Research On Methods For Removing Pseudo Elements And Decision-Making In Constructing 3D Solids From 2D Views

The reconstruction of 3D solid model from 2D orthographic views has been a key technology and a major research issue in CAD/CAM. This thesis develops research on efficiency issue for reconstruction based on the B-rep method. It primarily resolves low efficiency issue of judging and removing pseudo elements and decision-making. Achievements obtained are as follows:1.For the low efficiency of removing pseudo elements in the wire-frame, according to the broken lines in 2D views, the topological information and the relationship between the 2D information and the 3D information generated in construction, we give some definitions and propose some related theorems which have been proved correct. Basing on them, we propose a new algorithm of removing pseudo elements by which we can ensure the candidate edge generated by the broken line in 2D views is pseudo element if it is inside of the face which can be seen completely. At last delete other pseudo elements by the topological information of former methods.2.For the low efficiency and bad capability of disposing multi-solutions of the decision-making after generating face loops, we thoroughly analyzed the former divide-conquer algorithm and decision-chaining algorithm. We propose a reformed decision-making algorithm based on the two algorithms and provide the particular process. Not only coming into their merits, but also avoiding their deficiencies. 3.Having designed and developed the reconstruction of Automobile mold on the Gems system platform, and completed its two menus for removing pseudo elements and decision-making.In conclusion, the algorithm of removing pseudo elements can reduce the number of face loops generated and the searching space of the decision-making. Compared with former methods, our method can reduce the execute-time mostly, and also can delete pseudo elements generated by the broken lines in more cases. The decision-making algorithm can efficiently get a solution satisfying orthographic views and truly deal with multi-solutions.