Method for fairing product STL (Standard Template Library) model based on molded surface feature approximation

Abstract

The invention discloses a method for fairing a product STL (Standard Template Library) model based on molded surface feature approximation, belonging to the technical field of reverse engineering. The method comprises the following steps: firstly, using a curve shape-preserving simplifying method to extract a molded surface feature grid of a product STL model; then, constructing a G1 continuous Bezier piecewise curved surface according to the molded surface feature; and finally, using the G1 continuous Bezier piecewise curve as a fairing reference curved surface of the product STL model, and regulating the vertex of the product STL model to the reference curved surface, so that the fairing treatment of the product STL model is achieved. The method can quickly acquire an integral fairing result of the STL model when detail features of the product STL model are kept.

Description

technical field [0001] The invention provides a product STL model smoothing method based on surface feature approximation, which belongs to the technical field of reverse engineering. Background technique [0002] In the field of product reverse engineering, product STL models are usually used to represent the results of surface topology reconstruction of scattered point clouds. Due to factors such as environmental vibration, human disturbance, and 3D scanning equipment's own precision defects, there are local disturbances and noises in the measurement point cloud data, and the product STL model generated by this type of point cloud interpolation has low smoothness and accuracy. In order to improve the accuracy of surface reconstruction, it is necessary to optimize the smoothing of the product STL model. [0003] Searching for existing technologies found that Shenhuicun et al. published a paper on the academic journal "Journal of Nanjing University of Aeronautics and Astron...

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Problems solved by technology

[0003] Searching for existing technologies found that Shenhuicun et al. published a paper on the academic journal "Journal of Nanjing University of Aeronautics and Astronautics" 2004, 36(4), P471-476 "Research on Adaptive Fairing of Surface Triangular Mesh Model Based on Vertex Classification In ", the normal vector of the grid vertex is calculated according to the grid unit and the normal vector of the neighborhood, and the weighted combination vector of the Laplace smoothing vector and the normal vector of this point is used as the vertex adjustment direction, and the iterative adjustment is performed by setting the accuracy threshold The position of the vertices of the mesh, this method is prone to produce an over-smooth mesh with loss of surface details, poor shape retention, and low algorithm operation efficiency

[0004] In the paper "Mesh Smoothing with Uniform Principal Curvature" published in the academic journal "Journal of Computer Science" 2004, 27(1), P79-84, Liu Shenglan and others estimated the grid by constructing a local quadratic reference surface of the grid surface For the main curvature value of the vertex, the weighted average method is used to solve the vertex curvature value, and the position of the mesh vertex is adjusted according to the curvature value and the quadratic surface equation. The local reference surfaces constructed by this method lack continuity, resulting in poor overall smoothing effect

[0005] To sum up, the existing product STL model smoothing methods cannot well realize the overall smoothing of the product STL model, and it is difficult to effectively preserve the surface detail features

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