Method for generating reservoir area river channel cross section by fusing multi-source data and encrypting step by step

Abstract

The invention discloses a method for generating a reservoir area river channel cross section by fusing multi-source data and encrypting step by step, and relates to the field of hydropower engineering measurement. The method comprises the steps of obtaining multi-source data of a reservoir area river channel section, and performing fusion processing on the multi-source data to obtain a point cloud set Q; laying section line segments, and determining an initial section data set A according to the laid section line segments; obtaining topographic feature points on the section line segments to form a new section data set B; obtaining a new section data set C; forming a new section data set D; converting the section data set D into a section mileage file; and drawing the mileage file into a cross section diagram, and further generating a reservoir area river channel cross section. According to the method, multi-source data are fused into point cloud data of the whole reservoir bank area, data sources comprise true color airborne laser point cloud data of the shore part, elevation point data collected by an underwater unmanned ship and elevation point data manually collected by a reservoir close to the shore and a shallow water area, and high precision and comprehensiveness of the data sources are guaranteed.

Description

Technical Field

[0001] The invention relates to the field of hydropower engineering surveying, and in particular to a method for fusing multi-source data and gradually encrypting to generate a river cross section in a reservoir area. Background Art

[0002] In the field of river or reservoir cross-section measurement in hydropower engineering special surveys, the current cross-section measurement methods mainly include traditional manual measurement methods and point cloud extraction methods. The traditional manual measurement method has the advantages of high accuracy but low efficiency. The point cloud extraction method extracts cross-sections mainly by generating DEM or irregular triangulated elevation points to extract cross-section data. The advantage is high efficiency but low data accuracy in the water area. Therefore, it is necessary to provide a river cross-section generation method that can improve data accuracy. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a method for fusing multi-source data and generating a river cross section of a reservoir area through step-by-step encryption.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A method for fusing multi-source data and encrypting step by step to generate a cross section of a river channel in a reservoir area comprises the following steps: step S1, obtaining multi-source data of a river channel section in a reservoir area, and fusing the multi-source data to obtain a point cloud set Q; step S2, laying out section line segments, and determining an initial section data set A according to the laid out section line segments, wherein the data set A includes the start and end point data of the section; step S3, obtaining terrain feature points on the section line segments, and adding them to the section data set A to form a new section data set B; step S4, obtaining the contour endpoints of objects on the section line segments according to the colored point cloud set Q, adding them to the section data set B, and adding object attribute labels to the section points to obtain a new section data set C; step S5, encrypting the section points according to the section spacing requirements of different scales required by the hydropower engineering measurement specification to form a new section data set D; step S6, converting the section data set D into a mileage file of the section, that is, each point D on the line segment i (X, Y, Z) is converted into (mileage value, elevation value, attribute value); Step S7, the mileage file is drawn as a cross-section diagram, and then the river cross-section of the reservoir area is generated.

[0006] Based on the above technical solution, further, in step S1, the multi-source data includes point cloud data collected by airborne lidar, river underwater elevation point data collected by unmanned boats, and artificial elevation point data collected by RTK.

[0007] Based on the above technical solution, further, in step S1, the fusion processing process is: coloring, denoising, classifying, and coordinate conversion are performed on the point cloud data collected by the airborne lidar to obtain a ground point cloud set R with RGB color in the engineering coordinate system; the underwater elevation point data of the river collected by the unmanned boat and the artificial elevation point data collected by RTK in the acquired multi-source data are converted into the engineering coordinate system and converted into a point cloud file in las format, and merged into the point cloud set R to form a new point cloud set Q.

[0008] Based on the above technical solution, further, the specific method of converting to las format is: first organize the river underwater elevation point data and artificial elevation point data into a fixed format of Excel table, in which the first column is the point number, the second column is the X coordinate under the engineering coordinate system, the third column is the Y coordinate under the engineering coordinate system, and the fourth column is the Z coordinate of the elevation value; after sorting, save the file as csv format, and then use the LasWrite function in MATLAB to write the las file.

[0009] Based on the above technical solution, further, in step S3, the process of obtaining terrain feature points includes the following steps: step S31, calculating the plane coordinates of the interpolation point Mn of the cross-section line segment: interpolate a point every λ from the starting point to the end point of the cross-section line segment, and the coordinates of the interpolation point are (Xn, Yn); step S32, using the KD tree search method to search for the four points nearest to the interpolation point Mn in the point cloud set Q, and calculate the elevation value Zn of the target point according to the inverse distance weighted interpolation method; step S33, determining the terrain feature points on the cross-section line segment according to the change in terrain slope.

[0010] Based on the above technical solution, further, in step S31, the method for calculating the plane coordinates of the interpolation point is:

[0011]

[0012] X n =X 1 +nλ(X 2 -X 1 ) / L;

[0013] Y n =Y 1 +nλ(Y 2 -Y 1 ) / L;

[0014] Where L is the length of the cross-section line segment, (X 1 , Y 1 ) is the starting point coordinate of the cross-section segment, (X 2 , Y 2 ) are the end point coordinates of the section segment.

[0015] Based on the above technical solution, further, in step S32, the calculation process of the elevation value Zn includes the following steps: step S321, using the KD tree search method to search the four coordinates of the closest point to the Mn point in the point cloud set Q, which are Q1 (x1, y1, z1), Q2 (x2, y2, z2), Q3 (x3, y3, z3), and Q4 (x4, y4, z4); step S322, calculating the Euclidean distance from the Mn point to the four points:

[0016] Step S323, set the weight index p and calculate the weight; where p=2; the weight of Q1 is: The weight of Q2 is: The weight of Q3 is: The weights of Q4 are:

[0017] Step S324, calculate the elevation value Zn of the target point:

[0018] Z n =(W 1 Z 1 +W 2 Z 2 +W 3 Z 3 +W 4 Z 4 ) / (W 1 +W 2 +W 3 +W 4 ).

[0019] Based on the above technical solution, further, in step S33, the determination process is: obtain two adjacent points M i 、M i+1 , and calculate the adjacent points M i , M i+1 Slope θ i , the slope θ i Compared with the set slope threshold θ, if the slopes of two adjacent points θ i If the slope is greater than the slope threshold θ, the two points are recorded as terrain feature points, and the terrain feature points, the starting point and the end point together constitute a new cross-section data set B; In the formula, (X i ,Y i ,Z i ) is M i The coordinates of (X i+1 , Y i+1 , Z i+1 ) is M i+1 The coordinates of .

[0020] Based on the above technical solution, further, in step S6, the mileage value calculation process is as follows: along the direction looking toward the downstream of the river, the mileage value of the left endpoint of the line segment is set to 0, and the attribute value left endpoint is marked; the mileage is accumulated toward the right endpoint, the mileage value of the end point of the cross-section line segment is the length of the line segment, the attribute value right endpoint is marked, and the mileage value S of any point in the middle is i :

[0021]

[0022] Based on the above technical solution, further, in step S7, the drawing process is: take the left endpoint of the section segment as the origin, the direction of the section segment as the X-axis, the elevation value as the Z-axis, and mark the mileage value, elevation value, attribute value, and section name information.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The multi-source data in the present invention are fused into the point cloud data of the entire reservoir bank area. The data sources include the true color airborne laser point cloud data of the shore part, the elevation point data collected by the underwater unmanned boat, and the elevation point data collected manually near the shore and the shallow water area of ​​the reservoir, which ensures the high precision and comprehensiveness of the data source. After being uniformly converted into the engineering coordinate system, it is fused into the point cloud las data format to extract the cross-section points, which seamlessly connects with the engineering needs. In addition, four sets AD are set to generate a cross-section point set with high precision, comprehensive terrain features, and no data redundancy by using the step-by-step encryption method. Among them, set A collects the starting point and end point data, set B collects the starting point, terrain feature points, and end point data, set C collects the starting point, terrain feature points, ground feature contour points, and end point data, and set D collects the starting point, terrain feature points, ground feature contour points, minimum spacing point encryption, and end point data. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described and illustrated below in conjunction with the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0027] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0028] Example 1

[0029] Combination Figure 1 As shown, this embodiment provides a method for fusing multi-source data and encrypting step by step to generate a river cross-section in a reservoir area. It proposes to measure part of the water area data by unmanned boats, and to add manual measurement data for the shore and nearby areas that cannot be measured by unmanned boats. The unmanned boat data and the manual measurement data are converted into point cloud format, and fused with the airborne laser point cloud data. A cross-section data set is formed through step-by-step encryption, which can integrate the advantages of multi-source data and has the advantages of high precision and comprehensive data.

[0030] The specific steps include:

[0031] Step S1, obtaining multi-source data related to the river section of the reservoir area, and fusing the multi-source data to obtain a point cloud set Q. The obtained related data include point cloud data collected by airborne laser radar, river underwater elevation point data collected by unmanned boats, and artificial elevation point data collected by RTK.

[0032] In this embodiment, the processing process includes the following steps:

[0033] The point cloud data collected by the airborne laser radar is processed by colorization, denoising, classification, and coordinate conversion through point cloud related professional processing software to obtain a point cloud set R of the ground with RGB color in the engineering coordinate system.

[0034] The underwater elevation point data of the river collected by the unmanned boat and the artificial elevation point data collected by RTK in the acquired multi-source data are converted into the engineering coordinate system and the point cloud file in las format, and merged into the point cloud set R to form a new point cloud set Q. Among them, combined with the actual data situation, the artificially collected engineering points are mainly near-shore data, which cannot be collected by the unmanned boat. That is, the point cloud set R is the airborne laser point cloud data set, and the point cloud set Q is the point cloud data set after the unmanned boat and the artificial measured points are integrated.

[0035] Specifically, the specific method of converting data into las format is: first organize the river underwater elevation point data and artificial elevation point data into a fixed format of Excel table, where the first column is the point number, the second column is the X coordinate in the engineering coordinate system, the third column is the Y coordinate in the engineering coordinate system, and the fourth column is the elevation value Z. After the arrangement is completed, save the file as csv format, and then use the LasWrite function in MATLAB to write the las file.

[0036] Step S2: Determine the initial section data set A according to the laid section line segments, where the data set A includes the start and end data of the section; wherein the section start point A1 (X 1 , Y 1 ) and the end point An(X 2 , Y 2 ) is known. It should be noted that the cross-section line segments are determined according to the actual project requirements, and data acquisition is based on the cross-section line segments to determine the flight range and elevation point collection range to ensure that the data source can cover all cross-section line segments. Furthermore, the layout of the cross-section line segments is mainly based on the actual needs of the project and is arranged in accordance with the hydropower engineering measurement specifications.

[0037] Step S3: Obtain terrain feature points on the cross-section line segment and add them to the cross-section dataset A to form a new cross-section dataset B.

[0038] In this embodiment, the process of obtaining terrain feature points includes the following steps:

[0039] Step S31, calculate the plane coordinates of the interpolation point Mn of the cross-section line segment: interpolate a point every distance λ from the starting point to the end point of the cross-section line segment, and the coordinates of the interpolation point are (Xn, Yn), where the value of λ is set according to the grid spacing of the digital elevation model in the hydropower engineering measurement specification. Specifically, the method for calculating the plane coordinates of the interpolation point is:

[0040]

[0041] X n =X 1 +nλ(X 2 -X 1 ) / L;

[0042] Y n =Y 1 +nλ(Y 2 -Y 1 ) / L;

[0043] Where L is the length of the cross-section line segment, (X 1 , Y 1 ) is the starting point coordinate of the cross-section segment, (X 2 , Y 2) is the coordinate of the end point of the cross-section segment; n takes values ​​of 1, 2, 3, etc.

[0044] Step S32: Search the four points closest to the interpolation point Mn in the point cloud set Q using the KD tree search method, and calculate the elevation value Zn of the target point according to the inverse distance weighted interpolation method. The specific calculation method includes the following steps:

[0045] Step S321: Use the KD tree search method to search for the four coordinates of the points closest to point Mn in the point cloud set Q. 1 (x 1 ,y 1 , z 1 ), Q 2 (x 2 ,y 2 , z 2 ), Q 3 (x 3 ,y 3 , z 3 ), Q 4 (x 4 ,y 4 , z 4 );

[0046] Step S322, calculate the Euclidean distance from point Mn to the four points:

[0047]

[0048]

[0049] Step S3, calculate the weight and set a weight index p. The larger the p value, the smaller the influence of the distant points on the interpolation result. The weight value can be adjusted according to the density of the point cloud. Usually p=2. The specific calculation method is:

[0050] The weight of Q1 is:

[0051] The weight of Q2 is:

[0052] The weight of Q3 is:

[0053] The weights of Q4 are:

[0054] Step S324, calculate the elevation value Zn of the target point:

[0055] Z n =(W 1 Z 1 +W 2 Z 2 +W 3 Z3 +W 4 Z 4 ) / (W 1 +W 2 +W 3 +W 4 ).

[0056] Step S33: determine the terrain feature points on the cross-section line segment according to the change in terrain slope.

[0057] The specific determination method includes: obtaining two adjacent points M i 、M i+1 , and calculate any two adjacent points M on the cross-section segment i 、M i+1 The slope between i , the slope θ i Compared with the set slope threshold θ, if the slopes of two adjacent points θ i If the slope is greater than the slope threshold θ, the two points are recorded as terrain feature points, and the terrain feature points, the starting point and the end point together constitute a new section data set B.

[0058] in, In the formula, (X i ,Y i ,Z i ) is M i The coordinates of (X i+1 , Y i+1 , Z i+1 ) is M i+1 The coordinates of .

[0059] Step S4: Obtain the endpoints of the object contour on the cross-section line segment according to the colored point cloud set Q and add them to the cross-section data set B, and add object attribute labels to the cross-section points to obtain a new cross-section data set C. Specifically, the process of obtaining the cross-section data set B is as follows: After the point cloud is colored, the coordinates (X, Y, Z) of the object contour points can be directly selected through the point cloud software and the data can be recorded.

[0060] Step S5: Encrypt the adjacent points that do not meet the requirements according to the different scale requirements of the hydropower engineering measurement specifications and add them to the cross-section dataset C to form a new cross-section dataset D, wherein the recorded cross-section dataset D includes point numbers and coordinate information (X, Y, Z).

[0061] Step S6: Convert the final cross-section data set D into a cross-section mileage file, i.e., each point D on the cross-section line segment i(X, Y, Z) is converted to (mileage value, elevation value, attribute value). The calculation method of mileage value is as follows: looking downstream of the river, the mileage value of the left end point of the line segment is 0, and the attribute value of the left end point is marked; the mileage is accumulated to the right end point, the mileage value of the end point of the cross-section line segment is the length of the line segment, and the attribute value of the right end point is marked. The mileage value S of any point in the middle i :

[0062] Here, i takes values ​​of 1, 2, 3, etc.

[0063] Step S7, draw the mileage file as a cross-section diagram, and then generate the cross section of the river in the reservoir area. For example, the left end point of the cross-section line segment is taken as the origin, the direction of the cross-section line segment is the X axis, the elevation value is the Z axis, and the mileage value, elevation value, attribute value, cross-section name and other information are marked. When the length or relative height of the cross section in the same measurement area differs greatly, different scales can be selected.

[0064] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for fusing multi-source data and gradually encrypting and generating a river cross section in a reservoir area, characterized in that: The following steps are involved: Step S1, obtaining multi-source data of the river section in the reservoir area, and fusing the multi-source data to obtain a point cloud set Q; Step S2, laying out the cross-section line segments, and determining an initial cross-section data set A according to the laid out cross-section line segments, wherein the data set A includes the start point and end point data of the cross-section; Step S3, obtaining terrain feature points on the cross-section line segment, and adding them to the cross-section data set A to form a new cross-section data set B; Step S4, obtaining the endpoints of the object contour on the cross-section line segment according to the colored point cloud set Q and adding them to the cross-section data set B, and adding object attribute labels to the cross-section points to obtain a new cross-section data set C; Step S5, encrypting the cross-section points according to the cross-section spacing requirements of different scales required by the hydropower engineering survey specification to form a new cross-section data set D; Step S6: Convert the cross-section data set D into a cross-section mileage file, i.e., each point D on the line segment i (X, Y, Z) is converted to (mileage value, elevation value, attribute value) accordingly; Step S7: Draw the mileage file as a cross-section diagram, and then generate a river cross-section in the reservoir area.

2. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 1 is characterized in that: In step S1, the multi-source data includes point cloud data collected by airborne laser radar, river underwater elevation point data collected by unmanned boats, and artificial elevation point data collected by RTK.

3. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 2 is characterized in that: In step S1, the fusion process is as follows: The point cloud data collected by the airborne laser radar is processed by coloring, denoising, classification, and coordinate conversion to obtain a ground point cloud set R with RGB color in the engineering coordinate system; The river underwater elevation point data collected by unmanned boats and the artificial elevation point data collected by RTK in the acquired multi-source data are converted into an engineering coordinate system and converted into a point cloud file in las format, and merged into the point cloud set R to form a new point cloud set Q.

4. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 3 is characterized in that: The specific method of converting to las format is: first organize the river underwater elevation point data and artificial elevation point data into Excel table format, where the first column is the point number, the second column is the X coordinate under the engineering coordinate system, the third column is the Y coordinate under the engineering coordinate system, and the fourth column is the Z coordinate of the elevation value; after organizing, save the file as csv format, and then use the LasWrite function in MATLAB to write the las file.

5. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 4 is characterized in that: In step S3, the process of obtaining terrain feature points includes the following steps: Step S31, calculate the plane coordinates of the interpolation point Mn of the cross-section line segment: interpolate a point every distance λ from the starting point to the end point of the cross-section line segment, and the coordinates of the interpolation point are (Xn, Yn); Step S32, using the KD tree search method to search for the four points closest to the interpolation point Mn in the point cloud set Q, and calculating the elevation value Zn of the target point according to the inverse distance weighted interpolation method; Step S33: determine the terrain feature points on the cross-section line segment according to the change in terrain slope.

6. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 5 is characterized in that: In step S31, the method for calculating the plane coordinates of the interpolation point is: X n =X1+nλ(X2-X1) / L; Y n =Y1+nλ(Y2-Y1) / L; Among them, n is 1, 2, 3...; L is the length of the cross-section segment; (X1, Y1) is the starting point coordinate of the cross-section segment; (X2, Y2) is the end point coordinate of the cross-section segment.

7. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 6 is characterized in that: In step S32, the calculation process of the elevation value Zn includes the following steps: Step S321, using the KD tree search method to search for the four coordinate points in the point cloud set Q that are closest to the point Mn, namely Q1 (x1, y1, z1), Q2 (x2, y2, z2), Q3 (x3, y3, z3), and Q4 (x4, y4, z4); Step S322, calculate the Euclidean distance from point Mn to the four coordinate points: Step S323, setting a weight index p, and calculating a weight; wherein p=2; The weight of Q1 is: The weight of Q2 is: The weight of Q3 is: The weights of Q4 are: Step S324, calculate the elevation value Zn of the target point: <h2 style=";text-align:left;direction:ltr">Z<h2 style=";text-align:left;direction:ltr"> n <h2 style=";text-align:left;direction:ltr"> (W1Z1+W2Z2+W3Z3+W4Z4) / (W1+W2+W3+W4) 8. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 7 is characterized in that: In step S33, the determination process is: Get two adjacent points M i 、M i+1 , and calculate the adjacent points M i , M i+1 Slope θ i , the slope θ i Compared with the set slope threshold θ, if the slopes of two adjacent points θ i If the slope is greater than the slope threshold θ, both points are recorded as terrain feature points. The terrain feature points, the starting point and the end point together constitute a new cross-section data set B; in, In the formula, (X i ,Y i ,Z i ) is M i The coordinates of (X i+1 , Y i+1 , Z i+1 ) is M i+1 The coordinates of .

9. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 8 is characterized in that: In step S6, the mileage value is calculated as follows: When looking toward the downstream of the river, set the mileage value of the left end point of the cross-section line segment to 0, and mark the left end point of the attribute value; the mileage is accumulated toward the right end point, and the mileage value of the end point of the cross-section line segment is the length of the line segment, and the right end point of the attribute value is marked. The mileage value S of any point in the middle i :

10. The method for generating a reservoir river cross section by fusing multi-source data and encrypting it step by step according to claim 1 is characterized in that: In step S7, the drawing process is: take the left end point of the section line segment as the origin, the direction of the section line segment as the X-axis, the elevation value as the Z-axis, and mark the mileage value, elevation value, attribute value, and section name information.

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