection with the longitudinal interpolation section, section sampling points are arranged at the intersection of the measurement section and the longitudinal interpolation section, and ordinary sampling points are arranged at the intersection of the horizontal and longitudinal interpolation sections within the dredging area.

[0041] Specifically, the fourth step includes the following steps.

[0042] S41: Layout of transverse and longitudinal sections: along the river flow direction, set the spacing of interpolated transverse sections according to the upstream and downstream dividing lines of the dredging area. , Distance, layout of transverse interpolation sections; along the section direction, set the interpolation longitudinal section spacing, layout of longitudinal interpolation sections.

[0043] S42: Sampling point layout: upstream and downstream boundary of dredging area , Boundary sampling points are arranged at the intersection with the longitudinal interpolation section; section sampling points are arranged at the intersection of the measurement section and the longitudinal interpolation section; in the dredging area, ordinary sampling points are arranged at the intersection of the horizontal and longitudinal interpolation sections.

[0044] In a specific embodiment, Figure 4 As shown, you can see the settings of each sampling point.

[0045] Step 5: Calculate the elevation of sampling points: Calculate the elevation of boundary sampling points according to the original digital elevation model, calculate the elevation of cross-section sampling points using the Spline interpolation fitting method, and calculate the elevation of common sampling points according to the elevations of boundary sampling points and cross-section sampling points;

[0046] Specifically, the fifth step includes the following steps.

[0047] S51: Calculation of elevation values ​​of boundary sampling points: extracting corresponding elevation values ​​from the original digital elevation model according to the horizontal and vertical coordinates of the boundary sampling points.

[0048] S52: Calculation of elevation values ​​of cross-section sampling points: Spline interpolation fitting is performed on the measurement data of several cross-sections within the desilting range. For each cross-section, the measurement data is sorted into ( , ) form, where To measure the distance from the data to the left bank of the river, is the elevation value of the measured data, is the measurement data serial number, and the distance from the cross-section sampling point to the left bank boundary of the river is , the corresponding elevation value is . is an interpolation node, in the interval middle:

[0049] ,in, is the coefficient to be determined.

[0050] and,( , )satisfy:

[0051] .

[0052] S53: Calculation of common sampling point elevation: Calculate the common sampling point elevation between adjacent measured sections or upstream and downstream dividing lines. The first cross section of the The elevation value of the common sampling points (from the left bank to the right bank of the river) is , the upstream measured section or the first The elevation value of the sampling points (from the left bank to the right bank of the river) is , the downstream measured section or the first The elevation value of the sampling points (from the left bank to the right bank of the river) is , the distance from the common sampling point to its upstream measured section or dividing line is , the distance between adjacent measured sections or dividing lines is , calculate the elevation of the common sampling point according to the distance relationship between the two, that is:

[0053] .

[0054] Step 6: Reconstruction of digital elevation model: Merge the extracted terrain data, newly measured cross-section data, and encrypted sampling point data to generate a digital elevation model, and merge it with the original digital elevation model.

[0055] Specifically, the sixth step includes the following steps.

[0056] S61: Digital elevation model: The extracted terrain data, newly measured cross-section data, and encrypted sampling point data are combined to generate a digital elevation model of the upstream and downstream river sections of the dredging area.

[0057] S62: Digital elevation model fusion: The generated digital elevation model (new DEM) is fused with the original digital elevation model (original DEM). The pixel elevation value of the generated digital elevation model (new DEM) is , the original digital elevation model (original DEM) pixel elevation value is .when When available, the fused digital elevation model (DEM) pixel elevation value for ;when If no value is given, the fused digital elevation model (DEM) pixel elevation value for ,Right now:

[0058] .

[0059] In a specific embodiment, Figure 5 As shown, the fusion process can be seen.

[0060] It can be seen from the above description that in this application, the desilting section and the upstream and downstream areas are selected for data interpolation, which reduces the workload of data calculation. The basic sampling point elevations within the desilting area are calculated by boundary sampling points and cross-section sampling points to simplify the data processing steps and improve the calculation efficiency. Reconstruction is performed based on the cross-section data measured in the desilting section and the original digital elevation model to obtain a low-cost, high-quality digital elevation model of the underwater terrain of the river section after desilting, which is convenient for providing a scientific basis for the protection and management of the river section and construction projects within the scope of the river section management in the later stage.

[0061] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope of the present invention shall be based on the claims. Any replacement, deformation, and improvement of the technology that can be easily thought of by technicians in this field shall fall within the protection scope of the present invention.

Claims

1. A method for reconstructing underwater terrain of a river channel based on cross-section data, characterized in that: The following steps are involved: S10: Drawing of desilting area boundary: Draw the desilting area of ​​the river channel according to the actual desilting work scope; S20: Extraction of upstream and downstream river sections in the dredging area: Extract the upstream and downstream dividing lines of the dredging area , ,according to , The distance between them is extended upstream and downstream along the center line of the river. When the distance is less than the requirement, it is cut off at the starting point or end point of the river section to obtain the boundary line of the upstream and downstream river sections. , ,according to , Get the upstream and downstream river sections of the dredging area; S30: Extracting terrain data from a digital elevation model: converting the original terrain data format of the digital elevation model, extracting elevation point data from the original digital elevation model according to the upstream and downstream river sections of the dredging area, and removing the elevation point data in the dredging area; S40: Set up sampling points: set up transverse and longitudinal interpolation sections, and the upstream and downstream boundary lines of the dredging area , Boundary sampling points are arranged at the intersections with the longitudinal interpolation sections, section sampling points are arranged at the intersections of the measurement section and the longitudinal interpolation sections, and ordinary sampling points are arranged at the intersections of the horizontal and longitudinal interpolation sections within the desilting area; S50: Sampling point elevation calculation: Calculate the boundary sampling point elevation value according to the original digital elevation model, calculate the cross-section sampling point elevation value using the Spline interpolation fitting method, and calculate the common sampling point elevation value according to the boundary sampling point and cross-section sampling point elevation; S60: Digital elevation model reconstruction: The extracted terrain data, newly measured cross-section data, and encrypted sampling point data are combined to generate a digital elevation model, which is then integrated with the original digital elevation model.

2. A method for reconstructing underwater terrain of a river channel based on cross-sectional data according to claim 1, characterized in that: Step S20 also includes the following steps: S21: River centerline extraction: Extract the river centerline according to the river range; S22: Extraction of upstream and downstream boundary lines of the dredging area: Find the points A and B at the upper and lower reaches of the dredging area, and pass through points A and B and perpendicular to the center line of the river to obtain the upstream and downstream boundary lines of the dredging area. , ; S23: Extraction of upstream and downstream river boundary of dredging area: calculated , The distance between ,by , As the starting line, extend upstream and downstream along the center line of the river. Distance, lack of distance Then the boundary line of the upstream and downstream river sections is obtained by cutting off at the starting point or end point of the river section. , ,according to , Get the upstream and downstream river sections of the dredging area; in , The following conditions must be met: .

3. A method for reconstructing underwater terrain of a river channel based on cross-sectional data according to claim 2, characterized in that: Step S30 also includes the following steps: S31: Digital elevation model terrain data conversion: convert the original digital elevation model from raster format to vector format to obtain elevation point data; S32: Extraction of elevation point data in the surrounding area of ​​dredging: Extract elevation point data according to the upstream and downstream river sections of the dredging area, and remove the elevation point data in the dredging area.

4. A method for reconstructing underwater terrain of a river channel based on cross-sectional data according to claim 3, characterized in that: Step S40 also includes the following steps: S41: Layout of transverse and longitudinal sections: along the river flow direction, set the spacing of interpolated transverse sections according to the upstream and downstream dividing lines of the dredging area. , Distance, layout of transverse interpolation sections; along the section direction, set the interpolation longitudinal section spacing, layout of longitudinal interpolation sections; S42: Sampling point layout: upstream and downstream boundary of dredging area , Boundary sampling points are arranged at the intersection with the longitudinal interpolation section; section sampling points are arranged at the intersection of the measurement section and the longitudinal interpolation section; in the dredging area, ordinary sampling points are arranged at the intersection of the horizontal and longitudinal interpolation sections.

5. A method for reconstructing underwater terrain of a river channel based on cross-sectional data according to claim 4, characterized in that: Step S50 also includes the following steps: S51: Calculation of elevation values ​​of boundary sampling points: extracting corresponding elevation values ​​from the original digital elevation model according to the horizontal and vertical coordinates of the boundary sampling points; S52: Calculation of elevation values ​​of cross-section sampling points: Spline interpolation fitting is performed on the measurement data of several cross-sections within the desilting range; for each cross-section, the measurement data is sorted into ( , ) form, where To measure the distance from the data to the left bank of the river, is the elevation value of the measured data, is the measurement data serial number, and the distance from the cross-section sampling point to the left bank boundary of the river is , the corresponding elevation value is , is the interpolation node, in the interval middle: ， in, is the coefficient to be determined; ( , )satisfy: ; S53: Calculation of common sampling point elevation: Calculate the common sampling point elevation between adjacent measured sections or upstream and downstream dividing lines. The first cross section of the The elevation value of the common sampling point from the left bank to the right bank of the river is , the upstream measured section or the first The elevation value of the sampling point from the left bank to the right bank of the river is , the downstream measured section or the first The elevation value of the sampling point from the left bank to the right bank of the river is , the distance from the common sampling point to its upstream measured section or dividing line is , the distance between adjacent measured sections or dividing lines is , calculate the elevation of the common sampling point according to the distance relationship between the two, that is: 。 6. A method for reconstructing underwater terrain of a river channel based on cross-sectional data according to claim 5, characterized in that: Step S60 also includes the following steps: S61: Digital elevation model: The extracted terrain data, newly measured cross-section data, and encrypted sampling point data are combined to generate a digital elevation model of the upstream and downstream river sections of the dredging area; S62: Digital elevation model fusion: The generated digital elevation model-new DEM is fused with the original digital elevation model-original DEM. The pixel elevation value of the generated digital elevation model-new DEM is , the original digital elevation model-the original DEM pixel elevation value is ; when When available, the fused digital elevation model-DEM pixel elevation value for ; when When there is no value, the fused digital elevation model-DEM pixel elevation value for ,Right now: 。

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