Research On Mechanical CAD Model Simplification Of Maintaining Boundary Features

In this paper, according to the reason that the triangular mesh simplification algorithm inthe existing general-purpose field does not apply to simplify the mechanical CAD meshmodels with the obvious boundary contour curve features, analysis the features of mechanicalCAD mesh model, and put forward a simplification algorithm which can better maintain theoverall contour shape features of the mechanical CAD model.Firstly, to deal with the different formats of mechanical CAD models, access to thetriangular mesh model of the original model. PLY file format is a simple data structure, easyto read and so on, as well as use Metro tool to assess the simplification models in the Chapter5which supports the Ply format, so we choose the mechanical CAD model deal with into thePLY format.Secondly adopt the mesh surface segmentation technique to extract the various boundarycontour curves on the mesh surface which determines the visual perception. According totriangular mesh of the mechanical CAD mesh model surface distributes uneven density, thearea of the triangle mesh is different and so on, as well as the respective advantages anddisadvantages of segmentation methods which based on the edge and the vertices, in thispaper, use the hybrid segmentation method which simultaneously based on edge and vertex,segments the surface of the mechanical CAD mesh, to obtain a more satisfactorysegmentation results.Finally, analyze the advantages and disadvantages of the original QEM algorithm, aswell as why does not apply to simplify the mechanical CAD mesh models, improves the QEMalgorithm: put the segmentation results which obtained through using the hybrid segmentationmethod based on edge and vertex to split mechanical CAD mesh surface as the foundation,divides the edges of segmentation result into four categories, namely, contour edge,transitionedge, cross-border edge as well as general edge, and using the QEM algorithm simplify thesefour categories with the different strategy,to simplify the overall of the3D mechanical CADmesh model. In order to obtain segmentation results which better able to maintain the boundary contour feature of the model, reflect the superiority of this improved algorithmmore intuitively.In the last part of the paper, combine the relevant information of mechanical CADmodels simplification, develop a system which is suitable for simplifying mechanical CADmodels, and implement visualization of the model simplification process, and simplifymultiple sets of3D mechanical CAD model, comparison with the simplification results of theoriginal QEM algorithm, we can see that simplification results obtained throughsimplification method introduced in this paper to simplify the3D mechanical CAD mode,which is better than simplification results of the original QEM algorithm on maintaining theoverall contour features and preserving the holes and other topological structures of theoriginal mesh models, and there is a greater degree of reduction in the overall modelsimplification error.