Research And Application Of Triangle Mesh Models Transition & Hole Repairing Algorithm

As a geometry model expression, triangle mesh is widely used in many fields such as reverse engineering, finite element analysis, computer animation, 3D medical image reconstruction, etc. In the creating process of the mesh models, there are usually some unpopular holes which are bad for molds'appearance and follow-up treatment. And mesh blending is an important method for editing and designing in the mesh model treatment. Based on substantial literatures and relevant information, this thesis introduces the achievement in triangle mesh models blending& hole repairing algorithm and effective application in CAD/CAM system of dental CAD/CAM. See the central contents as follows:(1)Implement the figure-controlled triangle mesh blending algorithm with the method of blending a parametric with an implicit surface: firstly, transit the rolling balls of parametric surfaces into the triangle mesh models. Then extract the figure-controlled point and establish the implicit surfaces with interpolation between the figure-controlled and blending boundary points by using the variational implicit surfaces. Finally, turn the implicit surfaces to triangle meshes, and complete the blending by the topology and combination of new and old meshes.(2)Analyze the reasons of triangle mesh holes and bring forward various hole repairing algorithms aiming at different hole forms: choose the hole forms with the interactive ways and find out the mesh vertex on the hole boundary while the corresponding algorithm helps to extract the whole hole border line and gain the hole filling surface by interpolating border-controlled points into variational implicit surfaces. Finally, turn the implicit surfaces to triangle meshes, and complete the hole repairing by the topology and combination of new and old hole borders.(3)Apply the above-mentioned algorithms to the field of prosthodontics. There are two steps: a) construct the restoration of maxillectomy defect by using the patients'spiral CT slice data, 3D medical image reconstruction software, reverse engineering software and the transition algorithm and then cast out the titanium mesh dummy with the fast prototype and disappearing molds. b) achieve the teeth mold data with the 3D optical scanner and work out the base of porcelain fused to metal crown based on reverse engineering software and the hole repairing algorithm.