A three-dimensional crown model optimization method based on geometric information

Abstract

The present invention discloses a three-dimensional crown model optimization method based on geometric information, which relates to the field of computer-aided design, and specifically a three-dimensional crown model optimization method based on geometric information, comprising the following steps: S1, inputting an original crown model; S2, detecting and repairing non-manifold vertices; S3, obtaining the magnitude and direction of the vertex principal curvature using a quadratic surface fitting method; S4, filtering vertices based on the maximum curvature of the vertex and the distance to the edge; S5, deleting isolated connected domains of the model; S6, smoothing the model edges; and S7, optimizing the crown mesh model after smoothing the edges using an isotropic regridding method to obtain a final result. The present invention combines the geometric features of the crown model, can effectively remove redundant model areas caused by regional division errors, and simultaneously optimizes the topological structure of the input model and the size of the model data, which is beneficial to subsequent processing of the CAD software and improves the efficiency of data interaction between the front-end and back-end of the software.

Description

Technical Field

[0001] The present invention relates to the field of computer-aided design, and in particular to a three-dimensional crown model optimization method based on geometric information. Background Art

[0002] With the rapid adoption of digital dental technology, more and more patients are choosing medical orthodontics. In recent years, CAD technology has been widely used in the field of orthodontics. The most important aspect of CAD software development and use is obtaining a digital model of the patient's mouth that can be interactively edited by orthodontic designers.

[0003] Due to errors in segmentation and the nature of triangular meshes, existing segmentation algorithms can cause the resulting crown model to include areas that do not belong to the tooth and often have jagged mesh edges. This can affect subsequent processing such as interproximal restorations and virtual root posts. Therefore, the segmented model needs to be optimized to remove excess areas and smooth the mesh edges. However, effective algorithms for this problem are currently lacking, leading to the need for a more automated and robust mesh optimization algorithm. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a three-dimensional crown model optimization method based on geometric information, which solves the existing problems raised in the above background technology.

[0005] In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solution: a three-dimensional crown model optimization method based on geometric information, which can effectively remove redundant model areas caused by area division errors, and at the same time optimize the topological structure of the input model and the size of the model data, which is beneficial to the subsequent processing of the CAD software and improves the efficiency of the front-end and back-end data interaction of the software.

[0006] Specifically, the present invention provides a method for optimizing a three-dimensional crown model based on geometric information, comprising the following steps:

[0007] S1. Input original crown model: The crown model is obtained by segmenting the complete dental model obtained by oral scanning;

[0008] S2. Detect and repair non-manifold vertices: Detect and repair non-manifold vertices on the mesh model;

[0009] S3. Use the quadratic surface fitting method to obtain the magnitude and direction of the vertex principal curvature;

[0010] S31. For each vertex V, construct a Gaussian frame using its normal;

[0011] S32, projecting the vertex and its adjacent vertices onto the frame, and fitting to obtain a quadratic surface Q;

[0012] S33. Use the analytical equation of the quadratic surface Q to calculate the magnitude and direction of the principal curvature of the surface;

[0013] S4, filter vertices by combining the maximum curvature of the vertex and the distance to the edge;

[0014] S5. Delete isolated connected domains of the model: Delete isolated connected domains on the mesh model caused by the operation in step S4;

[0015] S6. Smoothing model edges: Using the position information of adjacent edge vertices to smooth the edges of the processed mesh model;

[0016] S7. Use the isotropic remeshing method to optimize the crown mesh model after smoothing the edges to obtain the final result.

[0017] Optionally, the specific processing method of step S2 is: traverse all vertices of the mesh, count the number n of edges connected to each vertex V, and the vertex with the number n of edges exceeding 2 is neither a manifold vertex, and use the splitting method in the mesh topology operation to process the vertex so that it is split into n / 2 normal vertices located at the same position.

[0018] Optionally, the screening condition of step S4 is: if the maximum curvature of the vertex V exceeds a threshold and is less than 3 facets away from the edge, then the vertex and the adjacent facets are deleted.

[0019] Optionally, each edge vertex b in the edge point set B in step S6 i Calculate the new coordinate b i `=0.25b i-1 +0.5b i +0.25b i+1 , and the process was repeated 5 times.

[0020] The present invention provides a three-dimensional crown model optimization method based on geometric information, which has the following beneficial effects:

[0021] This method combines the geometric features of the crown model and can effectively remove redundant model areas caused by area division errors. At the same time, it optimizes the topological structure of the input model and the size of the model data, which is beneficial to the subsequent processing of the CAD software and improves the efficiency of data interaction between the front-end and back-end of the software. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Flowchart for the implementation of the algorithm of the present invention;

[0023] Figure 2 is the input original crown model image;

[0024] Figure 3This is a schematic diagram of the maximum curvature of the vertex calculated by the quadratic surface fitting method;

[0025] Figure 4 This is the crown model diagram of the final optimization result. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0027] like Figure 1 As shown, the present invention provides a technical solution: a three-dimensional crown model optimization method based on geometric information, comprising the following steps:

[0028] S1. Input original crown model: The crown model is obtained by segmenting the complete dental model obtained by oral scanning;

[0029] S2. Detect and repair non-manifold vertices: Detect and repair non-manifold vertices on the mesh model. Traverse all vertices in the mesh and count the number of edges n connected to each vertex V. Vertices with more than 2 edges n are non-manifold vertices. Use the splitting method in the mesh topology operation to process the vertex and split it into n / 2 normal vertices at the same position.

[0030] S3. Use the quadratic surface fitting method to obtain the magnitude and direction of the vertex principal curvature;

[0031] S31. For each vertex V, construct a Gaussian frame using its normal;

[0032] S32, projecting the vertex and its adjacent vertices onto the frame, and fitting to obtain a quadratic surface Q;

[0033] S33. Use the analytical equation of the quadratic surface Q to calculate the magnitude and direction of the principal curvature of the surface;

[0034] S4. Filter vertices based on their maximum curvature and distance to the edge. If the maximum curvature of a vertex V exceeds a threshold and is less than three facets away from the edge, delete the vertex and its adjacent facets.

[0035] S5. Delete isolated connected domains of the model: Delete isolated connected domains on the mesh model caused by the operation in step S4;

[0036] S6. Smoothing model edges: Use the position information of adjacent edge vertices to smooth the edges of the mesh model. i Calculate the new coordinate b i `=0.25b i-1 +0.5bi +0.25b i+1 , the process is repeated 5 times;

[0037] S7. Use the isotropic remeshing method to optimize the crown mesh model after smoothing the edges to obtain the final result.

[0038] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for optimizing a three-dimensional crown model based on geometric information, comprising the following steps: S1. Input original crown model: The crown model is obtained by segmenting the complete dental model obtained by oral scanning; S2. Detect and repair non-manifold vertices: Detect and repair non-manifold vertices on the mesh model; S3. Use the quadratic surface fitting method to obtain the magnitude and direction of the vertex principal curvature; S31. For each vertex V, construct a Gaussian frame using its normal; S32, projecting the vertex and its adjacent vertices onto the Gaussian frame, and fitting to obtain a quadratic surface Q; S33. Use the analytical equation of the quadratic surface Q to calculate the magnitude and direction of the principal curvature of the surface; S4, filter vertices by combining the maximum curvature of the vertex and the distance to the edge; S5. Delete isolated connected domains of the model: Delete isolated connected domains on the mesh model caused by the operation in step S4; S6. Smoothing model edges: Using the position information of adjacent edge vertices to smooth the edges of the processed mesh model; S7. Use the isotropic remeshing method to optimize the crown mesh model after smoothing the edges to obtain the final result.

2. The method for optimizing a three-dimensional crown model based on geometric information according to claim 1, characterized in that: The specific processing method of step S2 is: traverse all vertices of the mesh, count the number n of edges connected to each vertex V, and the vertex with the number n of edges exceeding 2 is a non-manifold vertex. The vertex is processed using the splitting method in the mesh topology operation to split it into n / 2 normal vertices located at the same position.

3. The method for optimizing a three-dimensional crown model based on geometric information according to claim 1, characterized in that: The screening condition of step S4 is: if the maximum curvature of the vertex V exceeds a threshold and is less than 3 facets away from the edge, then the vertex and the adjacent facets are deleted.

4. The method for optimizing a three-dimensional crown model based on geometric information according to claim 1, wherein: In step S6, each edge vertex b in the edge point set B is i Calculate the new coordinate b i `=0.25b i-1 +0.5b i +0.25b i+1 , and the process was repeated 5 times.

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