BIM model three-dimensional projection plane extraction method, electronic equipment and medium

Abstract

The invention provides a BIM model three-dimensional projection plane extraction method, electronic equipment and a medium, and the method comprises the steps: carrying out the triangularization processing of a BIM model, and obtaining a triangularization mesh model; calculating the projection area and the normal direction of the triangle in the P direction, and deleting the triangle of which the vertex is repeated and the projection area is 0 or the normal direction is opposite to the P direction; calculating a value range of coordinate values of all vertexes of the remaining triangles in the P direction, and dividing the value range into a plurality of intervals; classifying the remaining triangles into a plurality of intervals to obtain a plurality of triangle sets; for each triangle set, extracting a two-dimensional vector surface; and sorting the two-dimensional vector surfaces according to a sequence from small projection height to large projection height, and extracting to obtain a three-dimensional vector surface. According to the method, projection plane extraction is performed after triangularization based on the BIM model, the influence of a professional design software production environment and a multi-source heterogeneous storage format is eliminated, and universality is achieved; compared with two-dimensional expression, the method for extracting the three-dimensional projection surface result provides finer geometric range description, and calculation is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological models, and in particular relates to a method for extracting a three-dimensional projection surface of a BIM model, electronic equipment and a medium. Background Art

[0002] The data sources of the City Information Model (CIM) include BIM, GIS (Geographic Information System) and IoT (Internet of Things Implementation Perception Data) models, which are characterized by multi-source heterogeneity. Among them, the BIM model (Building Information Modeling) is a building information model, which is generally expressed by component modeling and entity modeling. It can be parametrically designed or modified, has a complete internal structure and external form, and contains complex design information such as geometry, physics, materials, attributes, and rules. When the BIM model is integrated with other CIM data sources in the same scene, there will be problems such as different production time, accuracy, scope, and method, resulting in different model expression results. For example, there are overlaps and occlusions between the structures expressed by the BIM model and the oblique photography or terrain models obtained by the actual surface information modeling. Therefore, the model must be integrated to ensure the rationality, accuracy, and consistency of the model expression.

[0003] Since BIM models have higher accuracy in expressing information, the currently commonly used fusion technology solution is to remove other CIM models within the geometric expression range of the BIM model through the clipping method, and then perform the fusion expression and display of multi-source heterogeneous data. However, currently, manual drawing or extraction from other data sources (drawings, etc.) is widely used to obtain the two-dimensional geometric expression range of the BIM model (generally a vector surface on the XY plane) to clip other CIM models. Since the expression range lacks elevation information (Z axis), all geometric points in the entire range are stretched to the same elevation surface after clipping, which is seriously inconsistent with the elevation expression of the BIM model. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies in the prior art and provide a method, electronic device and medium for extracting a three-dimensional projection surface of a BIM model, which can extract the three-dimensional projection surface of the BIM model with simple calculation.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for extracting a three-dimensional projection surface of a BIM model comprises the following steps:

[0007] S1: triangulate the BIM model to obtain a triangulated mesh model;

[0008] S2: traverse all triangles in the triangulated mesh model, delete other triangles with the same vertex coordinates as any triangle; calculate the projection area and normal of the remaining triangles in the P direction, and delete the triangles with a projection area of ​​0 or a normal opposite to the P direction;

[0009] S3: Calculate the coordinate range of all vertices of the remaining triangles processed by S2 in the P direction d = [d min ,d max ], divide d into n intervals; where d min is the minimum coordinate value of all vertices of the remaining triangles after S2 processing in the P direction, d max is the maximum value of the coordinates of all vertices of the remaining triangles after processing by S2 in the P direction;

[0010] S4: According to the coordinate values ​​of all vertices of the remaining triangles after processing by S2 in the P direction, the remaining triangles after processing by S2 are classified into n intervals to obtain n triangle sets; if a triangle belongs to two or more triangle sets at the same time, the maximum value and the minimum value of the corresponding interval of each triangle set containing the triangle are taken to construct planes perpendicular to the P direction respectively, and the triangle is subdivided, and the subdivided triangle is reclassified into the triangle set of the corresponding interval;

[0011] S5: For the i-th triangle set S3 i , with its corresponding interval d i The minimum value of the projection height h i , constructed at the projection height h i And the plane perpendicular to direction P is the projection plane M i , the triangle set S3 i All triangles in are projected onto the projection plane M i , we get the two-dimensional plane set S2 i ; Among them, 1≤i≤n;

[0012] S6: The two-dimensional plane set S2 i The triangles in are merged to obtain the projection height h i A two-dimensional vector surface;

[0013] S7: Repeat steps S5-S6 for all triangle sets to obtain n two-dimensional vector faces;

[0014] S8: Sort the two-dimensional vector surfaces in ascending order of projection height, and extract the three-dimensional vector surfaces.

[0015] The present invention extracts projection surfaces based on the triangulation of the BIM model, eliminates the influence of the professional design software production environment and multi-source heterogeneous storage formats, and has universal applicability; compared with the two-dimensional expression, the method for extracting the three-dimensional projection surface result provides a more detailed geometric range description, and the expression is relatively simple, and will not excessively increase the amount of clipping processing calculations or the volume of clipping result expression.

[0016] Furthermore, the P direction includes the X-axis, the Y-axis, and the Z-axis of the spatial rectangular coordinate system.

[0017] Further, Among them, d s Divide the interval into intervals.

[0018] Further,

[0019]

[0020] Furthermore, in S8, starting from the two-dimensional vector surface corresponding to the minimum projection height, geometric difference operations are performed with all two-dimensional vector surfaces less than its projection height in turn to obtain a three-dimensional vector surface. This ensures that when the projection height is not considered, the two-dimensional vector surfaces extracted from any two triangle sets do not intersect, thereby improving the accuracy of the three-dimensional vector surface.

[0021] Based on the same inventive concept, the present invention also provides an electronic device, including:

[0022] one or more processors;

[0023] A memory having one or more programs stored thereon, which, when executed by the one or more processors, enables the one or more processors to implement the steps of a method for extracting a three-dimensional projection surface of a BIM model.

[0024] Based on the same inventive concept, the present invention also provides a computer-readable storage medium storing a computer program, which implements the steps of the BIM model three-dimensional projection surface extraction method when executed by a processor.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention extracts projection surfaces based on the triangulation of the BIM model, eliminates the influence of the professional design software production environment and multi-source heterogeneous storage formats, and has universal applicability; compared with the two-dimensional expression, the method for extracting the three-dimensional projection surface result provides a more detailed geometric range description, and the expression is relatively simple, and will not excessively increase the amount of clipping processing calculations or the volume of clipping result expression. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The Mesh data structure of the present invention;

[0028] Figure 2 It is a flow chart of the method for extracting three-dimensional projection surface of a BIM model of the present invention;

[0029] Figure 3 Schematic diagram of the original triangulated BIM model of an embodiment of the present invention;

[0030] Figure 4 It is a schematic diagram of the three-dimensional projection surface extraction result of an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0032] Example

[0033] like Figure 2 The BIM model three-dimensional projection surface extraction method of this embodiment includes the following process:

[0034] 1. Triangulate the BIM model to obtain a triangulated mesh model; the BIM model can be exported as a triangulated mesh model with consistent geometric information expression through the built-in tools of the 3D design software. Use the Bentley platform MicroStationConnect Edition Update 16 software to export a project DGN design model into OBJ format, such as Figure 3 . It is further parsed into a unified custom Mesh data structure, such as Figure 1 .

[0035] A triangulated mesh model refers to a polygonal mesh composed entirely of triangles. Mesh is a data structure used in computer graphics to model various irregular objects. In the facets of a polygonal mesh, a triangle facet is the smallest unit to be divided, and its representation is relatively simple, flexible, and convenient for topological description. Mesh often refers to a triangle facet. The components represented by Mesh include vertices, edges, and faces.

[0036] 2. In the spatial rectangular coordinate system, any vertex V(x, y, z) of the triangulated mesh model is projected along the coordinate axis to become V ′ , when the projection direction is the X-axis direction, V ′ The coordinate value is (y, z); when the projection direction is the Y axis direction, V ′ The coordinate value is (x, z); when the projection direction is the Z axis, V ′ The coordinate value is (x,y).

[0037] Traverse all triangles in the triangulated mesh model and delete other triangles with the same vertex coordinates as any triangle; take the Z-axis direction of the spatial rectangular coordinate system as the projection direction, calculate the projection area and normal of the remaining triangles in the Z-axis direction, and delete the triangles with a projection area of ​​0 or a normal opposite to the Z-axis direction.

[0038] 3. Take the Z axis direction of the spatial rectangular coordinate system as the projection direction and calculate the coordinate value range of all vertices of the remaining triangle in the Z axis direction d = [d min ,d max ], divide d into n intervals, Among them, d s The interval division interval, d min is the minimum coordinate value of all vertices of the remaining triangles in the P direction, d max It is the maximum value of the coordinates of all vertices of the remaining triangles in the P direction.

[0039] In this embodiment, the minimum coordinate value is 265.487732 meters, and the maximum coordinate value is 344.25 meters; the interval division spacing is set to 10 meters.

[0040] 4. Traverse all remaining triangles and divide them into 8 triangle sets according to their Z-axis coordinate value range. If a triangle belongs to two or more triangle sets at the same time, take the maximum and minimum values ​​of the interval range corresponding to each triangle set containing the triangle to construct planes perpendicular to the Z-axis direction, split the triangle, and return the split triangle to the triangle set of the corresponding interval.

[0041] 5. For the i-th triangle set S3 i , with its corresponding interval d i The minimum value of the projection height h i , constructed at the projection height h i The plane perpendicular to the Z axis is the projection plane M i , the triangle set S3 i All triangles in are projected onto the projection plane M i , we get the two-dimensional plane set S2 i ; Among them, 1≤i≤8.

[0042] 6. Take the two-dimensional plane set S2 i Any triangle in is the starting two-dimensional polygon P, and traverses the two-dimensional plane set S2 iGet other triangles in turn and perform geometric union operations with the two-dimensional polygon P (using the GDAL library, version number 3.9.1, Union function in the OSGeo.OGR namespace). The result of each union operation continues to be stored in P and participates in the geometric union operation with the next triangle until the two-dimensional plane set S2 is obtained. i After all the triangle unions in are calculated, the two-dimensional plane set S2 i The fusion calculation result of the triangle is P, that is, when the projection height is h i A two-dimensional vector surface.

[0043] Geometric union operation: The set consisting of all elements belonging to set C or set D is called the union of C and D.

[0044] 7. Repeat steps 5 and 6 for all triangle sets to obtain 8 two-dimensional vector faces.

[0045] 8. Sort the two-dimensional vector surfaces with projected elevation extracted from each triangle set in order of projection height from small to large. Starting from the two-dimensional vector surface A corresponding to the minimum projection height, perform geometric difference operations with all two-dimensional vector surfaces B with a height less than its projection height (using the GDAL library, version number 3.9.1, Difference function under the OSGeo.OGR namespace). The result is the part of A outside the external boundary of B. It is ensured that when the projection elevation is not considered, the two-dimensional vector surfaces extracted from any two triangle sets do not intersect. The fusion result is a three-dimensional vector surface, that is, a two-dimensional vector surface with elevation information, such as Figure 4 .

[0046] Geometric difference operation: Let A and B be two sets, a set consisting of all elements that belong to A and not to B.

[0047] 9. Save the result output as a shp format file.

[0048] This embodiment extracts projection surfaces based on triangulation of the BIM model, eliminating the influence of professional design software production environment and multi-source heterogeneous storage formats, and has universal applicability. Compared with two-dimensional expression, this method provides a more detailed geometric range description for extracting three-dimensional projection surface results, and the expression is relatively simple, without excessively increasing the amount of clipping processing calculations or the volume of clipping result expression.

[0049] Another embodiment of the present invention provides an electronic device, including:

[0050] one or more processors;

[0051] A memory having one or more programs stored thereon, which, when executed by one or more processors, enables the one or more processors to implement the steps of the method for extracting the three-dimensional projection surface of a BIM model.

[0052] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory.

[0053] In some other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited herein.

[0054] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program, which implements the steps of a method for extracting a three-dimensional projection surface of a BIM model when the computer program is executed by a processor.

[0055] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A method for extracting a three-dimensional projection surface of a BIM model, characterized in that: The following steps are involved: S1: triangulate the BIM model to obtain a triangulated mesh model; S2: traverse all triangles in the triangulated mesh model and delete other triangles that have the same vertex coordinates as any triangle; Calculate the projection area and normal of the remaining triangles in the P direction, and delete the triangles whose projection area is 0 or whose normal is opposite to the P direction; S3: Calculate the coordinate range of all vertices of the remaining triangles processed by S2 in the P direction d = [d min ,d max ], divide d into n intervals; S4: According to the coordinate values ​​of all vertices of the remaining triangles after processing by S2 in the P direction, the remaining triangles after processing by S2 are classified into n intervals to obtain n triangle sets; if a triangle belongs to two or more triangle sets at the same time, the maximum value and the minimum value of the corresponding interval of each triangle set containing the triangle are taken to construct planes perpendicular to the P direction respectively, and the triangle is subdivided, and the subdivided triangle is reclassified into the triangle set of the corresponding interval; S5: For the i-th triangle set S3 i , with its corresponding interval d i The minimum value of the projection height h i , constructed at the projection height h i And the plane perpendicular to direction P is the projection plane M i , the triangle set S3 i All triangles in are projected onto the projection plane M i , we get the two-dimensional plane set S2 i ; S6: The two-dimensional plane set S2 i The triangles in are merged to obtain the projection height h i A two-dimensional vector surface; S7: Repeat steps S5-S6 for all triangle sets to obtain n two-dimensional vector faces; S8: sorting the two-dimensional vector surfaces in ascending order of projection height, and extracting the three-dimensional vector surfaces; Among them, d min is the minimum coordinate value of all vertices of the remaining triangles after S2 processing in the P direction, d max It is the maximum value of the coordinate values ​​of all vertices of the remaining triangles after processing by S2 in the P direction; 1≤i≤n.

2. The method for extracting a three-dimensional projection surface of a BIM model according to claim 1, characterized in that: The P direction includes the X-axis, Y-axis, and Z-axis of the spatial rectangular coordinate system.

3. The method for extracting a three-dimensional projection surface of a BIM model according to claim 1, characterized in that: Among them, d s Divide the interval into intervals.

4. The method for extracting a three-dimensional projection surface of a BIM model according to claim 3, characterized in that:

5. The method for extracting a three-dimensional projection surface of a BIM model according to claim 1, characterized in that: In S8, starting from the two-dimensional vector surface corresponding to the minimum projection height, geometric difference operations are performed with all two-dimensional vector surfaces smaller than its projection height in turn to obtain a three-dimensional vector surface.

6. An electronic device, characterized in that: include: one or more processors; A memory having one or more programs stored thereon, which, when the one or more programs are executed by the one or more processors, enables the one or more processors to implement the steps of the method according to any one of claims 1 to 5.

7. A computer-readable storage medium, characterized in that: The computer program is stored therein, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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