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 s pecification 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 spli ne-based virtual material. Using the PHANToM haptic device, modelers can fe el the physically realistic presence of virtual spline objects and interact ively deform virtual materials with force feedback throughout the design pr ocess. We develop various haptic sculpting tools to expedite the deformatio n of B-spline surfaces with haptic feedback and constraints. The most signi ficant contribution of this paper is that point, normal, and curvature cons traints can be specified interactively and modified naturally using forces. To achieve the real-time sculpting performance, we devise a novel dual rep resentation 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 integ ration of haptics with traditional computer-aided design makes it possible to realize all the potential offered by both haptic sculpting and physics-b ased modeling in CAD/CAM, virtual prototyping, human-computer interface, an d medical training and simulation. (C) 2001 Elsevier Science Ltd. All right s reserved.