VIRTUAL-REALITY INTERFACES FOR FEATURE-BASED COMPUTER-AIDED-DESIGN SYSTEMS

A computer-aided design (CAD) system with a virtual reality (VR) inter face simplifies the design of complex mechanical parts. To add a desig n feature (e.g., a hole, slot, or protrusion), the designer can naviga te in the part to the appropriate face of the part where he/she wishes to attach the feature, and sketch directly on that face. Besides conv enience, this method of feature specification implicitly enforces feat ure accessibility constraints, and also provides hints to the process- planner regarding the order in which the features may be manufactured. We detail the design of a VR-based prototype CAD system. The system m aintains the knowledge of part cavities and their adjacencies, and a t riangulated boundary-representation of an approximating polyhedron. We present incremental provably correct algorithms for updating this rep resentation as the user edits the part. We also show how this represen tation supports real-time displays, navigation, and collision detectio n. The user-interface of the CAD system relies on these capabilities t o provide the above-mentioned advantages. (C) 1997 Elsevier Science Lt d.