Channel topographic change comparative analysis method and device

Abstract

The invention provides a channel topographic change comparative analysis method and device, and the method comprises the steps: obtaining maps of different measurement times, and extracting topographic point coordinates, topographic point elevations and closed boundary lines; carrying out grid division on an area in the closed boundary line to generate a two-dimensional unstructured grid; interpolation is carried out on the topographic point coordinates and the topographic point elevations corresponding to all the measurement times on the two-dimensional unstructured grid, and the elevations corresponding to all the measurement times at grid nodes are obtained; calculating the elevation difference of the grid nodes corresponding to the two measurement times needing to be compared; and drawing a topographic change distribution diagram. According to the method, quantitative analysis of the elevation change of the terrain point is realized, meanwhile, the method can also improve the problem of large analysis result error caused by excessive interpolation times and non-uniform grid nodes and sizes during analysis of an existing method, the precision of the terrain change analysis result is improved, and the accuracy of the terrain change analysis result can be improved by drawing an elevation change distribution diagram. And the topographic change distribution of the channel topographic survey area is visually reflected.

Description

Technical Field

[0001] The present invention relates to the technical field of waterway engineering terrain analysis, and in particular to a method and device for comparing and analyzing waterway terrain changes. Background Art

[0002] At present, the channel topography survey mainly adopts the method of carrying a sounder on a ship and traveling along the sounding line. The sounder is set to transmit signals at a certain frequency to obtain data, record the coordinate values ​​of the topographic points on the sounding line and the water depth value, and then convert the water depth value into the elevation value through the base surface conversion relationship. After the ship completes the journey along the sounding line, all the measured topographic points constitute the topographic map of the survey area. However, for different channel topography surveys, even if the sounding line layout is the same, the ship can only roughly travel along the sounding line when traveling, and it is impossible to ensure that the route and the measured topographic coordinate points of each survey are exactly the same. Therefore, it is usually difficult to achieve the overlap of the topographic elevation points obtained between different surveys, and thus it is impossible to analyze the changes in channel topography point by point.

[0003] At present, the analysis of waterway terrain change mainly adopts the method of forming a terrain elevation surface through grid interpolation for each measured terrain elevation point. The terrain elevation surfaces of the previous and next measurements are used as the reference surface and the comparison surface respectively, and a calculated surface is regenerated as the analysis object of waterway terrain change, mainly to analyze the erosion and siltation of waterway terrain. In the existing analysis method, the terrain elevation points of the previous and next measurements need to be interpolated once to form a surface, and the calculated surface also needs to be interpolated once. There are three different interpolations in the analysis process. Too many interpolations and inconsistent interpolation grids will cause large errors in the analysis results of terrain change, and the analysis of erosion and siltation is too macroscopic. The existing method can neither quantitatively analyze the changes in waterway terrain from the perspective of each microscopic terrain point, nor can it accurately and intuitively reflect the overall distribution of terrain changes from the overall perspective. Summary of the invention

[0004] The purpose of the present invention is to address the defects of the prior art and to provide a method and device for comparing and analyzing waterway terrain changes. This method can improve the existing method, which only focuses on terrain scouring and silting analysis while ignoring the analysis of terrain point-by-point change rules when comparing and analyzing terrain changes at different times, and achieve quantitative analysis of terrain point elevation changes. At the same time, this method can also improve the existing method's analysis problems such as too many interpolation times and inconsistent grid nodes and sizes, which lead to large errors in analysis results, improve the accuracy of terrain change analysis results, and can intuitively reflect the distribution of terrain changes in the waterway terrain survey area by drawing an elevation change distribution map. The present invention forms a complete waterway terrain comparison and analysis method from the microscopic and macroscopic, qualitative and quantitative perspectives.

[0005] In order to solve the above technical problems, in a first aspect, the present invention provides a comparative analysis method for waterway terrain changes, comprising:

[0006] Obtain survey maps from different times, extract topographic point coordinates, topographic point elevations, and closed boundary lines;

[0007] Meshing the area within the closed boundary line to generate a two-dimensional unstructured grid;

[0008] The coordinates and elevations of the terrain points corresponding to each measurement are interpolated on a two-dimensional unstructured grid to obtain the elevations corresponding to each measurement at the grid nodes;

[0009] Calculate the elevation difference between the two grid nodes corresponding to the two measurements that need to be compared;

[0010] Draw a distribution map of terrain changes.

[0011] Furthermore, the method of extracting the coordinates of terrain points, the elevation of terrain points and the closed boundary line includes:

[0012] Select any survey and mapping, draw a closed boundary line along the outermost terrain point using a polyline, and save the drawn closed boundary line as a .dxf file;

[0013] Extract the coordinates and elevation data of terrain points in each survey map;

[0014] Convert the coordinates and elevation data of the terrain points of each measurement into .xyz format files, where x and y represent the horizontal and vertical coordinates of the plane respectively, and z represents the elevation value.

[0015] Furthermore, the area within the closed boundary line is meshed to generate a two-dimensional unstructured grid, including:

[0016] Input the closed boundary line file in .dxf format into the SMS software. The area enclosed by the closed boundary line is the meshing area.

[0017] The grid size node spacing is determined based on the set spacing between two adjacent topographic measuring points on the sounding line laid perpendicular to the waterway before the survey;

[0018] According to the meshing area and mesh size node spacing, a two-dimensional unstructured grid is generated in SMS software.

[0019] Furthermore, the coordinates and elevations of the terrain points corresponding to each measurement are interpolated on a two-dimensional unstructured grid to obtain the elevations corresponding to each measurement at the grid nodes, including:

[0020] Input the .xyz format files of each measurement into the two-dimensional unstructured grid file;

[0021] In the SMS software, spatial linear interpolation is performed on each measurement in a two-dimensional unstructured grid, and the terrain points of each measurement are uniformly interpolated on the same set of grid nodes to obtain the elevation of each measurement at the grid node;

[0022] After each interpolation is completed, the SMS files containing both the elevation of the terrain points at the grid nodes and the grid information will be saved in sequence.

[0023] Furthermore, the calculation of the elevation difference at the grid nodes corresponding to the two measurements to be compared includes:

[0024] Determine the two measurements that need to be compared, and extract all the grid node coordinates (x1, y1), (x2, y2)...(x n ,y n ) and its corresponding elevation values ​​z1, z2...z n , denoted as (x1,y1,z1), (x2,y2,z2)...(x n ,y n ,z n ), extract the elevation values ​​z1′, z2′, ...z n ′, recorded as (x1,y1,z1′), (x2,y2,z2′)...(x n ,y n ,z n ′);

[0025] Calculate the elevation change values ​​of the two measurements Δz1=z1′-z1, Δz2=z2′-z2...Δz n =z n ′-z n , the grid node coordinates and elevation change value combinations of the two measurements after interpolation alignment are recorded as (x1, y1, Δz1), (x2, y2, Δz2)...(x n ,y n ,Δz n ).

[0026] Furthermore, the method for drawing a terrain change distribution map includes generating a .mesh format file, and the method for generating the .mesh format file is:

[0027] According to the grid node coordinates and elevation change value combinations (x1, y1, Δz1), (x2, y2, Δz2)...(x n ,y n ,Δz n ), in each combination x i (i=1,2...n) add serial number i, Δz iAfter (i=1,2...n), the boundary information of the grid nodes is added, and the boundaries are all set to closed boundaries. The boundary information values ​​of the grid nodes are uniformly set to 0, and the combinations A(1,x1,y1,Δz1,0), (2,x2,y2,Δz2,0)...(n,x n ,y n ,Δz n ,0),Combination A contains the sequence information, grid node coordinate information, elevation change value information and grid node boundary information;

[0028] According to the sequence information of each grid node in the two-dimensional unstructured grid, the combination B(1,a1,b1,c1),(2,a2,b2,c2)...(j,a j ,b j ,c j ), combination B includes the order of appearance of each grid and the grid node number information that constitutes the two-dimensional unstructured grid. The order of appearance of the grid is automatically generated and determined by the SMS software. The two-dimensional unstructured grid uses an unstructured triangular grid. i 、b i 、c i They represent the node numbers of the three vertices that constitute an unstructured triangular mesh respectively;

[0029] Write combination A, combination B, the number of nodes n, the number of meshes j, and the mesh size node spacing l into a .mesh format file.

[0030] Furthermore, the .mesh format file is

[0031] Furthermore, the method for drawing a terrain change distribution map includes: opening a .mesh format file using MIKE Zero software, selecting to output it as a picture, and saving it as a metafile, so as to obtain a terrain elevation change distribution map between different measurements.

[0032] In a second aspect, the present invention provides a non-transitory computer-readable storage medium for storing a computer program or instruction. When the computer program or instruction is executed by a computer, the method for comparing and analyzing the changes in waterway terrain is implemented.

[0033] In a third aspect, the present invention provides a computer program product, which includes computer instructions; when part or all of the computer instructions are run on a computer, the method for comparing and analyzing changes in waterway terrain is executed.

[0034] The beneficial effects of the present invention are:

[0035] 1. The present invention can solve the problem of the existing method lacking the comparative analysis based on each terrain point as the analysis unit when conducting comparative analysis of terrain changes by aligning terrain elevation points of different measured channels to the same grid nodes, thereby realizing the quantitative analysis of point-to-point changes in terrain elevation.

[0036] 2. During the analysis process, the present invention uses the same set of grids to interpolate terrain points measured at different times, effectively reducing the analysis error caused by grid differences. At the same time, the number of spatial interpolation of coordinate points is reduced from 3 times in the existing method to 2 times in the method of the present invention, which can improve the accuracy of terrain change analysis results.

[0037] 3. The present invention draws an elevation change distribution map by compiling a grid file of coordinate points and elevation change values. The principle is clear, the method steps are concise, the drawing efficiency is high, and the terrain change distribution of the waterway topography survey area can be intuitively reflected. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the process of the present invention;

[0039] Figure 2 It is a closed boundary line of the terrain change analysis area of ​​the present invention;

[0040] Figure 3 Extract the edited .xyz format file for the present invention;

[0041] Figure 4 is a schematic diagram of a two-dimensional unstructured grid of the present invention;

[0042] Figure 5 The distribution of terrain points after interpolation and alignment of a certain measurement in the present invention;

[0043] Figure 6 This is a distribution map of terrain elevation changes between two measurements of the present invention. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] Example 1

[0046] like Figure 1 As shown, this embodiment provides a comparative analysis method for waterway terrain changes, including:

[0047] S1. Obtain maps from different surveys, extract topographic point coordinates, topographic point elevations, and closed boundary lines; specifically include:

[0048] Collect basic terrain AutoCAD mapping. The mapping of different surveys should contain the coordinates and elevation data of terrain points. At the same time, the terrain mapping area between surveys should be the same. Select any survey mapping, use polylines to draw a closed boundary line along the outermost terrain point in AutoCAD, and save the drawn closed boundary line as a .dxf format file;

[0049] The dataextraction command in AutoCAD is used to extract the coordinates and elevation data of terrain points in each survey map;

[0050] Use the notepad in Office software to convert the coordinates and elevation data of each measured terrain point into .xyz format files, such as Figure 3 As shown, x and y represent the horizontal and vertical coordinates of the plane respectively, and z represents the elevation value.

[0051] S2. Mesh the area within the closed boundary line to generate a two-dimensional unstructured grid; specifically, the steps include:

[0052] Input the closed boundary line file in .dxf format into the SMS software. The area enclosed by the closed boundary line is the meshing area. Figure 2 As shown;

[0053] The grid size node spacing l is determined according to the set spacing between two adjacent topographic measuring points on the sounding line laid perpendicular to the waterway before the survey;

[0054] According to the meshing area and the mesh size node spacing l, a two-dimensional unstructured grid is generated in the SMS software, such as Figure 4 shown.

[0055] S3, interpolating the coordinates and elevations of the terrain points corresponding to each measurement on a two-dimensional unstructured grid to obtain the elevations corresponding to each measurement at the grid nodes; specifically including:

[0056] Input the .xyz format files of each measurement into the two-dimensional unstructured grid file;

[0057] In the SMS software, spatial linear interpolation is performed on each measurement in a two-dimensional unstructured grid, and the terrain points of each measurement are uniformly interpolated on the same set of grid nodes to obtain the elevation of each measurement at the grid node, such as Figure 5 As shown;

[0058] After each interpolation is completed, the SMS files containing both the elevation of the terrain points at the grid nodes and the grid information are saved in sequence to form a .geo format file.

[0059] S4. Calculate the elevation difference at the grid nodes corresponding to the two measurements to be compared; specifically including:

[0060] Determine the two measurements that need to be compared, and extract all grid node coordinates (x1, y1), (x2, y2)...(x n ,y n ) and the corresponding elevation values ​​z1, z2...z at the grid nodes of the previous measurement n , denoted as (x1,y1,z1), (x2,y2,z2)...(x n ,y n ,z n ), extract the elevation values ​​z1′, z2′, ... z1′ corresponding to the next measurement at the grid node n ′, recorded as (x1,y1,z1′), (x2,y2,z2′)...(x n ,y n ,z n ′); n means there are n network nodes;

[0061] Calculate the elevation change values ​​of the two measurements Δz1=z1′-z1, Δz2=z2′-z2...Δz n =z n ′-z n , the grid node coordinates and elevation change value combinations of the two measurements after interpolation alignment are recorded as (x1, y1, Δz1), (x2, y2, Δz2)...(x n ,y n ,Δz n ).

[0062] S5. Draw a distribution map of terrain changes; specifically including:

[0063] According to the grid node coordinates and elevation change value combinations (x1, y1, Δz1), (x2, y2, Δz2)...(x n ,y n ,Δz n ), in each combination x i (i=1,2...n) add serial number i, Δz i After (i=1,2...n), the boundary information of the grid nodes is added, and the boundaries are all set to closed boundaries. The boundary information values ​​of the grid nodes are uniformly set to 0, and the combinations A(1,x1,y1,Δz1,0), (2,x2,y2,Δz2,0)...(n,x n ,y n ,Δz n ,0),Combination A contains the sequence information, grid node coordinate information, elevation change value information and grid node boundary information;

[0064] According to the sequence information of each grid node in the two-dimensional unstructured grid, the combination B(1,a1,b1,c1),(2,a2,b2,c2)...(j,a j ,b j ,c j ), combination B includes the order of appearance of each grid and the grid node number information that constitutes the two-dimensional unstructured grid. The order of appearance of the grid is automatically generated and determined by the SMS software. The two-dimensional unstructured grid uses an unstructured triangular grid. i 、b i 、c i They represent the node numbers of the three vertices that constitute an unstructured triangular mesh respectively;

[0065] The combination A, the combination B, the number of nodes n, the number of grids j and the grid size node spacing l are written into a .mesh format file. The .mesh format file is a file format that can be recognized by the MIKEZero software.

[0066] The .mesh format file is

[0067] Open the .mesh file using MIKE Zero software, select export as image, save as metafile, and you can get the terrain elevation change distribution map between different measurements, such as Figure 6 shown.

[0068] Example 2

[0069] This embodiment provides a non-transitory computer-readable storage medium for storing a computer program or instruction. When the computer program or instruction is executed by a computer, the comparison and analysis method of waterway terrain changes in Embodiment 1 is implemented.

[0070] Example 3

[0071] The present invention provides a computer program product, which includes computer instructions. When part or all of the computer instructions are run on a computer, the comparison and analysis method of waterway terrain changes in Example 1 is executed.

[0072] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A comparative analysis method for waterway topography changes, characterized in that: include: Obtain survey maps from different times, extract topographic point coordinates, topographic point elevations, and closed boundary lines; Meshing the area within the closed boundary line to generate a two-dimensional unstructured grid; The coordinates and elevations of the terrain points corresponding to each measurement are interpolated on a two-dimensional unstructured grid to obtain the elevations corresponding to each measurement at the grid nodes; Calculate the elevation difference between the two grid nodes corresponding to the two measurements that need to be compared; Draw a distribution map of terrain changes.

2. The comparative analysis method of waterway topography change according to claim 1 is characterized in that: Methods for extracting topographic point coordinates, topographic point elevations, and closed boundary lines include: Select any survey and mapping, draw a closed boundary line along the outermost terrain point using a polyline, and save the drawn closed boundary line as a .dxf file; Extract the coordinates and elevation data of terrain points in each survey map; Convert the coordinates and elevation data of the terrain points of each measurement into .xyz format files, where x and y represent the horizontal and vertical coordinates of the plane respectively, and z represents the elevation value.

3. The comparative analysis method of waterway topography change according to claim 2 is characterized in that: Mesh the area within the closed boundary line to generate a two-dimensional unstructured grid, including: Input the closed boundary line file in .dxf format into the SMS software. The area enclosed by the closed boundary line is the meshing area. The grid size node spacing is determined based on the set spacing between two adjacent topographic measuring points on the sounding line laid perpendicular to the waterway before the survey; According to the meshing area and mesh size node spacing, a two-dimensional unstructured grid is generated in SMS software.

4. The comparative analysis method of waterway topography change according to claim 3 is characterized in that: The coordinates and elevations of the terrain points corresponding to each measurement are interpolated on a two-dimensional unstructured grid to obtain the elevations corresponding to each measurement at the grid nodes, including: Input the .xyz format files of each measurement into the two-dimensional unstructured grid file; In the SMS software, spatial linear interpolation is performed on each measurement in a two-dimensional unstructured grid, and the terrain points of each measurement are uniformly interpolated on the same set of grid nodes to obtain the elevation of each measurement at the grid node; After each interpolation is completed, the SMS files containing both the elevation of the terrain points at the grid nodes and the grid information will be saved in sequence.

5. The comparative analysis method of waterway topography change according to claim 4 is characterized in that: Calculating the elevation difference at the grid nodes corresponding to the two measurements that need to be compared includes: Determine the two measurements that need to be compared, and extract all grid node coordinates (x1, y1), (x2, y2)...(x n ,y n ) and the corresponding elevation values ​​z1, z2...z at the grid nodes of the previous measurement n , denoted as (x1,y1,z1), (x2,y2,z2)...(x n ,y n ,z n ), extract the elevation values ​​z1′, z2′, ... z1′ corresponding to the next measurement at the grid node n ′, recorded as (x1,y1,z1′), (x2,y2,z2′)…)x n ,y n ,z n ′); Calculate the elevation change values ​​of the two measurements Δz1=z1′-z1, Δz2=z2′-z2...Δz n =z n ′-z n , the grid node coordinates and elevation change value combinations of the two measurements after interpolation alignment are recorded as (x1, y1, Δz1), (x2, y2, Δz2)...(x n ,y n ,Δz n ).

6. The comparative analysis method of waterway topography change according to claim 5 is characterized in that: The method for drawing a terrain change distribution map includes generating a .mesh format file. The method for generating a .mesh format file is: According to the grid node coordinates and elevation change value combinations (x1, y1, Δz1), (x2, y2, Δz2)...(x n ,y n ,Δz n ), in each combination x i (i=1,2...n) add serial number i, Δz i After (i=1,2...n), the boundary information of the grid nodes is added, and the boundaries are all set to closed boundaries. The boundary information values ​​of the grid nodes are uniformly set to 0, and the combinations A(1,x1,y1,Δz1,0), (2,x2,y2,Δz2,0)...(n,x n ,y n ,Δz n ,0),Combination A contains the sequence information, grid node coordinate information, elevation change value information and grid node boundary information; According to the sequence information of each grid node in the two-dimensional unstructured grid, the combination B(1,a1,b1,c1),(2,a2,b2,c2)...(j,a j ,b j ,c j ), combination B includes the order of appearance of each grid and the grid node number information that constitutes the two-dimensional unstructured grid. The order of appearance of the grid is automatically generated and determined by the SMS software. The two-dimensional unstructured grid uses an unstructured triangular grid. i 、b i 、c i They represent the node numbers of the three vertices that constitute an unstructured triangular mesh respectively; Write combination A, combination B, the number of nodes n, the number of meshes j, and the mesh size node spacing l into a .mesh format file.

7. The comparative analysis method of waterway topography change according to claim 6 is characterized in that: The .mesh format file is 8. The comparative analysis method of waterway topography change according to claim 6, characterized in that: The method of drawing a terrain change distribution map includes: opening the .mesh format file using MIKE Zero software, selecting to output as a picture, and saving as a metafile, so as to obtain a terrain elevation change distribution map between different measurements.

9. A non-transitory computer-readable storage medium, characterized in that: Used to store computer programs or instructions, when the computer programs or instructions are executed by a computer, the comparison and analysis method of waterway terrain changes as described in any one of claims 1-8 is implemented.

10. A computer program product, characterized in that The computer program product includes computer instructions; when part or all of the computer instructions are run on a computer, the comparative analysis method of waterway terrain changes according to any one of claims 1 to 8 is executed.

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