CN115841512A - Method for calculating real area of complex earth surface - Google Patents
Method for calculating real area of complex earth surface Download PDFInfo
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Abstract
The invention discloses a method for calculating the real area of a complex earth surface, which comprises the following steps: acquiring vector boundaries and digital elevation model raster data of a research area and a peripheral area, wherein the raster data comprises a plurality of complete grids and incomplete grids; the real surface areas of all complete grids and incomplete grids are obtained through calculation, and then a new vector boundary is obtained; and cutting the new vector boundary to obtain the real surface area data of the research area. The method can be used for carrying out fine processing on the boundary part of the complex area, further improving the accuracy of the real area calculation result, and being beneficial to carrying out comprehensive analysis on the real area calculation result and other types of data (ecology, environment, weather, resources and the like).
Description
Technical Field
The invention belongs to the fields of ecology, topography and remote sensing science, and particularly relates to a method for calculating the real area of a complex earth surface.
Background
Area is an important parameter in the study of surface processes, including projected area and ground area. The projection area is based on a standard ellipsoid or an area calculated by using a projection map; the ground surface area is the area accumulated by elements behind the relief along the real surface of the earth, a certain difference exists between the two areas, and the ground surface area is often more valuable than the projected area.
The accurate area data is a data basis for actually measuring and calculating the earth surface form, and the accurate and efficient area calculation has important theoretical value and practical significance. The ground surface area is used as a basic variable in a plurality of scientific research fields such as natural resource estimation, biomass and carbon reserve calculation, landscape spatial pattern analysis, species diversity investigation, species distribution and population density prediction, ecological system service function assessment and the like, and the accuracy of the calculation result is improved, so that the estimation precision of a research object can be effectively improved, and the uncertainty of the research result can be obviously reduced.
The real earth surface is difficult to measure directly, early earth surface area calculation is mainly based on a contour map and a navigation sheet, but the method is greatly influenced by the accuracy of a topographic map, is low in calculation accuracy, is complicated and has large calculation amount. With the development of the digital technology, the digital elevation model is used for calculating the real surface area, and in the prior art, the digital elevation model in the coverage area of the research area is taken as a whole to be calculated and can be divided into two categories, namely irregular triangular mesh-based and regular square mesh-based. Based on the irregular triangulation network method, data points are connected into triangles according to a certain rule, and the whole area is expressed as a series of irregular triangulation networks; the model based on the regular square grid comprises a quadric surface method, a gradient model and a triangle model.
At present, the research on the real area of the complex earth surface is based on the precision comparison of different models of the thought. However, studies involving real-area parameters of complex surfaces often incorporate other types of data (ecological, environmental, meteorological, resources, etc.) that are mostly stored in a grid. In the above thought, the triangular mesh constructed based on the irregular triangular mesh method cannot be superposed and analyzed with the raster data, the model based on the regular square mesh is relatively rough in processing the boundary, and the precision is relatively low when the surface area of the region with the complicated boundary is calculated. Therefore, it is necessary to provide a method for calculating the real area of a complex ground surface based on the separate processing of a complete grid and an incomplete grid.
Disclosure of Invention
The invention aims to provide a method for calculating the real area of a complex earth surface, which is used for carrying out fine processing on the boundary part of a complex area, further improving the precision of the calculation result of the real area, and carrying out comprehensive analysis on the real area and other types of data (ecology, environment, weather, resources and the like) so as to solve the problems in the prior art.
In order to achieve the purpose, the invention provides a method for calculating the real area of a complex earth surface, which comprises the following steps:
acquiring vector boundaries and digital elevation model grid data of a research area and a peripheral area, wherein the grid data comprises a plurality of complete grids and incomplete grids;
the real surface areas of all complete grids and incomplete grids are obtained through calculation, and then a new vector boundary is obtained;
and cutting the new vector boundary to obtain the real surface area data of the research area.
Optionally, the process of calculating the real surface area of each complete grid includes: taking a complete grid as a central grid, and mutually connecting the central point of the complete grid with the central points of a plurality of adjacent complete grids to form a plurality of three-dimensional triangles; respectively calculating the side length and the half perimeter of each three-dimensional triangle so as to obtain the area of each three-dimensional triangle; and summing the areas of the three-dimensional triangles to obtain the real surface area of the complete grid.
Optionally, the process of calculating the side length of the three-dimensional triangle includes: acquiring the square of the height difference between the central points of the two complete grids corresponding to the side length and the square of the plane distance, wherein the root mean square of the sum of the square of the height difference and the square of the plane distance is the side length;
the calculation process of the area of the three-dimensional triangle comprises the following steps: performing difference processing on the half perimeter of the three-dimensional triangle and the three side lengths respectively to obtain a first difference value, a second difference value and a third difference value; the root mean square of the product of the half perimeter and the first difference, the second difference and the third difference is the area of the three-dimensional triangle.
Optionally, the process of extracting the incomplete grid of the research area includes: temporarily creating raster mask data which is consistent with the raster data in resolution and is coincident with the raster center according to the vector boundary, and assigning a non-null value to the raster mask data; and performing operation processing on the raster mask data and input raster data, outputting null value raster in the raster mask data as null values, giving input raster values of corresponding positions to non-null value raster in the output, and obtaining the output raster data which is all the extracted incomplete raster data.
Optionally, the calculation process of the real surface area of each incomplete grid includes: and acquiring the vertical projection area and the surface roughness of the incomplete grid, wherein the product of the vertical projection area and the surface roughness is the real surface area of the incomplete grid.
Optionally, the calculation process of the vertical projection area of the incomplete grid includes: converting the incomplete grid data into a mesh polygon, and performing intersection operation with the vector boundary of the research region to obtain a polygon element of the research region, wherein the area of the polygon element is the vertical projection area of the incomplete grid;
and the ratio of the real surface area of the complete grid corresponding to the incomplete grid to the vertical projection area is the surface roughness of the incomplete grid.
Optionally, the process of acquiring the data of the real surface area of the research region includes: embedding the ground surface real area data of the incomplete grid into the ground surface real area data of the complete grid to obtain the ground surface real area data of the research region and the peripheral region thereof; and adjusting the vector boundary of the research region into a new vector boundary completely containing the incomplete grid, and cutting the ground surface real area data larger than the research region based on the new vector boundary to obtain the ground surface real area data of the research region.
The invention has the technical effects that:
the invention provides a method for calculating the real area of a complex earth surface based on the separate processing of a complete grid and an incomplete grid, which can be used for finely processing the boundary part of a complex area, further improving the precision of the calculation result of the real area and being beneficial to the comprehensive analysis of other types of data (ecology, environment, weather, resources and the like).
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, are included to provide a further understanding of the application, and the description of the exemplary embodiments of the application are intended to be illustrative of the application and are not intended to limit the application. In the drawings:
fig. 1 is a flowchart of a method for calculating a real area of a complex earth surface according to an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than presented herein.
Example one
As shown in fig. 1, the present embodiment provides a method for calculating a real area of a complex ground surface, which takes the calculation of a real area of a complex ground surface in a transected mountain area with a complex terrain and severe relief as an example.
Southeastern of Qinghai-Tibet plateau at transection mountain area, between 25 ° 33'-34 ° 17' N,91 ° 28'-104 ° 28' E, and total area of about 57 km 2 The highest altitude in the interior is 778m, the lowest altitude is 143m, and the average altitude is about 4000 m.
And acquiring vector boundary data and digital elevation model raster data of a transverse mountain area and a peripheral area thereof, wherein the range of the digital elevation model raster data is slightly larger than that of the vector boundary data in order to ensure the accuracy of calculation of the real surface area of the boundary part of the research area.
Calculating the real surface area of the complete grid in the transection mountain area and the peripheral area
The method of calculating the real area of the earth's surface for each complete grid is as follows:
(1) And taking the complete grid as a central grid, and mutually connecting the central point of the complete grid with the central points of 8 adjacent complete grids to form 8 three-dimensional triangles.
(2) And respectively calculating the side length of each three-dimensional triangle, wherein the side length is the root mean square of the sum of the square of the height difference between the two grid central points and the square of the plane distance between the two grid central points.
(3) And respectively calculating the semi-perimeter of each three-dimensional triangle, wherein the semi-perimeter is half of the sum of the three side lengths of the three-dimensional triangles.
(4) And respectively calculating the area of each three-dimensional triangle, wherein the area is the root mean square of the product of the half perimeter and the difference between the half perimeter and the three side lengths.
(5) And calculating the real surface area of the complete grid, wherein the real surface area is one fourth of the sum of the areas of the 8 surrounding three-dimensional triangles.
And (5) repeating the steps (1) to (5) to complete the calculation of the real area of the complex ground surface of all complete grids in the transverse mountain area and the peripheral area.
Extracting incomplete grids in a transected mountain area
If the vector boundary line of the transverse mountain area is located in a certain grid, the boundary line can be regarded as the boundary line passing through the grid, the grid through which the boundary line passes must be an incomplete grid, and the extraction of the incomplete grid can be realized by extracting all the grids through which the vector boundary line of the transverse mountain area passes, wherein the specific method comprises the following steps:
the input raster data of the horizontal mountain area and the peripheral area of the horizontal mountain area are extracted by using a vector boundary mask of the horizontal mountain area, raster mask data which is consistent with the resolution of the raster data and is overlapped with the center of the raster is temporarily created according to the vector boundary in the execution process, non-null values are assigned to the raster mask data, the raster mask and the input raster are subjected to AND operation, if null value raster exists, the null value is output, the input raster value of the corresponding position is assigned to the non-null value raster in the raster mask in the output, and the output raster data is all the extracted incomplete raster data which keeps the original values of the digital elevation model.
Calculating the real area of the incomplete grid ground surface in the cross-cut mountain area
The method of calculating the real area of the earth's surface for each incomplete grid is as follows:
(1) And calculating the surface roughness of the incomplete grid, wherein the surface roughness is the ratio of the real surface area of the complete grid corresponding to the incomplete grid to the vertical projection area.
(2) And converting the incomplete grid data into a mesh polygon and performing intersection operation with the vector boundary of the research area to obtain the polygon elements of the research area, and calculating the area of the polygon elements, namely the vertical projection area of the incomplete grid.
(3) And calculating the real surface area of the incomplete grid, wherein the real surface area is the product of the projection area of the incomplete grid and the surface roughness.
And (4) repeating the steps (1) to (3) to complete the calculation of the real area of the complex ground surface of all incomplete grids in the transverse mountainous area.
Calculating the real area of the ground surface of the transected mountain area
And embedding the real ground surface area data of the incomplete grids in the transverse mountain area into the real ground surface area data of the complete grids in the transverse mountain area and the peripheral area thereof to obtain the real ground surface area data of the transverse mountain area and the peripheral area thereof. And adjusting the vector boundary of the transverse mountain area into a new boundary completely containing incomplete grids, cutting the data of the real ground surface area with the range larger than that of the transverse mountain area through the new boundary to obtain the data of the real ground surface area of the transverse mountain area, and further calculating to obtain the ground surface roughness (real ground surface area/grid area) of the transverse mountain area.
In this embodiment, the real area of the complex ground surface of the mountain crossing is calculated by using the vector boundary diagram of the mountain crossing and the ASTERGDEMV2 digital elevation model data with the spatial resolution of 30 meters, and it should be noted that the method of this embodiment is also applicable to calculating the real area of the complex ground surface of different areas by using other digital elevation model data with different resolutions, such as the SRTMV4.1 data with the resolution of 90m, the GMTED2010 data with the resolutions of 250m and 1km, and the like.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (7)
1. A method for calculating the real area of a complex earth surface is characterized by comprising the following steps:
acquiring vector boundaries and digital elevation model grid data of a research area and a peripheral area, wherein the grid data comprises a plurality of complete grids and incomplete grids;
the real surface areas of all the complete grids and the incomplete grids are obtained through calculation, and then a new vector boundary is obtained;
and cutting the new vector boundary to obtain the real surface area data of the research area.
2. The method for calculating the real area of the complex earth surface according to claim 1,
the calculation process of the real surface area of each complete grid comprises the following steps: taking a complete grid as a central grid, and mutually connecting the central point of the complete grid with the central points of a plurality of adjacent complete grids to form a plurality of three-dimensional triangles; respectively calculating the side length and the half perimeter of each three-dimensional triangle so as to obtain the area of each three-dimensional triangle; and summing the areas of the three-dimensional triangles so as to obtain the real surface area of the complete grid.
3. The method for calculating the real area of the complex earth surface according to claim 2,
the calculation process of the side length of the three-dimensional triangle comprises the following steps: acquiring the square of the height difference and the square of the plane distance between the two complete grid central points corresponding to the side length, wherein the root mean square of the sum of the square of the height difference and the square of the plane distance is the side length of the three-dimensional triangle;
the calculation process of the area of the three-dimensional triangle comprises the following steps: performing difference processing on the half perimeter of the three-dimensional triangle and the three side lengths respectively to obtain a first difference value, a second difference value and a third difference value; the root mean square of the product of the half perimeter and the first difference, the second difference and the third difference is the area of the three-dimensional triangle.
4. The method for calculating the real area of the complex earth surface according to claim 1,
the process of extracting an incomplete grid of the study area includes: temporarily creating raster mask data which is consistent with the raster data in resolution and is coincident with the raster center according to the vector boundary, and assigning a non-null value to the raster mask data; and performing operation processing on the raster mask data and input raster data, outputting null value raster in the raster mask data as null values, giving input raster values of corresponding positions to non-null value raster in the output, and obtaining the output raster data which is all the extracted incomplete raster data.
5. The method for calculating the real area of the complex earth surface according to claim 1,
the calculation process of the real surface area of each incomplete grid comprises the following steps: and acquiring the vertical projection area and the surface roughness of the incomplete grid, wherein the product of the vertical projection area and the surface roughness is the real surface area of the incomplete grid.
6. The method for calculating the real area of the complex earth surface according to claim 5,
the calculation process of the vertical projection area of the incomplete grid comprises the following steps: converting the incomplete grid data into a mesh polygon, and performing intersection operation with the vector boundary of the research region to obtain a polygon element of the research region, wherein the area of the polygon element is the vertical projection area of the incomplete grid;
and the ratio of the real surface area of the complete grid corresponding to the incomplete grid to the vertical projection area is the surface roughness of the incomplete grid.
7. The method for calculating the real area of the complex earth surface according to claim 1,
the process of acquiring the real surface area data of the research area comprises the following steps: embedding the ground surface real area data of the incomplete grid into the ground surface real area data of the complete grid to obtain the ground surface real area data of the research region and the peripheral region thereof; and adjusting the vector boundary of the research region into a new vector boundary completely containing the incomplete grid, and cutting the ground surface real area data larger than the research region based on the new vector boundary to obtain the ground surface real area data of the research region.
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| CN116680871A (en) * | 2023-05-11 | 2023-09-01 | 中国科学院空天信息创新研究院 | Global background radiation data and abundance acquisition method, device and equipment |
| CN116680871B (en) * | 2023-05-11 | 2024-03-12 | 中国科学院空天信息创新研究院 | Global background radiation data and abundance acquisition method, device and equipment |
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