A Method for Interpolating Topographic Elevation of Mountain Rivers Based on Sparse River Cross-Section Elevation Data

Abstract

This invention discloses a method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data. The method includes the following steps: Step 1, acquiring basic data of the target river and preprocessing it; Step 2, determining the direction of different cross-section lines; Step 3, creating new cross-section lines and calculating their length and latitude / longitude coordinates; Step 4, dividing the new cross-section lines to obtain cross-section points and resampling them; Step 5, obtaining the elevation data of each cross-section point on the new cross-section line; Step 6, obtaining the elevation data of the target river area. The method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data described in this invention can fully utilize existing elevation data, more accurately express the local topographic features of mountainous areas, achieve high-precision topographic elevation interpolation of mountain rivers, and provide a scientific basis for flood inundation analysis.

Description

Technical Field

[0001] This invention belongs to the field of flood inundation analysis technology, and in particular relates to a method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data. Background Technology

[0002] With the increasingly significant impacts of global climate change and the frequent occurrence of extreme weather events, mountain floods are particularly severe. Flood inundation analysis is of great importance for flood risk analysis, loss assessment, and protecting the lives and property of people in disaster-stricken areas. In flood inundation analysis, the accuracy of the digital elevation model (DEM) data directly affects the accuracy of the results; therefore, relatively precise elevation data, such as 1m resolution, is often required. However, currently available elevation data typically has a resolution of 30m or 90m, which is clearly insufficient for the needs of flood inundation analysis.

[0003] Currently, commonly used methods for elevation measurement include traditional leveling, trigonometric leveling, remote sensing satellite leveling, and UAV lidar leveling. Among these, leveling and trigonometric leveling are inefficient, labor-intensive, and cumbersome, and the results are often inaccurate due to the generally low skill level of field surveyors. Remote sensing satellite leveling is less accurate than planar coordinate measurement, and the measured geodetic height needs to be converted from the commonly used normal height, resulting in higher measurement costs. UAV lidar scanning systems are also prone to errors due to factors such as flight altitude, scanning angle, and external wind speed and air pressure, and are costly and difficult to apply in practice.

[0004] Currently used elevation interpolation methods include inverse distance weighted interpolation and Kriging interpolation. Their basic principle is to utilize the elevations of known sampling points within the search radius, assign different weights to these interpolation points, and then calculate the elevation of the point to be interpolated by weighted averaging. This interpolation method cannot fully utilize existing elevation data and cannot effectively represent local topographic features in mountainous areas. Especially when interpolating river cross-sections, it can cause the problem of river elevation homogenization, resulting in low interpolation accuracy. Therefore, how to achieve high-precision elevation interpolation of mountainous river topography is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data, so as to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention discloses a method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data. The method includes the following steps:

[0008] Step 1: Obtain and preprocess basic data of the target river channel: First, obtain basic data of the target river channel, including cross-sectional data and channel line data. The cross-sectional data includes the cross-section and cross-sectional line number, cross-section name, cross-sectional line start and end points, type of each sampling point in the cross-section, latitude and longitude coordinates of each sampling point in the cross-section, distance between the start and end points of each sampling point in the cross-section, and elevation. The cross-section and cross-sectional line numbers are arranged sequentially from upstream to downstream. The types of each sampling point in the cross-section include non-feature points and riverbank boundary points. The channel line data is a vector file of the channel line of the target river. The channel line is a broken line formed by connecting multiple channel points, and the direction of the channel line is the direction of the river, i.e., from upstream to downstream.

[0009] Then, the acquired basic data is preprocessed, including converting the latitude and longitude coordinates of each sampling point of the cross section into a unified coordinate system, and using linear interpolation to convert the resolution of the river line to a specified resolution, and dividing the river line into a series of river points with the same interval according to the specified resolution, denoted as R.

[0010] Step 2: Determine the direction of different cross-section lines: Take the i-th cross-section line as the starting cross-section line and the (i+1)-th cross-section line as the ending cross-section line, where i = 1, 2, ..., n, and n is the total number of river cross-section lines. Determine the direction of the starting cross-section line and the ending cross-section line respectively. If the starting cross-section line and the ending cross-section line are opposite in direction, then the direction of the starting cross-section line or the ending cross-section line needs to be reversed to make the two directions consistent.

[0011] Step 3: Create new cross-section lines and calculate their length and latitude / longitude coordinates: Let r be the series of river points R between the start and end cross-section lines; create a new cross-section line for each river point in r. Each new cross-section line contains five elements: the length L of the left cross-section line. 左 Length L of the right-side cross-section 右 The width of the river channel on the left is l 左 The width of the river channel on the right is l 右 The direction of the cross-section line, represented by the unit direction vector u; the length L of the right-side cross-section line. 右 The width of the channel on the right is obtained by linearly varying the lengths of the starting and ending cross-sections to the right of the channel line; the same applies to the left side. The right-side channel width is l. 右 The cross-section line is obtained by linearly changing the distance from the right bank boundary point of the starting cross-section line to the river channel line and the distance from the right bank boundary point of the ending cross-section line to the river channel line, and the same applies to the left side; the direction of the cross-section line is the direction of the unit direction vector u that gradually changes from the unit direction vector of the starting cross-section line to the unit direction vector of the ending cross-section line.

[0012] Iterate through the river point indices in r, take the j-th river point in r, j = 1, 2, ..., m, where m is the number of river points in r, and calculate the length of the new cross-section line:

[0013] L = L 左 +L 右 (1)

[0014] In the formula: L is the length of the new cross-section line;

[0015] Let points A, B, and C be the starting point, ending point, and river channel point of the new cross-section, respectively. Then, the formulas for calculating the coordinates of the starting and ending points of the new cross-section are:

[0016] X A =X C -(u*L 右 (2)

[0017] Y A =Y C -(u*L 右 (3)

[0018] X B =X C +(u*L 左 (4)

[0019] Y B =Y C +(u*L 左 (5)

[0020] In the formula: X A X B X C The longitude coordinates of points A, B, and C are respectively, Y = 1 / 2. A Y B Y C These are the latitude coordinates of points A, B, and C, respectively.

[0021] Step 4: Divide the new cross-section line to obtain cross-section points and resample: Based on the starting and ending coordinates of the newly created cross-section line, divide the new cross-section line at the specified resolution to obtain a series of cross-section points, and calculate the number of non-channel cross-section points on the right side, the number of non-channel cross-section points on the left side, and the number of channel cross-section points. The calculation process is as follows:

[0022] 1) Calculate the index positions of the right and left riverbank boundary points in the new cross-section coordinate point list:

[0023]

[0024] In the formula: I 右 I 左 These are the indexes for the right riverbank boundary and the left riverbank boundary, respectively.max The maximum index of the coordinate points of the new cross-section line;

[0025] 2) Calculate the number of non-river channel cross-section points on the right side of the new cross-section line, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points:

[0026] N 右 =I 右 (8)

[0027] N 左 =I max -I 左 (9)

[0028] N 河 =I max -N 左 -N 右 (10)

[0029] Where: N 右 N 左 N 河 These represent the number of non-river channel cross-section points on the right side of the new cross-section line, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points, respectively.

[0030] 3) Based on the number of non-river channel cross-section points on the right side, non-river channel cross-section points on the left side, and river channel cross-section points on the new cross-section line, resample the cross-section points of the corresponding categories on the starting and ending cross-section lines to ensure that the starting, ending, and new cross-section lines maintain consistency in the number of non-river channel cross-section points on the right and left sides, as well as the number of river channel cross-section points on the left and right sides.

[0031] Step 5: Obtain the elevation data of each cross-section point on the new cross-section line: The elevation of each cross-section point on the new cross-section line is obtained by inverse distance weighted interpolation. The calculation formula is as follows:

[0032]

[0033] In the formula: Z k For the elevation of each cross-section point on the new cross-section line, I 河 Here, M represents the index of the river point corresponding to the new cross-section line, and Z represents the number of river point indices. Fk Z Sk These are the elevations of each section point on the end section line and the beginning section line, respectively.

[0034] Step 6: Obtain elevation data of the target river channel area: Divide the target river channel area into grids according to the specified resolution. Some grids contain cross-section points with known elevations, while some grids do not contain elevation data. Use the nearest neighbor interpolation method, that is, the elevation of the grid is equal to the elevation of the nearest grid with elevation data. Finally, the elevation data of the entire target river channel area with the specified resolution can be obtained.

[0035] Furthermore, the specified resolution is 1m.

[0036] Furthermore, the unified coordinate system mentioned in step 1 is specifically the UTM series coordinate system.

[0037] Furthermore, the specific process of determining the direction of the start and end cross-section lines in step 2 is as follows: Taking the start and end cross-section lines as target cross-section lines respectively, find the river point closest to the target cross-section line from R. Using this river point as the starting point and the next river point as the ending point, construct a vector for the closest target river. Similarly, using the starting and ending points of the target cross-section line as the starting and ending points of the vector, construct a vector for the target cross-section line. Using the vector for the closest target river as the x-axis direction, rotating the x-axis counterclockwise by 90° as the y-axis direction, and using the starting point of the vector for the target cross-section line as the origin, construct a coordinate system. If the ending point of the vector for the target cross-section line falls in the first or second quadrant, it is positive; if it falls in the third or fourth quadrant, it is negative. If it is negative, the direction of the negative cross-section line needs to be reversed to ensure that the start and end cross-section lines are in the same direction, i.e., both are positive.

[0038] The beneficial effects of this invention are: the mountain river topographic elevation interpolation method based on sparse river channel cross-section elevation data can make full use of existing elevation data, more accurately express the local topographic features of mountainous areas, achieve high-precision mountain river topographic elevation interpolation, and provide a scientific basis for flood inundation analysis.

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the method flow described in this invention;

[0041] Figure 2 A schematic diagram illustrating the process of determining the direction of a river channel cross-section.

[0042] Figure 3 A schematic diagram of the process of creating a new cross-section of the river channel. Detailed Implementation

[0043] This invention discloses a method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data, such as... Figure 1 As shown, the method includes the following steps:

[0044] Step 1: Obtain basic data of the target river channel and perform preprocessing.

[0045] Acquire basic data for the target river channel, including cross-sectional data and channel line data. Cross-sectional data includes the cross-section and cross-sectional line number, cross-section name, start and end points of the cross-sectional line, type of each sampling point, latitude and longitude coordinates of each sampling point, distance between the start and end points of each sampling point, and elevation. Sampling point types include non-feature points and riverbank boundary points. In actual measurements, cross-sections and cross-sectional lines correspond one-to-one, with cross-section and cross-sectional line numbers arranged sequentially from upstream to downstream. Select the appropriate projection coordinate system based on the latitude and longitude of the sampling points and perform coordinate system transformation to a unified coordinate system; the UTM series coordinate system is most commonly used. Channel line data refers to the vector file of the target river channel. The channel line is a polyline formed by connecting multiple channel points, and its direction is the direction of the river, i.e., from upstream to downstream. Convert the resolution of the acquired channel line to a specified resolution (1m) using linear interpolation. Divide the channel line into a series of channel points at equal intervals according to the specified resolution (1m), denoted as R.

[0046] Step 2: Determine the direction of different cross-sectional lines.

[0047] Take the i-th cross-section line as the starting cross-section line and the (i+1)-th cross-section line as the ending cross-section line (i = 1, 2, ..., n, where n is the total number of river cross-section lines). Determine the direction of the starting and ending cross-section lines respectively. The determination process is as follows:

[0048] Using the start and end cross-section lines as target cross-section lines respectively, find the nearest river channel point in R to the target cross-section line. Using this river channel point as the starting point and the next river channel point as the ending point, construct a vector representing the nearest target river channel. Similarly, using the start and end points of the target cross-section line as the start and end points of a vector, construct a target cross-section line vector. Construct a coordinate system with the nearest target river channel vector as the x-axis, a 90° counterclockwise rotation of the x-axis as the y-axis, and the start point of the target cross-section line vector as the origin. If the end point of the target cross-section line vector falls in the first or second quadrant, it is considered positive; if it falls in the third or fourth quadrant, it is considered negative. If it is negative, the direction of the negative cross-section line needs to be reversed to ensure that the start and end cross-section lines are in the same direction, i.e., both are positive.

[0049] Figure 2 This diagram illustrates the direction determination of a river channel cross-section. (a) represents the forward direction, and (b) represents the reverse direction. A and B in the diagram are the start and end points of the river channel cross-section, respectively. These are the nearest target river channel vector and the target cross-section line vector, respectively. Figure 2 In (a), the endpoint of the target section line vector falls in the second quadrant, therefore it is positive; while Figure 2 (b) The endpoint of the target section line vector falls in the third quadrant, so it is in the opposite direction.

[0050] Step 3: Create a new profile line and calculate its length and latitude / longitude coordinates.

[0051] Let r be the series of river points R between the start and end cross-sections; create a new cross-section for each river point in r, and each new cross-section contains five elements: the length L of the left cross-section. 左 Length L of the right-side cross-section 右 The width of the river channel on the left is l 左 The width of the river channel on the right is l 右 The direction of the cross-section line (represented by the unit direction vector u) is based on the river channel line. The length L of the right-side cross-section line is... 右 The width of the channel on the right is obtained by linearly varying the lengths of the starting and ending cross-sections to the right of the channel line; the same principle applies to the left side. The channel width on the right is l. 右 The cross-section line direction is obtained by linearly varying the distances from the right bank boundary point of the starting cross-section line to the channel line, and vice versa for the ending cross-section line. The cross-section line direction is the direction of the unit direction vector u that gradually changes from the unit direction vector of the starting cross-section line to the unit direction vector of the ending cross-section line.

[0052] Iterate through the river point indices in r, take the j-th river point in r, j = 1, 2, ..., m, where m is the number of river points in r, and calculate the length of the new cross-section line:

[0053] L = L 左 +L 右 (1)

[0054] In the formula: L is the length of the new cross-section line.

[0055] Let points A, B, and C be the starting point, ending point, and river channel point of the new cross-section, respectively. The coordinates of the starting and ending points of the new cross-section are calculated as follows:

[0056] X A =X C -(u*L 右 (2)

[0057] Y A =Y C -(u*L 右 (3)

[0058] X B =X C +(u*L 左 (4)

[0059] Y B =Y C +(u*L 左 (5)

[0060] In the formula: X A XB X C The longitude coordinates of points A, B, and C are respectively, Y = 1 / 2. A Y B Y C These are the latitude coordinates of points A, B, and C, respectively.

[0061] like Figure 3 As shown in the diagram, to create a new cross-section line of a river channel, we find a series of river points R between the starting and ending cross-section lines, denoted as r; and create a new cross-section line for each river point in r. In the diagram, A and B are the starting and ending points of the river channel cross-section line, E and F are the left and right bank boundaries of the river channel cross-section line, the subscript S represents the starting cross-section line, the subscript F represents the ending cross-section line, and the subscript j represents the cross-section line created at the j-th river point between the starting and ending cross-section lines. That is: A S E S F S B S These represent the starting point, left bank boundary, right bank boundary, and ending point of the cross-section line, respectively. A j E j F j B j A represents the starting point, left bank boundary, right bank boundary, and ending point of the cross-section line created at the j-th river point, respectively. F E F F F B F These represent the starting point, left bank boundary, right bank boundary, and ending point of the section line, respectively.

[0062] Step 4: Divide the new cross-section line to obtain cross-section points and resample.

[0063] Based on the starting and ending coordinates of the new cross-section line created in the previous step, the new cross-section line is divided at a specified resolution (1m) to obtain a series of cross-section points. The number of non-river channel cross-section points on the right side, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points are calculated. The calculation method is as follows:

[0064] 1) Calculate the index positions of the right and left riverbank boundary points in the new cross-section coordinate point list:

[0065]

[0066] In the formula: I 右 I 左 These are the indexes for the right riverbank boundary and the left riverbank boundary, respectively. max This is the maximum index of the coordinate points of the new cross-section line.

[0067] 2) Calculate the number of non-river channel cross-section points on the right side of the new cross-section line, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points:

[0068] N 右 =I 右 (8)

[0069] N 左 =I max -I 左 (9)

[0070] N 河 =I max -N 左 -N 右 (10)

[0071] Where: N 右 N 左 N 河 These represent the number of non-river channel cross-section points on the right side of the new cross-section line, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points, respectively.

[0072] 3) Based on the number of non-river channel cross-section points on the right side, non-river channel cross-section points on the left side, and river channel cross-section points on the new cross-section line, resample the cross-section points of the corresponding categories on the starting and ending cross-section lines to ensure that the starting, ending, and new cross-section lines maintain consistency in the number of non-river channel cross-section points on the right and left sides, as well as the number of river channel cross-section points on the left and right sides.

[0073] Step 5: Obtain the elevation data of each cross-section point on the new cross-section line: The elevation of each cross-section point on the new cross-section line is obtained by inverse distance weighted interpolation. The calculation formula is as follows:

[0074]

[0075] In the formula: Z k For the elevation of each cross-section point on the new cross-section line, I 河 Here, M represents the index of the river point corresponding to the new cross-section line, and Z represents the number of river point indices. Fk Z Sk These are the elevations of each section point on the end section line and the beginning section line, respectively.

[0076] Step 6: Obtain the elevation data of the target river channel area.

[0077] The elevation data of the target river channel area is obtained using the nearest neighbor interpolation method. The nearest neighbor interpolation method, also known as natural nearest neighbor interpolation, selects the known elevation value closest to the point to be interpolated as the interpolation result. While simple to operate, this method is only suitable for situations where known elevation points are relatively densely packed; otherwise, distortion may occur. After the above steps, a sufficient number of cross-section lines and cross-section point elevations have been obtained, therefore, the nearest neighbor interpolation method can be used for interpolation.

[0078] The target river area is divided into grids with sides of 1m at a specified resolution (1m). Some grids contain cross-section points with known elevations, while others do not contain elevation data. The nearest neighbor interpolation method is used, that is, the elevation of the grid is equal to the elevation of the nearest grid with elevation data. Finally, the elevation data of the entire target river area at the specified resolution (1m) can be obtained.

[0079] Finally, it should be noted that the above description is only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred arrangement, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section elevation data, characterized in that, The method includes the following steps: Step 1: Obtain and preprocess basic data of the target river channel: First, obtain basic data of the target river channel, including cross-sectional data and channel line data. The cross-sectional data includes the cross-section and cross-sectional line number, cross-section name, cross-sectional line start and end points, type of each sampling point in the cross-section, latitude and longitude coordinates of each sampling point in the cross-section, distance between the start and end points of each sampling point in the cross-section, and elevation. The cross-section and cross-sectional line numbers are arranged sequentially from upstream to downstream. The types of each sampling point in the cross-section include non-feature points and riverbank boundary points. The channel line data is a vector file of the channel line of the target river. The channel line is a broken line formed by connecting multiple channel points, and the direction of the channel line is the direction of the river, i.e., from upstream to downstream. Then, the acquired basic data is preprocessed, including converting the latitude and longitude coordinates of each sampling point of the cross section into a unified coordinate system, and using linear interpolation to convert the resolution of the river line to a specified resolution, and dividing the river line into a series of river points with the same interval according to the specified resolution, denoted as R. Step 2: Determine the direction of different cross-section lines: Take the i-th cross-section line as the starting cross-section line and the (i+1)-th cross-section line as the ending cross-section line, where i = 1, 2, ..., n, and n is the total number of river cross-section lines. Determine the direction of the starting cross-section line and the ending cross-section line respectively. If the starting cross-section line and the ending cross-section line are opposite in direction, then the direction of the starting cross-section line or the ending cross-section line needs to be reversed to make the two directions consistent. Step 3: Create new cross-section lines and calculate their length and latitude / longitude coordinates: Let r be the series of river points R between the start and end cross-section lines; create a new cross-section line for each river point in r. Each new cross-section line contains five elements: the length L of the left cross-section line. 左 Length L of the right-side cross-section 右 The width of the river channel on the left is l 左 The width of the river channel on the right is l 右 The direction of the cross-section line, represented by the unit direction vector u; the length L of the right-side cross-section line. 右 The width of the channel on the right is obtained by linearly varying the lengths of the starting and ending cross-sections to the right of the channel line; the same applies to the left side. The right-side channel width is l. 右 The cross-section line is obtained by linearly changing the distance from the right bank boundary point of the starting cross-section line to the river channel line and the distance from the right bank boundary point of the ending cross-section line to the river channel line, and the same applies to the left side; the direction of the cross-section line is the direction of the unit direction vector u that gradually changes from the unit direction vector of the starting cross-section line to the unit direction vector of the ending cross-section line. Traverse the river point indices in r, take the j-th river point in r, j = 1, 2, ..., m, where m is the number of river points in r, and calculate the length of the new cross-section line: L=L 左 +L 右 (1) In the formula: L is the length of the new cross-section line; Let points A, B, and C be the starting point, ending point, and river channel point of the new cross-section, respectively. Then, the formulas for calculating the coordinates of the starting and ending points of the new cross-section are: X A =X C -(u*L 右 ) (2) AND A =Y C -(u*L 右 ) (3) X B =X C +(u*L 左 ) (4) AND B =Y C +(u*L 左 ) (5) In the formula: X A X B X C The longitude coordinates of points A, B, and C are respectively, Y... A Y B Y C These are the latitude coordinates of points A, B, and C, respectively. Step 4: Divide the new cross-section line to obtain cross-section points and resample: Based on the starting and ending coordinates of the newly created cross-section line, divide the new cross-section line at the specified resolution to obtain a series of cross-section points, and calculate the number of non-channel cross-section points on the right side, the number of non-channel cross-section points on the left side, and the number of channel cross-section points. The calculation process is as follows: 1) Calculate the index positions of the right and left riverbank boundary points in the new cross-section coordinate point list: In the formula: I 右 I 左 These are the indexes for the right riverbank boundary and the left riverbank boundary, respectively. max The maximum index of the coordinate points of the new cross-section line; 2) Calculate the number of non-river channel cross-section points on the right side of the new cross-section line, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points: N 右 =I 右 (8) N 左 =I max -I 左 (9) N 河 =I max -N 左 -N 右 (10) Where: N 右 N 左 N 河 These represent the number of non-river channel cross-section points on the right side of the new cross-section line, the number of non-river channel cross-section points on the left side, and the number of river channel cross-section points, respectively. 3) Based on the number of non-river channel cross-section points on the right side, non-river channel cross-section points on the left side, and river channel cross-section points on the new cross-section line, resample the cross-section points of the corresponding categories on the starting and ending cross-section lines to ensure that the starting, ending, and new cross-section lines maintain consistency in the number of non-river channel cross-section points on the right and left sides, as well as the number of river channel cross-section points on the left and right sides. Step 5: Obtain the elevation data of each cross-section point on the new cross-section line: The elevation of each cross-section point on the new cross-section line is obtained by inverse distance weighted interpolation. The calculation formula is as follows: In the formula: Z k For the elevation of each cross-section point on the new cross-section line, I 河 Here, M represents the index of the channel point corresponding to the new cross-section line, and Z represents the number of channel point indices. Fk Z Sk These are the elevations of each section point on the end section line and the beginning section line, respectively. Step 6: Obtain elevation data of the target river channel area: Divide the target river channel area into grids according to the specified resolution. Some grids contain cross-section points with known elevations, while other grids do not contain elevation data. For grids that do not contain elevation data, use the nearest neighbor interpolation method, that is, the grid elevation is equal to the elevation of the nearest grid with elevation data. Finally, the elevation data of the entire target river channel area with the specified resolution can be obtained.

2. The method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section point elevation data according to claim 1, characterized in that, The specified resolution is 1m.

3. The method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section point elevation data according to claim 1, characterized in that, The unified coordinate system mentioned in step 1 is specifically the UTM series coordinate system.

4. The method for interpolating the topographic elevation of mountain rivers based on sparse river cross-section point elevation data according to claim 1, characterized in that, The specific process of determining the direction of the start and end cross-section lines in step 2 is as follows: taking the start and end cross-section lines as target cross-section lines respectively, find the river point closest to the target cross-section line from R, and construct a nearest target river vector with the river point as the starting point and the next river point as the ending point; similarly, construct a target cross-section line vector with the starting point and ending point of the target cross-section line as the starting point and ending point of the vector respectively. Construct a coordinate system with the nearest target channel vector as the x-axis direction, the x-axis rotated 90° counterclockwise as the y-axis direction, and the starting point of the target cross-section line vector as the origin. If the endpoint of the target cross-section line vector falls in the first or second quadrant, it is positive; if it falls in the third or fourth quadrant, it is negative. If it is negative, the direction of the negative cross-section line needs to be reversed to ensure that the starting and ending cross-section lines are in the same direction, i.e., both are positive.

Images