| Abstract | Over the past decade, B-spline modeling has become the standard mathematical model for representing freeform or organic objects in CAD/CAM systems. Using a Bspline surface to represent the virtual model in a haptic concept design module helps to streamline the exchange of the information with existing CAD/CAM systems. Bspline surfaces also help increase visual realism because these represent continuous surface. At the same time, physically based virtual deformable models provide a sense of realism to the user. However, the algorithms used for interaction with the virtual model should be efficient to maintain acceptable level of virtual realism and perceive the simulation as continuous with no time lag. This paper presents a B-spline surface based concept design framework, which can be used to generate various concepts, evaluate these concepts, and provide user training. The proposed framework assumes that all deformable models are represented as B-spline surfaces. The tools used to interact with the deformable models can be implicit surface, tessellated surface, Bspline surface, or point-based. The technique exploits blending matrices for the Bspline surface that are independent of the control point positions and, hence, can be pre-calculated prior to haptic interaction. Once determined, the pre-calculated blending matrices are used to generate discrete points on the B-spline surface. Mass spring system is used to incorporate material properties to the virtual objects. Practical illustrations of the concept design framework are presented for modeling and evaluation of concepts and provide training to the intended user segment. |
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