On the study of converting CAD models into Triangular models

• Main Authors: Yu-hung Yang, 楊聿宏
• Other Authors: Jing-yi Lai
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/bqbg38

碩士 === 國立中央大學 === 光機電工程研究所 === 97 === All types of the models could be structured by triangle meshes which have been widely used in CAD/CAM systems, computer graphics, medical images, Virtual Reality, etc. For applications of the reverse engineering and the rapid prototyping processes, the converting CAD models into triangular meshes is a very important technique. Keeping the accuracy is the prerequisite for the process of the model structuring, or the result triangular meshes can’t be indicated the original CAD model. Reducing the triangular mesh quantity of the model is another important procedure. Excess triangle meshes would make the efficiency of data programming be reduced. We provide an exactly and efficiently accurate controlling method and the surface subdivision method assisted by the quadtree data structure which would help to reduce the amounts of meshes. In order to structure the watertight and manifold triangular mesh, we provide the applications of the B-Rep data structure to help the trimmed NURBS surfaces establish the relationships of boundaries between surface and surface. When the CAD model structured by trimmed surfaces has been triangulated, the triangle meshes in the boundary connecting with neighbor surfaces would be structured exactly. The wrong cases such as holes or self-intersection would not be occurred. Therefore, the ideal polygon-based model has been structured.