OSGB data-based ground surface exposed mountain fine stratum modeling method
Through the fine stratigraphic modeling method based on OSGB data, the HRBF implicit function is used to cut the mountain, which solves the problem of fineness and accuracy in complex landform modeling, and achieves high-precision stratigraphic modeling effect.
Patent Information
- Application Number
- CN202510144728.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2025-05-30
AI Technical Summary
When existing three-dimensional geological modeling technology faces complex landforms such as Danxia landforms, it is difficult to achieve high-resolution fine characterization, and there are topological errors in large-scale OSGB data, which hinders the application of implicit modeling methods.
A fine stratigraphic modeling method for surface exposed mountains based on OSGB data is proposed. By obtaining the target scene map and triangular network information, an initial mountain mesh is constructed, and the initial mountain mesh is cut from top to bottom layer by top to bottom through the HRBF implicit function to obtain multiple stratigraphic mesh, and finally the cross-sectional triangular mesh of each strata is constructed.
The fine stratigraphic modeling of complex landforms is realized, which significantly improves the fineness and accuracy of the model, and solves the limitations in OSGB data processing and model accuracy.
Smart Images
Figure CN120070787A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of mountain landform model construction, in particular to a method for fine stratum modeling of surface exposed mountains based on OSGB data. Background Art
[0002] With the advancement of geographic information technology, traditional modeling methods face many challenges in the three-dimensional fine depiction of complex landforms such as Danxia landform. Conventional three-dimensional geological modeling techniques are usually aimed at simple geological conditions. These methods are often insufficient in the detailed representation of complex landforms, affecting the accurate expression of landform features. The OSGB data format has been widely used in fields that require fine depiction, such as urban buildings and surface landforms, due to its efficient storage and excellent visualization capabilities as well as its oblique photogrammetry method.
[0003] The current 3D geological modeling technology is mainly divided into explicit and implicit methods. Explicit modeling often uses parameterized surfaces and gridding technologies, such as TIN modeling and contour line methods; implicit modeling uses mathematical functions to express the continuity of landforms, and typical methods include implicit distance fields and radial basis functions (RBF). When facing increasingly large amounts of high-resolution landform data, traditional 3D geological modeling technology still faces challenges.
[0004] Explicit 3D geological modeling is a WYSIWYG 3D geological modeling method. Faced with the huge amount of OSGB data interaction, the model's later verification and interactive correction make the modeling efficiency low. Implicit 3D geological modeling method calculates the implicit equation of the isosurface representing the geometric shape of the geological body and uses a series of implicit function visualization methods to establish a 3D geological model. Its modeling generally uses surface DEM data to express the ground morphology, which is feasible when low-resolution modeling is required. However, when facing the high-resolution modeling requirements of complex landforms such as Danxia landform, DEM is difficult to fully show the subtle changes in complex landform features. Therefore, it is necessary to replace DEM with higher-precision OSGB data to express the surface morphology. However, large-scale OSGB data often have a large number of topological errors, and the complex mountain features of Danxia landforms also represent that the ground surface often has multi-value situations. This also hinders the application of implicit modeling methods on OSGB data. Therefore, in the face of the demand for efficient and accurate modeling in modern geological research, new technical solutions are urgently needed to overcome the limitations of existing methods in data processing and model accuracy, so as to achieve a fine description of complex geological landforms. Summary of the invention
[0005] In view of the shortcomings of the prior art, the present invention aims to propose a method for fine stratigraphic modeling of surface exposed mountains based on OSGB data, comprising:
[0006] Step 1: Obtain a target scene map containing the outcropping mountain on the surface and the triangular mesh information of the outcropping mountain in the target scene map. The triangular mesh information includes the three-dimensional coordinates of the three vertices in the triangular mesh.
[0007] Step 2: Construct an initial mountain mesh according to the triangular mesh information.
[0008] Step 2.1: Load the triangular mesh information of the outcropping mountain on the surface in the target scene map. According to the triangular mesh information, determine the boundary lines of the tiles of the outcropping mountain on the surface in the target scene map. There is a gap between two adjacent tiles; and divide the tiles in the target scene map according to the boundary lines of the tiles to obtain a plurality of tile data. The tile data includes the three-dimensional coordinates of the three vertices of the triangular mesh in the tile, the connection relationship of the three vertices of the triangular mesh in the tile, and the three-dimensional coordinates of the vertices on the boundary line.
[0009] Step 2.2: Adjust the boundaries of adjacent tiles so that all adjacent tiles are connected to obtain a first triangular mesh of the outcropping mountain on the surface.
[0010] Step 2.3: Correct the first triangular mesh to obtain a target triangular mesh.
[0011] Step 2.4: According to the target triangular mesh, determine the boundary of the outcropping mountain on the surface in the target scene map to obtain a first three-dimensional boundary contour line of the outcropping mountain on the surface. Adjust the vertical coordinates of each point in the three-dimensional coordinates on the first three-dimensional boundary contour line to a preset height value to obtain a second three-dimensional boundary contour line. Connect the points on the first three-dimensional boundary contour line and the points on the second three-dimensional boundary contour line to construct triangles to obtain a mountain side mesh. The target triangular mesh and the mountain side mesh form an initial mountain mesh.
[0012] Step 3: Based on the stratigraphic layering information of the outcropping surface mountain, use the HRBF implicit function surface to cut the initial mountain mesh layer by layer from top to bottom to obtain a plurality of stratigraphic meshes, and reconstruct the stratigraphic meshes to obtain a boundary line segment list.
[0013] Step 3.1: Extract the stratigraphic layering information based on the outcropping part of the surface mountain. The stratigraphic layering information includes the stratigraphic boundary line between two strata and the stratigraphic attributes of each stratum.
[0014] Step 3.2: Take the points on the stratigraphic boundary line as implicit points, and assign the feature vector of each point to the vertical upward vector v(0, 0, 1). For each stratigraphic boundary line, calculate its HRBF implicit function surface.
[0015] Step 3.3: Arrange the HRBF implicit function surfaces of all formation boundaries in the order from top to bottom of the formations. Based on the triangle and implicit surface intersection algorithm, cut the initial mountain grid through the HRBF implicit function surfaces to obtain multiple formation grids. At the same time, add the attributes of the formations to the corresponding formation grids. For each formation grid, add points and edges on the boundary line after the formation grid is cut, construct triangles to obtain a new mountain side grid, and store the coordinates of the added points and edges to obtain a boundary line segment list;
[0016] Step 4: Construct the cross-section triangular grids of each formation, and then obtain the formation models of all formations;
[0017] Step 4.1: Based on the obtained boundary line segment list, use the bidirectional proximity search method to obtain a set of contour line polygons. The set of contour line polygons includes multiple polygon contour lines. The polygon contour line refers to the contour line obtained from a top-down perspective for each formation grid after the cutting is completed;
[0018] Step 4.2: Determine the inclusion relationship between the polygon contour lines in the set of contour line polygons. According to the inclusion relationship between the polygon contour lines, take the polygon contour lines not included by other polygon contour lines as the outer rings. From the outer rings inward, obtain two adjacent polygon contour lines with an inclusion relationship, and form multiple target contour lines by combining the two adjacent polygon contour lines with an inclusion relationship, as well as independent contour lines that do not include other polygon contour lines and are not included by other polygon contour lines;
[0019] Step 4.3: For multiple target contour lines and independent contour lines, construct triangles for them to obtain the cross-section triangular grids of each target contour line or independent contour line, and then obtain the cross-section triangular grids of all target contour lines or independent contour lines. For each formation, the cross-section triangular grids of all target contour lines or independent contour lines of the formation and the new mountain side grid form the formation model of the formation, and then obtain the formation models of all formations.
[0020] Optionally, Step 1 specifically includes:
[0021] Obtain the OSGB data of the surface-exposed mountain body. The OSGB data contains multiple scene graphs. In each scene graph, extract vertex data, and at the same time obtain index information. The index information includes the connection relationship between vertices. According to the vertex data and index information, construct a triangular mesh for the surface-exposed mountain body in each scene graph. According to requirements, select one scene graph as the target scene graph from the scene graphs with the triangular mesh constructed, and obtain the triangular mesh information corresponding to the surface-exposed mountain body in the target scene graph.
[0022] Optionally, Step 2.2 specifically includes:
[0023] For two adjacent tiles, calculate the distance between the vertices on the adjacent boundary lines of the two adjacent tiles according to the vertex coordinates on the adjacent boundary lines. When the distance between the vertices is less than a preset threshold, move the vertex on one boundary line to the position of the vertex on the other boundary line, and adjust the vertices on the adjacent boundary lines of all adjacent tiles to obtain an initial triangular mesh. For the vertices on the boundary lines in the initial triangular mesh that have not been processed, add new vertices to the sides of the triangles adjacent to the vertices, and construct triangles with the unprocessed vertices. Adjust the unprocessed vertices on the adjacent boundary lines of all adjacent tiles to obtain a first triangular mesh.
[0024] Optionally, step 2.3 specifically includes:
[0025] For each vertex in the first triangular mesh, calculate the normal vector distribution of the vertex and the adjacent triangles to obtain the normal vector of the vertex. Calculate the angle between the normal vectors of two adjacent vertices. If the angle between the normal vectors of two adjacent vertices is less than or equal to the preset threshold, no adjustment is required. If the angle between the normal vectors of two adjacent vertices is greater than the preset threshold, mark the triangular region where the two vertices are located as a non-popular region. For all vertices in the non-popular region, use the Laplace smoothing method to adjust the vertex coordinates. After correcting the coordinates of all vertices in the non-popular region, obtain the target triangular mesh.
[0026] Optionally, for all vertices in the non-popular region in step 2.3, use the Laplace smoothing method to adjust the vertex coordinates, which is implemented through the following formula:
[0027]
[0028] Among them, Adj i (P) represents the three-dimensional coordinates of vertex P in the non-popular region, U(p) represents the three-dimensional coordinates of vertex P after update, and n represents the number of vertices connected to vertex P in the non-popular region.
[0029] Optionally, step 3.2 is specifically implemented through the following formula:
[0030]
[0031] Among them, α i ∈R, β i ∈R 3 are undetermined coefficients of the implicit function; x j represents the jth implicit point, x i represents the ith implicit point; f(x j ) represents the function value obtained by substituting the jth implicit point into the implicit function; represents the partial derivative value obtained by substituting the jth implicit point into the implicit function; is a radial basis function, where represents the distance from the j-th implicit point to the i-th implicit point; represents the partial derivative of the radial basis function, H is the Hess calculation factor; v j is the feature vector of the j-th point; n is the number of implicit points.
[0032] Optionally, in step 4.3, for multiple target contour lines and independent contour lines, triangles are constructed for them to obtain the cross-sectional triangular mesh of each target contour line or independent contour line, including:
[0033] For each target contour line or independent contour line, on each target contour line or independent contour line, three points are selected, and the three-dimensional coordinates p 1 , p 2 , p 3 are obtained, and two edge vectors v 1 = p 2 - p 1 , v 2 = p 3 - p 2 are calculated, and then the cross product of the two edge vectors n = v 1 × v 2 is calculated. When the z-component of the cross product is greater than 0, a triangle is constructed based on these three points. When the z-component of the cross product is not greater than 0, three points are reselected on each target contour line or independent contour line to obtain the cross-sectional triangular mesh of each target contour line or independent contour line.
[0034] The beneficial effects of adopting the above technical solutions are as follows:
[0035] The present invention uses higher-precision OSGB data to replace DEM to represent the surface morphology. First, based on the OSG library, the data of the study area is mined at multiple levels and the explicit triangular mesh information is exported. Then, topological correction is performed on this large-scale complex mesh, including non-connection between tiles and reconstruction of non-popular meshes within tiles using the Laplace smoothing method. For the stratigraphic layering information of the mountain body, in the form of implicit function expression, the HRBF implicit function is solved for the stratigraphic layering information extracted from the outcropping part of the mountain body, and the implicit three-dimensional geological interface function of the mountain body strata is constructed. Then, the mountain body is cut by the implicit surface cutting triangle algorithm, and through steps such as determining the inclusion relationship of the contour line and generating the cross-section by the ear-cutting method, the cut mesh is closed to obtain the final stratigraphic model. The present invention uses high-precision OSGB data to replace traditional DEM data for surface morphology expression, and through innovative methods and steps, realizes fine stratigraphic modeling of complex landforms. Through the modeling method combining explicit and implicit, especially the topological correction of large-scale OSGB data, the application of implicit functions, and the optimization of the cutting algorithm, the fineness and accuracy of the model are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 It is a schematic flowchart of a method for fine stratigraphic modeling of an outcropping mountain body on the surface based on OSGB data in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0037] The following combines the drawings and embodiments to further describe in detail the specific embodiments of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.
[0038] Aiming at the problems existing in the prior art, the present invention provides a method for fine stratigraphic modeling of an outcropping mountain body on the surface based on OSGB data, combined with Figure 1 , which may include the following steps:
[0039] Step 1: Obtain a target scene map containing the outcropping mountain body on the surface and the triangular mesh information of the outcropping mountain body in the target scene map, where the triangular mesh information includes the three-dimensional coordinates of the three vertices in the triangular mesh;
[0040] Specifically, obtain the OSGB data of the outcropping mountains on the ground surface. The OSGB data contains multiple scene graphs. In a specific implementation, use the API provided by the OSG library to load the OSGB file, and read the OSGB data through the osgDB::readNodeFile function. When reading the OSGB data, verify whether the OSGB file is successfully loaded. Specifically, in the case where the data in the OSGB file cannot be read, it indicates that the file loading fails, and return to reload the OSGB file; in the case where the data in the OSGB file can be read, it indicates that the file loading is successful, and obtain the OSGB data. More specifically, for whether the OSGB file is successfully loaded, it can be verified by checking whether the smart pointer pointing to the osg::Node returned by the function is null, and using dynamic_cast to confirm whether the loaded node is of the expected type (osg::Group) and other methods.
[0041] Use the defined osg::NodeVisitor method to implement recursive traversal of the scene graph. In each scene graph, that is, extract vertex data from each osg::Geometry object, and at the same time obtain index information. Among them, the index information is stored in osg::DrawElements, and the index information includes the connection relationship between vertices. According to the vertex data and index information, construct a triangular mesh for the outcropping mountains on the ground surface in each scene graph. According to requirements, in the scene graph after constructing the triangular mesh, select one scene graph as the target scene graph, obtain the triangular mesh information corresponding to the outcropping mountains on the ground surface in the target scene graph, and export the triangular mesh information as a file in a specified format, with one line storing the data of one triangle. The specific format is: x1,y1,z1;x2,y2,z2;x3,y3,z3. Among them, x1,y1,z1 are the three-dimensional coordinates of the first vertex of the triangle, x2,y2,z2 are the three-dimensional coordinates of the second vertex of the triangle, and x3,y3,z3 are the three-dimensional coordinates of the third vertex of the triangle.
[0042] Step 2: Construct an initial mountain body mesh according to the triangular mesh information;
[0043] Step 2.1: Load the triangular mesh information of the outcropping mountains on the ground surface in the target scene graph. According to the triangular mesh information, determine the boundary lines of the tiles of the outcropping mountains on the ground surface in the target scene graph. Among them, there is an interval between two adjacent tiles; and divide the tiles in the target scene graph according to the boundary lines of the tiles to obtain multiple tile data {T 1 ,T 2 ,T 3 ,…}, and the tile data contains the three-dimensional coordinates of the three vertices of the triangular mesh in the tile, as well as the connection relationship of the three vertices of the triangular mesh in the tile, and the three-dimensional coordinates of the vertices on the boundary line;
[0044] It should be noted that after step 1 is completed, in step 2, it switches to another project for execution. Therefore, vertices are required. In specific implementation, the boundary vertices and edges of each tile are identified. A hash table is used to add index information to the spatial grid to quickly detect and pair the unconnected edges of adjacent tiles.
[0045] Step 2.2: Adjust the boundaries of adjacent tiles so that all adjacent tiles are connected to obtain a first triangular mesh of the exposed mountain body on the ground surface;
[0046] Specifically, for two adjacent tiles, according to the vertex coordinates on the adjacent boundary lines of the two adjacent tiles, calculate the distance between the vertices on the two adjacent boundary lines. When the distance between the vertices is less than the preset threshold, move the vertex on one boundary line to the position of the vertex on the other boundary line. Adjust the vertices on the adjacent boundary lines of all adjacent tiles to obtain an initial triangular mesh. For the vertices on the boundary lines in the initial triangular mesh that have not been processed, add new vertices to the sides of the triangles adjacent to the vertices and construct triangles with the unprocessed vertices. Adjust the unprocessed vertices on the adjacent boundary lines of all adjacent tiles to obtain the first triangular mesh.
[0047] Step 2.3: Correct the first triangular mesh to obtain the target triangular mesh;
[0048] Specifically, for each vertex in the first triangular mesh, calculate the normal vector distribution of the vertex and the adjacent triangles to obtain the normal vector of the vertex. Calculate the angle between the normal vectors of two adjacent vertices. If the angle between the normal vectors of two adjacent vertices is less than or equal to the preset threshold, no adjustment is required. If the angle between the normal vectors of two adjacent vertices is greater than the preset threshold, mark the triangular region where the two vertices are located as a non-popular region. For all vertices in the non-popular region, use the Laplace smoothing method to adjust the vertex coordinates. After correcting the coordinates of all vertices in the non-popular region, the target triangular mesh is obtained.
[0049] Among them, for all vertices in the non-popular region, use the Laplace smoothing method to adjust the vertex coordinates, which is achieved through the following formula:
[0050]
[0051] Among them, Adj i (P) represents the three-dimensional coordinates of vertex P in the non-popular region, U(p) represents the three-dimensional coordinates of vertex P after update, and n represents the number of vertices connected to vertex P in the non-popular region.
[0052] Step 2.4: According to the target triangular mesh, determine the boundary of the outcropping mountain body in the target scene graph, obtain the first three-dimensional boundary contour line of the outcropping mountain body, adjust the vertical coordinates of each point on the first three-dimensional boundary contour line to a preset height value to obtain the second three-dimensional boundary contour line, connect the points on the first three-dimensional boundary contour line and the points on the second three-dimensional boundary contour line to construct triangles, and obtain the mountain side mesh. The target triangular mesh and the mountain side mesh form the initial mountain mesh;
[0053] Among them, the preset height value is the specified height value during modeling.
[0054] Step 3: Based on the stratigraphic layering information of the outcropping surface mountain body, use the HRBF (Hermite Radial Basis Function) implicit function surface to cut the initial mountain mesh layer by layer from top to bottom to obtain multiple stratigraphic meshes, and reconstruct the stratigraphic meshes to obtain a list of boundary line segments;
[0055] Step 3.1: Based on the outcropping part of the surface mountain body, extract the stratigraphic layering information, and the stratigraphic layering information includes the stratigraphic boundary line between two strata and the stratigraphic attributes of each stratum;
[0056] In the specific implementation process, artificially delimit a better outcropping area, and use the real information (i.e., real color information) of the osgb model and the regional stratigraphic standard to manually extract the stratigraphic boundary line and judge the stratigraphic attributes.
[0057] Step 3.2: Take the points on the stratigraphic boundary line as implicit points, and assign the feature vector of each point to the vertically upward vector v(0, 0, 1). For each stratigraphic boundary line, calculate its HRBF implicit function surface, which is specifically implemented through the following formula:
[0058]
[0059] Among them, α i ∈R, β i ∈R 3 are undetermined coefficients of the implicit function; x j represents the jth implicit point, and x i represents the ith implicit point; f(x j ) represents the function value of the jth implicit point substituted into the implicit function; represents the partial derivative value of the jth implicit point substituted into the implicit function; is the radial basis function, among which, represents the distance from the jth implicit point to the ith implicit point; represents the partial derivative of the radial basis function, H is the Hess calculation factor; v j is the feature vector of the jth point; n is the number of implicit points.
[0060] Step 3.3: Arrange the HRBF implicit function surfaces of all formation boundaries in the order from top to bottom of the formations. Based on the triangle and implicit surface intersection algorithm, cut the initial mountain grid through the HRBF implicit function surfaces to obtain multiple formation grids. At the same time, add the attributes of the formations to the corresponding formation grids. For each formation grid, add points and edges on the boundary line after the formation grid is cut, construct triangles to obtain a new mountain side grid, and store the coordinates of the added points and edges to obtain a boundary line segment list;
[0061] Step 4: Construct the cross-section triangular grids of each formation, and then obtain the formation models of all formations;
[0062] Step 4.1: Based on the obtained boundary line segment list, use the bidirectional proximity search method to obtain a set of contour line polygons. The set of contour line polygons includes multiple polygon contour lines. The polygon contour line refers to the contour line obtained from a top-down perspective for each formation grid after the cutting is completed;
[0063] Generally, there is only one contour line polygon for the cutting surface. However, in actual situations, multiple, including islands, and complex contour polygons are the norm for the cutting surface.
[0064] Step 4.2: Determine the inclusion relationship between the polygon contour lines in the set of contour line polygons. According to the inclusion relationship between the polygon contour lines, take the polygon contour lines that are not included by other polygon contour lines as the outer rings. From the outer rings inward, obtain two adjacent polygon contour lines with an inclusion relationship, and form multiple target contour lines by combining the two adjacent polygon contour lines with an inclusion relationship, as well as independent contour lines that do not include other polygon contour lines and are not included by other polygon contour lines;
[0065] Among them, determining the inclusion relationship between the polygon contour lines in the set of contour line polygons specifically includes in the specific implementation process: if the current judgment ring includes the inner ring but is not included by other rings, it is the outer ring. Take out this ring and all the inner rings it includes. Generate a subsequence and further detect the inner rings of this subsequence. If the inner ring is not included by other inner rings, then this inner ring is an inner ring of the taken-out outer ring; if a certain inner ring is included by other inner rings, then this inner ring is the outer ring, and repeat the above steps to take out this ring and its included inner rings from the subsequence to generate a new subsequence and determine the inclusion relationship of each ring.
[0066] Step 4.3: For multiple target contour lines and independent contour lines, construct triangles for them to obtain the cross-section triangular meshes of each target contour line or independent contour line, and then obtain the cross-section triangular meshes of all target contour lines or independent contour lines. For each formation, the cross-section triangular meshes of all target contour lines or independent contour lines of the formation and the new mountain side meshes form the formation model of the formation, and then the formation models of all formations are obtained.
[0067] Among them, for multiple target contour lines and independent contour lines, constructing triangles for them to obtain the cross-section triangular meshes of each target contour line or independent contour line includes:
[0068] For each target contour line or independent contour line, on each target contour line or independent contour line, select three points and obtain the three-dimensional coordinates p 1 , p 2 , p 3 , calculate two edge vectors v 1 = p 2 - p 1 , v 2 = p 3 - p 2 , then calculate the cross product n = v 1 × v 2 . When the z-component of the cross product is greater than 0, the triangle is convex, and it is regarded as an "ear", and then construct a triangle based on these three points. When the z-component of the cross product is not greater than 0, re-select three points on each target contour line or independent contour line to obtain the cross-section triangular meshes of each target contour line or independent contour line.
[0069] The present invention uses higher-precision OSGB data to replace DEM to express the surface morphology. First, based on the OSG library, multi-level mining is carried out on the data of the study area and explicit triangular mesh information is exported. Then, topological correction is performed on this large-scale complex mesh, including non-connection between tiles and reconstruction of non-popular meshes within tiles using the Laplace smoothing method. For the stratigraphic layering information of the mountain, an implicit function expression method is adopted, and the HRBF implicit function is solved for the stratigraphic layering information extracted from the outcropping part of the mountain to construct an implicit three-dimensional geological interface function of the mountain strata. Then, the mountain is cut by the implicit surface cutting triangle algorithm, and through steps such as determining the inclusion relationship of contour lines and generating cross-sections by the ear-cutting method, the cut mesh is closed to obtain the final formation model. The present invention is simple to implement and has remarkable effects, meeting the requirements of practical engineering applications.
[0070] The present invention uses high-precision OSGB data to replace traditional DEM data for expressing the surface morphology, and through innovative methods and steps, realizes the fine stratigraphic modeling of complex landforms. By combining explicit and implicit modeling methods, especially through the topological correction of large-scale OSGB data, the application of implicit functions, and the optimization of cutting algorithms, the fineness and accuracy of the model are significantly improved. The actual application results show that the method of the present invention ensures the high precision of the exposed mountain body model on the surface and the ability to restore local details, demonstrates excellent effects, meets the high-precision requirements of actual projects, and further expands the applicability of the implicit modeling method in the field of geological research.
[0071] The above description is only a preferred embodiment of the present disclosure and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) disclosed in the embodiments of the present disclosure that have similar functions.
Claims
1. A method for fine stratigraphic modeling of surface exposed mountains based on OSGB data, characterized in that: include: Step 1: Obtain a target scene graph including exposed mountains on the surface, and triangulated network information of the exposed mountains on the surface in the target scene graph, wherein the triangulated network information includes three-dimensional coordinates of three vertices in the triangulated network; Step 2: Construct the initial mountain mesh based on the triangulated network information; Step 2.1: Load the triangulated network information of the exposed mountain on the surface of the target scene image, and determine the boundary line of the tile of the exposed mountain on the surface of the target scene image according to the triangulated network information, wherein there is a gap between two adjacent tiles; and divide the tiles in the target scene image according to the boundary line of the tile to obtain a plurality of tile data, wherein the tile data includes the three-dimensional coordinates of the three vertices of the triangulated network in the tile, the connection relationship of the three vertices of the triangulated network in the tile, and the three-dimensional coordinates of the vertices on the boundary line; Step 2.2: Adjust the boundaries of adjacent tiles so that all adjacent tiles are connected to obtain a first triangular mesh of the mountain exposed on the surface; Step 2.3: Correct the first triangular mesh to obtain the target triangular mesh; Step 2.4: According to the target triangular mesh, the boundary of the mountain exposed on the surface is determined in the target scene graph to obtain the first three-dimensional boundary contour line of the mountain exposed on the surface, the ordinate in the three-dimensional coordinates of each point on the first three-dimensional boundary contour line is adjusted to a preset height value to obtain the second three-dimensional boundary contour line, the points on the first three-dimensional boundary contour line are connected with the points on the second three-dimensional boundary contour line to construct triangles to obtain the side mesh of the mountain, and the target triangular mesh and the side mesh of the mountain constitute the initial mesh of the mountain; Step 3: Based on the stratigraphic information exposed on the surface of the mountain, the initial mountain grid is cut layer by layer from top to bottom through the HRBF implicit function surface to obtain multiple stratigraphic grids, and the stratigraphic grids are reconstructed to obtain a list of boundary line segments; Step 3.1: extracting stratigraphic information based on the exposed part of the surface mountain, wherein the stratigraphic information includes a stratigraphic boundary between two stratigraphic layers and stratigraphic attributes of each stratigraphic layer; Step 3.2: Take the points on the stratigraphic boundary line as implicit points, assign the vertical upward vector v(0,0,1) to the eigenvector of each point, and calculate the HRBF implicit function surface for each stratigraphic boundary line; Step 3.3: Arrange the HRBF implicit function surfaces of all stratum boundary lines in the order of strata from top to bottom. Based on the intersection algorithm between triangles and implicit surfaces, cut the initial mountain mesh through the HRBF implicit function surface to obtain multiple stratum meshes. At the same time, add the attributes of the stratum to the corresponding stratum meshes. For each stratum mesh, add points and edges on the boundary line after the stratum mesh is cut, construct triangles, obtain a new mountain side mesh, and store the coordinates of the added points and edges to obtain a list of boundary line segments. Step 4: Construct a cross-sectional triangular mesh of each stratum to obtain a stratigraphic model of all strata; Step 4.1: Based on the list of boundary line segments obtained by cutting, a contour polygon set is obtained by a bidirectional neighbor search method, wherein the contour polygon set includes a plurality of polygonal contour lines, and the polygonal contour line refers to a contour line obtained from a top-down perspective for each stratum grid after the cutting is completed; Step 4.2: Determine the inclusion relationship between the polygon contour lines in the contour polygon set. According to the inclusion relationship between the polygon contour lines, take the polygon contour lines that are not included by other polygon contour lines as the outer ring, and obtain two adjacent polygon contour lines that have an inclusion relationship from the outer ring inward. The two adjacent polygon contour lines that have an inclusion relationship are combined to obtain multiple target contour lines, as well as independent contour lines that do not contain other polygon contour lines and are not included by other polygon contour lines. Step 4.3: For multiple target contour lines and independent contour lines, triangles are constructed to obtain the cross-sectional triangular mesh of each target contour line or independent contour line, and then the cross-sectional triangular meshes of all target contour lines or independent contour lines are obtained. For each stratum, the cross-sectional triangular meshes of all target contour lines or independent contour lines of the stratum and the new mountain side mesh constitute the stratum model of the stratum, and then the stratum models of all strata are obtained.
2. The method for fine stratigraphic modeling of surface exposed mountains based on OSGB data according to claim 1 is characterized in that: Step 1 specifically includes: Obtain OSGB data of exposed mountains on the surface, wherein the OSGB data includes multiple scene graphs. In each scene graph, extract vertex data and obtain index information at the same time. The index information includes the connection relationship between vertices. According to the vertex data and the index information, construct a triangulated network for the exposed mountains on the surface in each scene graph. According to the needs, select a scene graph as the target scene graph in the scene graph after the triangulated network is constructed, and obtain the triangulated network information corresponding to the exposed mountains on the surface in the target scene graph.
3. The method for fine stratigraphic modeling of surface exposed mountains based on OSGB data according to claim 1 is characterized in that: Step 2.2 specifically includes: For two adjacent tiles, the distance between the vertices on the adjacent boundary lines of the two adjacent tiles is calculated according to the vertex coordinates on the adjacent boundary lines of the two adjacent tiles. When the distance between the vertices is less than a preset threshold, the vertex on one boundary line is moved to the position of the vertex on the other boundary line. The vertices on the adjacent boundary lines of all adjacent tiles are adjusted to obtain an initial triangular mesh. For unprocessed vertices on the boundary lines in the initial triangular mesh, new vertices are added to the edges of the triangles adjacent to the vertices, and triangles are constructed with the unprocessed vertices. The unprocessed vertices on the adjacent boundary lines of all adjacent tiles are adjusted to obtain a first triangular mesh.
4. The method for fine stratigraphic modeling of surface exposed mountains based on OSGB data according to claim 1 is characterized in that: Step 2.3 specifically includes: For each vertex in the first triangular mesh, the normal vector distribution of the vertex and the adjacent triangles is calculated to obtain the normal vector of the vertex, and the angle between the normal vectors of two adjacent vertices is calculated. If the angle between the normal vectors of two adjacent vertices is less than or equal to a preset threshold, no adjustment is required. If the angle between the normal vectors of two adjacent vertices is greater than the preset threshold, the triangular area where the two vertices are located is marked as a non-popular area. For all vertices in the non-popular area, the Laplace smoothing method is used to adjust the vertex coordinates. After correcting the coordinates of all vertices in the non-popular area, the target triangular mesh is obtained.
5. The method for fine stratigraphic modeling of surface exposed mountains based on OSGB data according to claim 4 is characterized in that: In step 2.3, for all vertices in the non-popular area, the Laplace smoothing method is used to adjust the vertex coordinates, which is achieved by the following formula: Among them, Adj i (P) represents the three-dimensional coordinates of vertex P in the non-popular area, U(p) represents the three-dimensional coordinates of vertex P after update, and n represents the number of vertices connected to vertex P in the non-popular area.
6. The method for fine stratigraphic modeling of surface exposed mountains based on OSGB data according to claim 1 is characterized in that: Step 3.2 is specifically implemented by the following formula: Among them, α i ∈R,β i ∈R 3 is the unknown coefficient of the implicit function; x j represents the jth implicit point, x i represents the ith implicit point; f(x j ) represents the function value of the jth implicit point brought into the implicit function; Represents the partial derivative of the j-th implicit point into the implicit function; is the radial basis function, where represents the distance from the jth implicit point to the ith implicit point; represents the partial derivative of the radial basis function, H is the Hess calculation factor; v j is the feature vector of the jth point; n is the number of implicit points.
7. The method for fine stratigraphic modeling of surface exposed mountains based on OSGB data according to claim 1 is characterized in that: In step 4.3, triangles are constructed for multiple target contours and independent contours to obtain a cross-sectional triangular mesh of each target contour or independent contour, including: For each target contour line or independent contour line, three points are selected on each target contour line or independent contour line, and the three-dimensional coordinates p1, p2, and p3 of the three points are obtained. Two edge vectors v1=p2-p1 and v2=p3-p2 are calculated, and then the cross product n=v1×v2 of the two edge vectors is calculated. When the z component of the cross product is greater than 0, a triangle is constructed based on these three points. When the z component of the cross product is not greater than 0, three points are selected again on each target contour line or independent contour line to obtain a cross-sectional triangular mesh of each target contour line or independent contour line.