More and more products with complex geometries are being designed and manufactured by computer aided design (CAD) and rapid prototyping (RP) technologies. Freeform surface is a geometrical feature widely used in modern products like car bodies, airfoils and turbine blades as well as in aesthetic artifacts. How to efficiently design and generate digital prototypes with freeform surfaces is an important issue in CAD. This paper presents the development of a Virtual Sculpting system and addresses the issues of surface reconstruction from dexel data structures and freeform geometric modeling using the level-set method from distance field structure. Our virtual sculpting method is based on the metaphor of carving a solid block into a 3D freeform object using a 3D haptic input device integrated with the computer visualization. This dissertation presents the result of this study and consists primarily of four papers. The first paper presents the development of a novel contour generation algorithm for the purpose of visualizing the sculpted dexel models and interfacing with other CAD/CAM/CAE systems. To improve the sampling quality of the dexel model used in the virtual sculpting system, the second paper develops a triple-dexel structure and a novel surface reconstruction method from triple-dexel data. The developed surface reconstruction method is faster than the voxel-based method, and the reconstructed surface model is more accurate than surface reconstructed from voxel representation using the marching cube algorithm. To enhance the modeling capability of the virtual sculpting system, additional freeform modeling operations including deformation, smoothing and imprint are developed using the user's gesture inputs based on the level-set method. The developed operations generate a watertight mesh model effective for freeform geometric modeling.Virtual prototypes are particularly beneficial to the firms that have never developed similar products before, since the firms can avoid expensive costs investing in tooling and in developing manufacturing processes for physical prototypes.
|Title||:||Virtual Prototyping with Surface Reconstruction and Freeform Geometric Modeling Using Level-set Method|
|Publisher||:||ProQuest - 2008|