A novel haptics-based interface and sculpting system for physics-based geometric design

Conventional geometric design techniques based on B-splines and NURBS often require tedious control-point manipulation and/or painstaking constraint specification via unnatural mouse-based computer interfaces. In this paper, we propose a novel and natural haptic interface and present a physics-based geometric modeling approach that facilitates interactive sculpting of spline-based virtual material. Using the PHANToM haptic device, modelers can feel the physically realistic presence of virtual spline objects and interactively deform virtual materials with force feedback throughout the design process. We develop various haptic sculpting tools to expedite the deformation of B-spline surfaces with haptic feedback and constraints. The most significant contribution of this paper is that point, normal, and curvature constraints can be specified interactively and modified naturally using forces. To achieve the real-time sculpting performance, we devise a novel dual representation for B-spline surfaces in both physical and mathematical space: the physics-based mass-spring model is mathematically constrained by the B-spline surface throughout the sculpting session. We envision that the integration of haptics with traditional computer-aided design makes it possible to realize all the potential offered by both haptic sculpting and physics-based modeling in CAD/CAM, virtual prototyping, human-computer interface, and medical training and simulation. (C) 2001 Elsevier Science Ltd. All rights reserved.