A Visibility Sphere Marching algorithm of constructing polyhedral models for haptic sculpting and product prototyping

This paper presents a Visibility Sphere Marching algorithm of constructing polyhedral models from Dexel volume models for haptic virtual sculpting. Dexel volume models are used as the in-process models representation during interactive modification in a haptic virtual sculpting system. The stock material represented in a Dexel volume model is sculpted into a designed model using a developed haptic sculpting system. The sculpted Dexel volume models are converted to polyhedral surface models in STL format by the proposed visibility sphere marching algorithm. The conversion turns out to be an interesting and challenging problem. The proposed visibility sphere marching algorithm consists of three sub-algorithms: (i) roof and floor covering, (ii) wall-building, and (iii) hole-filling algorithms. The polyhedral surface models converted from the Dexel volume models can then be input to and processed by available computer-aided manufacturing (CAM) or rapid prototyping systems. The presented technique can be used in virtual sculpting, CAD/CAM, numerically controlled machining verification and rapid prototyping.