High-depletion geologic body three-dimensional modeling method based on subdivision curved surface

Abstract

The invention discloses a three-dimensional modeling method for a high-depletion geologic body based on a subdivided curved surface. The method comprises the following steps: S1, establishing a three-dimensional drilling model of each stratum according to geological drilling data; s2, taking the three-dimensional drilling model as a reference, and performing preliminary fitting on spatial distribution of a target geologic body by using a zero-defect closed hexahedral mesh model; s3, performing grid topology reconstruction operation and geometric fitting operation of point-line-plane adjustment on the hexahedral grid model to obtain a closed high-deficit control grid model; s4, converting the high-depletion control grid model into a closed high-depletion geologic body NURBS curved surface model; and S5, realizing fusion of the NURBS curved surface model of the high-depletion geologic body and the conventional stratum model in combination with Boolean operation. According to the method, preliminary modeling is carried out on the deficit characteristics through grid topology reconstruction, then a closed high deficit control grid model is converted into a closed high deficit geologic body NURBS curved surface model, and global or local real-time updating of the high deficit geologic body model is achieved.

Description

Technical Field

[0001] The invention relates to the field of three-dimensional geological modeling, and in particular to a three-dimensional modeling method of a high-genus geological body based on subdivision surfaces. Background Art

[0002] High-genus geological bodies are geological structures with multiple internal "hollowing" caused by intrusion and erosion, such as cover layers, lenses, fracture zones, pinch-out interlayers, intrusion and erosion, etc. Realizing fast and accurate modeling of high-genus geological bodies can greatly improve the efficiency of engineering geological survey and design, and provide an important geological model calculation basis for research related to structural stability and seepage safety. However, high-genus geological bodies have complex geometric shapes and genus characteristics, which are specifically manifested in the multi-value characteristics of the strata in the modeling area that appear repeatedly and alternately along the vertical direction and the data missing characteristics caused by local hollowing. When using conventional spatial coordinate weighted single-value interpolation methods (such as inverse distance weighting, natural neighbor interpolation, improved Shepard interpolation, Kriging, etc.) and explicit surface methods (such as non-uniform rational B-splines, polynomial interpolation, minimum curvature interpolation, etc.) to model high-genus geological bodies, there is a problem of data sampling conflict in the genus feature area, which makes the genus characteristics unable to be directly modeled, and requires a large number of interactive clipping and combination operations on the geological body model to express it, which is highly subjective, complex in modeling process, and low in modeling efficiency. Although the implicit surface modeling method can express high-genus characteristics quickly, conveniently and automatically, it is more suitable for modeling a single geological body such as a certain type of ore body. When it comes to multi-stratum modeling tasks, there will be problems such as overlapping stratum boundaries and inconsistent boundaries of local voids. In addition, since the implicit function control parameters are difficult to obtain directly, it is difficult to adjust and update the local geological body. Summary of the invention

[0003] The present invention aims to solve the deficiencies of the prior art and provides a three-dimensional modeling method for high-genus geological bodies based on subdivision surfaces. The genus features are preliminarily modeled through mesh topology reconstruction, and the closed high-genus control mesh model is converted into a closed high-genus geological body NURBS surface model based on the subdivision surface method.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A high-genus geological body three-dimensional modeling method based on subdivision surfaces comprises the following steps:

[0006] S1. Establish a three-dimensional drilling model of each stratum based on geological drilling data;

[0007] S2. Using the three-dimensional borehole model as a reference and combining the knowledge of geological experts, a zero-genus closed hexahedral grid model is used to preliminarily fit the spatial distribution of the target geological body;

[0008] S3, performing mesh topology reconstruction operations such as extrusion, lofting, subdivision, and bridging and geometric fitting operations such as point, line, and surface adjustment on the hexahedral mesh model to express the genus characteristics and obtain a closed high-genus control mesh model;

[0009] S4, based on the Catmull-Clark subdivision mode, the high-genus control grid model is converted into a closed high-genus geological body NURBS surface model;

[0010] S5. Combine Boolean operations to achieve the fusion of the high-genus geological body NURBS surface model and the conventional formation model.

[0011] When the topological structure and geometric shape of the high-genus control grid model are adjusted in the step S3, the corresponding high-genus geological body NURBS surface model is updated in real time;

[0012] After the high-genus geological body NURBS surface model and the conventional formation model are merged through Boolean operation in the S5 step, each geological body model is still a closed surface model, and can provide a numerical simulation calculation model for structural stability calculation and seepage analysis research through calculation grid division operation.

[0013] The beneficial effects of the present invention are as follows: the present invention performs preliminary modeling of genus characteristics through mesh topology reconstruction, and then converts a closed high-genus control mesh model into a closed high-genus geological body NURBS surface model based on a subdivision surface method, and can achieve global or local real-time updating of the high-genus geological body model by adjusting the topological structure and geometric shape of the control mesh model. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a flow chart of the present invention;

[0015] Figure 2 The subdivision surface is based on the standard bicubic B-spline surface control grid of the present invention;

[0016] Figure 3 An automatic update diagram of the high-genus geological body model of the present invention;

[0017] Figure 4 It is a fusion diagram of the high-genus geological body model of the present invention and the conventional formation model;

[0018] The following is a detailed description of the embodiments of the invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0020] A high-genus geological body three-dimensional modeling method based on subdivision surfaces, characterized in that it comprises the following steps:

[0021] S1. Establish a three-dimensional drilling model of each stratum based on geological drilling data;

[0022] S2. Using the three-dimensional borehole model as a reference and combining the knowledge of geological experts, a zero-genus closed hexahedral grid model is used to preliminarily fit the spatial distribution of the target geological body;

[0023] S3, then the hexahedral mesh model is subjected to mesh topology reconstruction operations such as extrusion, lofting, subdivision, and bridging, as well as geometric fitting operations such as point, line, and surface adjustment, to express the genus characteristics and obtain a closed high-genus control mesh model, such as Figure 1 (a~c).

[0024] S4, based on the subdivision surface, the high genus control grid model is converted into a closed high genus geological body NURBS surface model. The subdivision surface is based on a given grid M0, and a certain grid topology splitting rule and vertex geometric average rule are used to refine it in turn to obtain a grid sequence {M k , k=0,1,2…}, and the corresponding smooth surface can be obtained by continuous refinement. Common subdivision modes include Catmull-Clark subdivision mode (quadrilateral mesh), Doo-Sabin subdivision mode (quadrilateral mesh), and Loop subdivision mode (triangular mesh). Among them, the Catmull-Clark subdivision mode is a generalization of NURBS with a parameter interval of rectangular mesh topology to any topological structure, and is currently the most widely used.

[0025] The specific process of Catmull-Clark segmentation is as follows:

[0026] For Figure 2 The control mesh of the standard bicubic B-spline surface (i.e., NURBS surface) is denoted by p. ij , q represents the newly generated point, and we can get q 11 ,q 12 and q 22 , as shown in formulas (1) to (3):

[0027]

[0028]

[0029]

[0030] Where H = (q 11 +q 13 +q 31 +q 33 ) / 4, R=[(p 22 +p 12 ) / 2+(p22 +p 21 ) / 2+(p 22 +p 32 ) / 2+(p 22 +p 23 ) / 2] / 4

[0031] Then, equations (1) to (3) are expressed as a set of geometric rules, which can be generalized to any topology. These rules depend on the number of points around the face and the number of edges associated with the vertex, specifically:

[0032] 1) New face point - the average value of all original vertices on this face.

[0033] 2) New edge point - the average of the two new face points sharing the edge and the average of the midpoint of the old edge.

[0034] 3) New vertex point - H / n+2R / n+J(n-3) / n, where H is the average value of the new face points of all faces adjacent to the old vertex, R is the average value of the midpoints of all old edges related to the old vertex, and J is the old vertex.

[0035] After calculating these new points according to the geometric rules 1) to 3), set the following topological rules: connect each new face point with the new edge point defined on the old face, connect each new vertex point with the new edge points on all old edges on the old vertex point, and obtain all new edges. The face surrounded by the new edge is the new face and can be converted into a NURBS surface. Figure 1 (d).

[0036] When the model needs to be partially updated, the automatic update of the NURBS model of high-genus geological bodies can be achieved by adjusting the topological structure and geometric shape of the control grid, such as Figure 3 At the same time, since the final modeling result of the present invention is a closed NURBS surface model, it can be integrated with the conventional formation model, such as Figure 4 , and then through computational grid division operations, it can provide a basic model for numerical simulation calculations for structural stability calculations, seepage analysis and other studies.

[0037] In the description of the invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] In the invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be fixedly connected, detachably connected, or integrated; it can be mechanically connected, electrically connected, or able to communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0040] The invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the invention, or they are directly applied to other occasions without improvement, they are all within the scope of protection of the invention.

Claims

1. A high-genus geological body three-dimensional modeling method based on subdivision surfaces, characterized in that: The following steps are involved: S1. Establish a three-dimensional drilling model of each stratum based on geological drilling data; S2. Using the three-dimensional borehole model as a reference and combining the knowledge of geological experts, a zero-genus closed hexahedral grid model is used to preliminarily fit the spatial distribution of the target geological body; S3, performing mesh topology reconstruction operations such as extrusion, lofting, subdivision, and bridging and geometric fitting operations such as point, line, and surface adjustment on the hexahedral mesh model to express the genus characteristics and obtain a closed high-genus control mesh model; S4, based on the Catmull-Clark subdivision mode, the high-genus control grid model is converted into a closed high-genus geological body NURBS surface model; S5. Combine Boolean operations to achieve the fusion of the high-genus geological body NURBS surface model and the conventional formation model.

2. The high-genus geological body three-dimensional modeling method based on subdivision surface according to claim 1, characterized in that: When the topological structure and geometric shape of the high-genus control grid model are adjusted in the step S3, the corresponding high-genus geological body NURBS surface model is updated in real time.

3. The high-genus geological body three-dimensional modeling method based on subdivision surface according to claim 2 is characterized in that: After the high-genus geological body NURBS surface model and the conventional formation model are merged through Boolean operation in the S5 step, each geological body model is still a closed surface model, and can provide a numerical simulation calculation model for structural stability calculation and seepage analysis research through calculation grid division operation.

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