A method for quickly cutting open-pit coal mine three-dimensional geological model

Abstract

This invention relates to a rapid trimming method for 3D geological models in open-pit coal mines, comprising: S1, constructing a bounding box BVH tree for a large-scale triangular mesh; S2, rapidly calculating the intersection lines of triangular faces based on the bounding box BVH tree; S3, classifying topological relationships and constructing an associated boundary cache table; S4, subdividing the surface of flat triangular faces embedded in the trimming boundary; and S5, classifying and selecting triangular faces on both sides of the trimming boundary. This invention addresses the dynamic editing needs of 3D grid data by starting with the processing of intersecting triangular face topological relationships and the trimming process. By ensuring topological consistency on a triangular face-by-triangular basis, it improves the overall robustness and effectiveness of the algorithm, achieving rapid, stable, and reliable trimming and updating of 3D geological models. It effectively solves problems such as high computational complexity, low processing efficiency, and the tendency to generate topological relationship errors such as non-manifold edges and singular nodes during the trimming operation, which disrupt model continuity and geometric consistency, thus affecting the reliability of subsequent computational analysis and secondary model editing.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a method for rapid cutting of a three-dimensional geological model of an open-pit coal mine. Background Technology

[0002] Dynamic editing of the three-dimensional geological model of an open-pit coal mine is a key foundation for the planning of stripping, mining, and drainage schedules, as well as the real-time updating of the three-dimensional geological model.

[0003] Currently, mining engineering software generally uses three-dimensional solids or triangular grids as the main way to express geological models. However, due to the influence of multiple factors such as the current status of mining and stripping projects and changes in complex geological structures, the three-dimensional geological models of open-pit mines often need to be dynamically adjusted and updated continuously with the production process.

[0004] Traditional Boolean operation methods based on solid models have significant shortcomings in terms of voxel checking conditions, computational complexity, and efficiency. Furthermore, editing based on grid models is prone to non-manifold topological errors, resulting in poor algorithm stability and often requiring extensive post-processing corrections before further computation or secondary editing can proceed, severely impacting model update efficiency and schedule planning efficiency. These problems are particularly acute given the widespread application of high-precision, large-scale data acquisition methods such as UAV surveying and laser scanning, where the rapid increase in data volume exacerbates these issues. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a rapid trimming method for three-dimensional geological models of open-pit coal mines. Addressing the dynamic editing requirements of three-dimensional grid data, this method starts with the processing and trimming of intersecting triangular facet topology relationships. By ensuring topological consistency on a triangular facet-by-triangular basis, the robustness and effectiveness of the algorithm are improved overall, thereby achieving rapid, stable, and reliable trimming and updating of the three-dimensional geological model.

[0006] The technical solution adopted in this invention is as follows:

[0007] The present invention proposes a method for rapid trimming of a three-dimensional geological model of an open-pit coal mine, which specifically includes the following steps: S1. Construct the bounding box BVH tree of a large-scale triangular network; S2. Fast calculation of triangular intersection lines based on bounding box BVH tree; S3. Topological relationship classification and construction of associated boundary cache table; S4, Flat triangular surface subdivision embedded in the clipping boundary; S5. Sorting and picking the triangular faces on both sides of the cutting boundary.

[0008] Furthermore, step S1 includes: during the construction of the bounding box BVH tree of large-scale triangular faces, extracting the coordinates of the three vertices of the triangular face, calculating the extreme values ​​of the coordinates in the three directions, and using the maximum and minimum values ​​to construct the AABB axis-aligned bounding box of the triangular face; determining the longest side among the three axes of the bounding box (x / y / z) as the axis of symmetry, establishing BVH nodes, storing bounding box information, index information, and node pointers in all nodes, calculating the center of the bounding box along the axis and sorting them, dividing the space into two parts according to the sorting result of the objects, and organizing them into left and right leaf nodes; repeating the above steps until all objects are stored in the leaf nodes; performing hierarchical compression on the organized tree structure, converting invalid parent nodes into sibling nodes to improve traversal efficiency.

[0009] Furthermore, step S2 includes: assigning a unique identifier (ID) to each bounding box by the BVH node and establishing a mapping record table between the bounding box and the ID; using the BVH tree to determine the intersection of the two triangular faces; maintaining a dictionary before processing, which records the intersection relationships of all triangular faces in the two triangular networks; using the ID of the clipped triangular face as the key and the value as a set of IDs of all triangular faces in the clipped triangular network that have an intersection relationship with the clipped triangular face; and performing pairwise traversal of the nodes in the two BVH trees starting from the BVH root node.

[0010] Furthermore, the traversal process uses the following logic for judgment: (1) Preliminary intersection relationship is used As a criterion; (2) If the bounding boxes of two nodes do not intersect, then perform the Reject operation on the node pair to terminate the traversal of this branch; (3) If the bounding boxes of two nodes intersect, then perform the Accept operation on the node pair, add the node pair to the candidate set, and proceed to a finer level for further judgment; Traverse the aforementioned dictionary, perform strict intersection calculations between the triangles corresponding to the keys and all triangles corresponding to the values, obtain all short line segments on the clipped triangles, and manage the intersection lines corresponding to the clipped triangles.

[0011] Furthermore, step S4 includes: using the clipped triangle nodes, edges, and short lines of intersection as the data source for modeling; using the open-source triangle algorithm to re-subdivide the planar triangles; and using the triangle optimization strategy in the algorithm library to obtain a new surface subdivision triangular mesh subdivided along the short lines. The clipped triangle face is divided into multiple parts along the intersection lines.

[0012] Furthermore, step S5 includes: searching for common edge triangles outward from the boundary along the clipping boundary segmented by the clipped triangles, until an open edge is encountered or the search stops when the boundary is reached. All the searched triangles are classified according to the left and right vectors of the clipping boundary. The classification results will eventually form multiple independent parts, constructing different types of models for actual business needs, and completing the fast clipping task.

[0013] Furthermore, when constructing a bounding box with AABB-aligned triangular faces, the triangular faces involved in constructing the bounding box must be non-zero area triangular faces, meaning that no two or three of the three nodes of the triangular face should overlap or be collinear.

[0014] Furthermore, the zero-area triangular face is a triangular face with an area of ​​less than 0.1. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a rapid cutting method for a three-dimensional geological model of an open-pit coal mine proposed in this invention. Figure 2 This is a schematic diagram illustrating three types of triangular surfaces divided by the line segment of the intersection line in this invention; Figure 3 This is a schematic diagram illustrating the working principle of the unordered straight line segment combination polyline in this invention, where d is the distance between two nodes; It is a constant, 0.001; Figure 4 This is a schematic diagram illustrating the principle of triangular surface subdivision in this invention; Figure 5 This is a schematic diagram of the triangular sorting type in this invention, where ag is a node of the intersection of polylines; Figure 6 This is a schematic diagram of the triangle classification and picking search process in this invention, where S is a set of boundaries that need to be further subdivided after classification; Figure 7 This is a schematic diagram of the sheared coal seam entity in an embodiment of the present invention; Figure 8 This is a schematic diagram illustrating the effect of cutting coal seams in the current state in an embodiment of the present invention.

[0016] In the attached diagram, the following labels are used: 1-straight line segment of the intersection line; 2-section of the intersection line; 3-triangular facet that has been cut off; 4-subdivision node added to the plane; 5-intersection line node; 6-three subdivision triangular facets obtained by re-dividing along the intersection line. Detailed Implementation

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] See appendix Figure 1 The present invention proposes a method for rapid trimming of a three-dimensional geological model of an open-pit coal mine, which specifically includes the following steps: S1. Constructing the Bounding Box BVH Tree of a Large-Scale Triangulated Mesh: During the construction of the Bounding Box BVH tree of a large-scale triangulated mesh, the coordinates of the three vertices of each triangle are extracted, and the extreme values ​​of the coordinates in the three directions are calculated. The maximum and minimum values ​​are used to construct the AABB-aligned bounding boxes of the triangles. The longest side among the x, y, and z axes of the bounding box is determined as the axis of symmetry. BVH nodes are established, and all nodes store bounding box information, index information, and node pointers. The center of the bounding box is calculated along the axis and sorted. The space is divided into two parts according to the sorting result, organized into left and right leaf nodes. This process is repeated until all objects are stored in leaf nodes. The organized tree structure is then subjected to hierarchical compression, converting invalid parent nodes into sibling nodes to improve traversal efficiency.

[0019] S2. Fast Calculation of Triangle Intersection Lines Based on Bounding Box BVH Tree: Each BVH node assigns a unique identifier (ID) to each bounding box and establishes a mapping record table between bounding boxes and IDs. The recorded unique IDs are used to identify the corresponding specific triangle object during BVH judgment, thus avoiding direct manipulation of the original geometric data and achieving efficient management and fast indexing. The intersection of two triangles is determined using the BVH tree. Before processing, a dictionary is maintained to record the intersection relationships of all triangles in the two triangular networks. The dictionary uses the ID of the clipped triangle as the key, and the values ​​are a set of IDs of all triangles in the clipped triangular network that have an intersection relationship with the clipped triangle. Starting from the BVH root node, the nodes in the two BVH trees are traversed in pairs. The traversal process uses the following logic for judgment: (1) Use of preliminary intersection criterion As a criterion; Where A and B are any two bounding boxes being compared. , This represents the maximum and minimum coordinates of bounding box A in the x-direction. Represents logical OR, Indicates logical NOT; (2) If the bounding boxes of two nodes do not intersect, then perform a Reject operation on the node pair and terminate the traversal of this branch; (3) If the bounding boxes of two nodes intersect, then perform the Accept operation on the node pair, add the node pair to the candidate set, and proceed to a finer level for further judgment.

[0020] Iterate through the aforementioned dictionary, performing strict intersection calculations between the triangle corresponding to the key and all triangles corresponding to the value, to obtain all short line segments on the clipped triangle. The types of all short lines are as follows: Figure 1 As shown, the intersection lines are managed in relation to the cut triangles.

[0021] S3. Topological Relationship Classification and Associative Boundary Cache Table Construction: Unordered line segments on the triangular face are spliced ​​into polyline intersections: After processing in step S2, the intersections are unordered intersecting line segments. The shape of these connected line segments is as follows... Figure 3 As shown, these disordered straight line segments come from the intersection results of continuous triangular networks, so they can be spliced ​​into multi-segment intersection lines by connecting the beginning and end.

[0022] S4. Subdivision of flat triangles embedded in the clipping boundary: All short lines of intersections lie on the clipped triangle, such as... Figure 4 As shown in (a), the clipping process requires dividing the triangular faces at the short straight line positions to form the triangular face boundaries. To achieve this, in this step, the clipping triangle nodes, edges, and intersection lines are all used as data sources for modeling. The open-source triangle algorithm is used to re-subdivide the planar triangles. By employing the triangle optimization strategy in the algorithm library, a new surface subdivision triangular mesh can be obtained by subdividing along the short straight lines. The result is as follows. Figure 4 As shown in (b), the cutting triangle can be divided into multiple parts along the intersection line.

[0023] S5. Triangles on both sides of the trimming boundary are sorted and selected: Along the trimming boundary divided by the trimmed triangles, the common edge triangles are searched outward from the boundary until an open edge is encountered or the search stops when the boundary is reached. All the searched triangles are classified according to the left and right vectors of the trimming boundary. The classification results will eventually form several independent parts, which can be used to construct different types of models for actual business needs such as quantity calculation and stripping engineering auxiliary design, and complete the fast trimming task.

[0024] The bounding box for constructing the triangular faces is an AABB axis-aligned bounding box. Furthermore, the triangular faces participating in the construction of the 3D bounding box must not have zero area; that is, no two or three points among the three nodes of a triangular face should overlap or be collinear. The term "zero area triangular face" is used because in actual models, some triangular faces do not have a truly zero area, but rather an area infinitely close to zero, which prevents the proper calculation of topological relationships. Therefore, a triangle with an area < 0.1 is considered geometrically meaningless and is not allowed to participate in topological relationship calculations. Such triangular faces are conventionally referred to as zero-area triangular faces in this invention.

[0025] To ensure stable and reliable topological relationship calculations, this invention makes specific stipulations regarding the data length, data type, and overlap criteria for 3D points. Since most 3D geological models for mines are currently standardized in the National Geodetic 2000 coordinate system, integer data lengths are generally 6-7 digits. Therefore, the algorithm design requires that all data points be converted from rendered single-precision data to double-precision floating-point numbers during topological relationship calculations to ensure that the data type length meets computational requirements. For determining whether two points overlap, a distance criterion of less than 0.001 between them is used; points meeting this criterion are defined as duplicate points.

[0026] To improve computational efficiency during the initial screening of intersecting triangular faces, the bounding box calculation during the traversal of the clipped faces needs to screen out all triangular faces that intersect with the clipped triangular mesh at once, and group them into two sets: intersecting and non-intersecting. The screening process does not directly perform triangular face intersection calculations, but only checks whether the projection intervals of the two AABB bounding boxes overlap in the x and y directions, i.e., there is no separating axis at the projection position. The criterion is as follows:

[0027] in For logical "OR", For logical NOT; When splicing discrete, disordered intersecting line segments into an intersection line, all the final intersection lines are represented by polylines. There may be one or more polylines at the split position. Depending on whether the cut triangular network is closed or not, the intersection line polyline can be a closed polyline or an open polyline. During the search process, the absolute distance error between nodes is less than 0.001 as the criterion. The search can be stopped as long as the starting point and ending point of the polyline do not meet the criterion requirement with nodes of non-adjacent line segments. After stopping, the search for the next polyline is carried out until all line segments have completed the search task. When dividing the triangular face into intersection lines, it is necessary to subdivide the triangular face into which the line segments of the intersection line are embedded. The boundary of the original triangular face and the embedded line segments need to be used as constraints to participate in the two-dimensional triangulation. The triangular face is subdivided according to the optimization strategy of the two-dimensional triangulation. Since it is a two-dimensional triangulation algorithm, the insertion point will be missing the coordinate z value. It is necessary to use the z value of the three nodes to linearly interpolate to obtain the three-dimensional coordinate information of the supplementary point. The classification and selection of triangular faces mainly includes two categories: triangular faces that intersect with the clipped triangular mesh and are then subdivided by the surface, and triangular faces that do not intersect. During selection, these two types of triangular faces are mixed together in set G. The traversal process during selection first traverses the clipping boundaries, finds the triangular faces on the left and right sides of each clipping boundary, and marks them as... , Two sets, placed on the left. Group, placed on the right side Group the triangles and find the triangles adjacent to its three sides. Continue this process until you encounter an open edge, a clipped boundary, or all triangles in G have been traversed. Then, group all the adjacent triangles according to their connectivity. , Two groups, the triangles found in G through adjacency search will be removed from G.

[0028] Addressing the issue that 3D geological models of open-pit coal mines are typically composed of large-scale, irregular triangular meshes, and that model trimming involves numerous spatial intersection judgments and topological relationship reconstructions between triangular faces, directly performing pairwise intersection calculations of the triangular mesh leads to high computational complexity and poor stability, failing to meet the dual requirements of efficiency and reliability in engineering applications. This invention systematically decomposes and optimizes the trimming process by introducing a multi-level spatial filtering and local geometric reconstruction mechanism. By introducing bounding box spatial decomposition and topological constraint trimming mechanisms at the triangular mesh level, the trimming problem of complex 3D geological models is transformed into a 2D geometric reconstruction and topological classification problem within a finite local region. Combined with a search algorithm, this enables rapid, on-demand model segmentation along the trimming line, thereby achieving efficient and stable trimming of large-scale triangular meshes while ensuring geometric consistency and topological correctness.

[0029] The present invention will be further illustrated below through specific embodiments and comparative examples: This embodiment presents a method for rapid trimming of a three-dimensional geological model of an open-pit coal mine. The specific implementation process of this method is as follows: S1. Construct a bounding box BVH tree for large-scale triangular faces: like Figure 2 As shown, each triangular facet in the 3D geological model is extracted, and the spatial coordinates of its three vertices are obtained. The extreme values ​​of the coordinates of the three vertices in the X, Y, and Z directions are calculated, and the minimum and maximum values ​​in the three coordinate axes are determined respectively. Based on this, the axis-aligned bounding box (AABB) of the triangular facet is constructed. BVH nodes are constructed, and the node bounding box information, the index information of the triangular facet corresponding to the node, and the pointers of the left and right nodes are stored. Using the AABB set as input, a hierarchical bounding box is constructed by recursively partitioning from the orientation downwards. The specific steps are as follows: S101: For the AABB set covered by the current node, calculate its overall bounding box as the bounding box of the current node; S102: Determine whether the number of triangles contained in the current node is less than a preset threshold. If so, set the current node as a leaf node and terminate the partitioning of the node. S103: If the current node still needs to be divided, then select the direction with the largest size as the dividing axis based on the size of the current node's bounding box in the X, Y, and Z directions; S104: Sort the AABBs according to the geometric center of each AABB along the dividing axis, and divide the AABB set into two subsets, left and right, using the median partitioning strategy, and generate left child nodes and right child nodes respectively. S105: Repeat S101 to S104 for the left and right child nodes until all leaf nodes meet the termination condition, thus completing the construction of the BVH bounding box hierarchy.

[0030] Following the steps described above, after the BVH tree is constructed, invalid nodes in the tree structure are optimized by hierarchical compression to improve the efficiency of subsequent traversals.

[0031] Step S2: Fast calculation of triangular intersection lines based on bounding box BVH tree: The BVH node assigns a unique identifier (ID) to each bounding box and establishes a mapping record table between bounding boxes and IDs. The unique IDs recorded are used to identify the corresponding specific triangular face objects during the BVH judgment process, thereby avoiding direct manipulation of the original geometric data and achieving efficient management and fast indexing.

[0032] The intersection of two triangles is determined using a BVH tree. Before processing, a dictionary is maintained to record the intersection relationships of all triangles in the two triangular networks. The dictionary uses the ID of the clipped triangle as the key and the value is a set of IDs of all triangles in the clipped triangular network that have an intersection relationship with the clipped triangle. Starting from the root node of BVH, perform pairwise traversals of nodes in the two BVH books, using the following logic for judgment during the traversal process: (1) Use of preliminary intersection criterion As a criterion; (2) If the bounding boxes of two nodes do not intersect, then perform a Reject operation on the node pair and terminate the traversal of this branch; (3) If the bounding boxes of two nodes intersect, then perform the Accept operation on the node pair, add the node pair to the candidate set, and proceed to a finer level for further judgment.

[0033] Traverse the aforementioned dictionary, perform strict intersection calculations between the triangles corresponding to the keys and all triangles corresponding to the values, obtain all short line segments on the clipped triangles, and manage the intersection lines corresponding to the clipped triangles.

[0034] Step S3: Piece together the disordered line segments on the triangular face into a polyline intersection line: After processing in step S2, the intersection lines are scattered, disordered straight line segments. The shape of these connected straight line segments is as follows: Figure 3 As shown, these disordered straight line segments come from the intersection results of continuous triangular networks, so they can be spliced ​​into multi-segment intersection lines by connecting the beginning and end.

[0035] Step S4: Subdividing the flat triangular facets embedded in the clipping boundary: All the shorter lines of the intersection lines lie on the cut triangle face, such as Figure 4 As shown in (a), the clipping process requires dividing the triangular faces at the short straight line positions to form the triangular face boundaries. To achieve this, in this step, the clipping triangle nodes, edges, and intersection lines are all used as data sources for modeling. The open-source triangle algorithm is used to re-subdivide the planar triangles. By employing the triangle optimization strategy in the algorithm library, a new surface subdivision triangular mesh can be obtained by subdividing along the short straight lines. The result is as follows. Figure 4 As shown in (b), the cutting triangle can be divided into multiple parts along the intersection line.

[0036] Step S5: Sorting and selecting the triangular faces on both sides of the trimming boundary: Because open-pit coal mines are layered deposits, the triangular meshes in the 3D geological model are constructed using a partitioning algorithm on the XY plane. Therefore, each triangular facet can be classified using the left and right directions of the vectors. For example... Figure 5 As shown in (a), and These are two adjacent triangles sharing side BC, with ab, bc, cd, and de as... The intersection of the short straight lines within the line, ef is Within the segment, first connect ab, bc, cd, de, and ef end-to-end according to step 3 to form a polyline, and then... Figure 5 (a) unifies the direction of the straight segments in the polyline, and the polyline and the boundary of the triangular face form two regions, left and right. The triangular faces in different regions will be classified into different regions.

[0037] Besides the need to classify the subdivided triangular faces, such as... Figure 5 As shown in (b), with , The adjacent triangles also include other triangles that did not participate in the subdivision, such as... , , , , Wait, these triangles also need to be separated along the intersection boundary; For the grouping and classification requirements of adjacent triangular faces, Figure 6Using a small number of triangles as an example, this demonstrates a recursive search strategy. The process involves traversing the S-boundary obtained in the preceding steps, acquiring each straight segment of the polyline boundary, identifying boundaries excluding those not belonging to intersection lines such as AB, BD, and Dg, and searching for adjacent triangular faces along the direction of the arrows in the adjacent graph. If an open edge or a directional intersection line is encountered during the search, the search in that direction is stopped. This ensures that all triangles and all adjacent edges are searched, thus completing the entire search process. This allows for the sorting of triangular faces along the trimming boundary. The resulting groups of triangular faces are then reconstructed into meshes, completing the trimming task.

[0038] like Figure 7 As shown in Tables 1 and 2, the present invention is compared with traditional methods in terms of computational accuracy and reliability in handling topological relationships. The results in the tables show that the computational accuracy of the present invention is less than 2% of the volume calculation error compared to traditional methods, but it has better computational time efficiency and the ability to handle non-traditional topological relationships, resulting in better reliability.

[0039] Table 1 Comparison of Quantity Calculation Accuracy

[0040] Table 2 Computational efficiency and control of non-prevailing topology relationships

[0041] Based on the above steps, this embodiment takes the clipping between a 3D geological model and an existing surface model of an open-pit coal mine as an example. The clipping result is as follows: Figure 8 As shown, the surface was subdivided at the intersection of the shear plane and the coal seam, i.e., the area selected by the dashed box in the figure, and its topological relationship was optimized to ensure that the model can be further calculated for secondary topological relationships.

[0042] All matters not covered in this invention are common knowledge.

[0043] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for rapid cutting of a three-dimensional geological model of an open-pit coal mine, characterized in that, The method includes the following steps: S1. Construct the bounding box BVH tree of a large-scale triangular network; S2. Fast calculation of triangular intersection lines based on bounding box BVH tree; S3. Topological relationship classification and construction of associated boundary cache table; S4, Flat triangular facet surface subdivision embedded in the clipping boundary; S5. Sorting and picking the triangular faces on both sides of the cutting boundary.

2. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 1, characterized in that: Step S1 includes: during the construction of a large-scale triangular bounding box (BVH) tree, extracting the coordinates of the three vertices of the triangular face, calculating the extreme values ​​of the coordinates in the three directions, and using the maximum and minimum values ​​to construct an AABB-aligned bounding box for the triangular face; determining the longest side among the x / y / z axes of the bounding box as the axis of symmetry, establishing BVH nodes, storing bounding box information, index information, and node pointers in all nodes, calculating the center of the bounding box along the axis and sorting them, dividing the space into two parts according to the sorting result of the objects, and organizing them into left and right leaf nodes; repeating the above steps until all objects are stored in leaf nodes; performing hierarchical compression on the organized tree structure, converting invalid parent nodes into sibling nodes to improve traversal efficiency.

3. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 2, characterized in that: Step S2 includes: assigning a unique identifier (ID) to each bounding box by the BVH node and establishing a mapping record table between the bounding box and the ID; using the BVH tree to determine the intersection of the two triangular faces; maintaining a dictionary before processing, which records the intersection relationships of all triangular faces in the two triangular networks; using the ID of the clipped triangular face as the key and the value as a set of IDs of all triangular faces in the clipped triangular network that have an intersection relationship with the clipped triangular face; and performing a pairwise traversal of the nodes in the two BVH trees starting from the BVH root node.

4. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 3, characterized in that: The traversal process uses the following logic for judgment: (1) Preliminary intersection relationship is used As a criterion; (2) If the bounding boxes of two nodes do not intersect, then perform the Reject operation on the node pair to terminate the traversal of this branch; (3) If the bounding boxes of two nodes intersect, then perform the Accept operation on the node pair, add the node pair to the candidate set, and proceed to a finer level for further judgment; Traverse the aforementioned dictionary, perform strict intersection calculations between the triangles corresponding to the keys and all triangles corresponding to the values, obtain all short line segments on the clipped triangles, and manage the intersection lines corresponding to the clipped triangles.

5. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 4, characterized in that: Step S4 includes: using the clipped triangle nodes, edges, and short lines of intersection as the data source for modeling; using the open-source triangle algorithm to re-subdivide the planar triangles; and using the triangle optimization strategy in the algorithm library to obtain a new surface subdivision triangular mesh subdivided along the short lines. The clipped triangle face is divided into multiple parts along the intersection lines.

6. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 5, characterized in that: Step S5 includes: searching for common edge triangles outward from the boundary along the clipping boundary segmented by the clipped triangles until an open edge is encountered or the search stops when the boundary is reached. All the searched triangles are classified according to the left and right vectors of the clipping boundary. The classification results will eventually form multiple independent parts, constructing different types of models for actual business needs, and completing the fast clipping task.

7. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 2, characterized in that: When constructing an AABB-aligned bounding box for triangular faces, the triangular faces involved in constructing the bounding box must be non-zero area triangular faces, meaning that no two or three of the three nodes of a triangular face should overlap or be collinear.

8. The method for rapid cutting of a three-dimensional geological model of an open-pit coal mine according to claim 7, characterized in that: The zero-area triangle is a triangle with an area of ​​less than 0.1.

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