NURBS Surface Shaping in a Virtual Reality Environment

A. Liverani and G. Piraccini (Italy)


CAD, Surface modelling, Virtual Reality, Spatial Tracking, 3D interface.


The use of 3D tracking systems in a Virtual Reality environment may definitely change CAD interfaces and free-form surface modelling. In this paper an original method for full 3D interactive surface shaping and modifying is described. VISM (Virtual Integrated Surface Modeller) has been developed with the leading idea that 3D tracking system can dramatically speed up modelling sessions. On the opposite of a W-I-M-P (Windows-Icons Menu-Pointer), paradigm common to most current CAD systems, VISM demonstrates that Virtual Reality devices can manage all types of surface in a unique shape generative action. Unlike "Virtual Clay" based and "Metaball" modelling techniques, VISM both wants to give to engineers and designers a more intuitive and natural tool to get 3D shapes. Based on Polhemus Fastrak and stereoscopic vision, VISM doesn't provide icons to the designer, leading to a "null icons" and "null menu" full 3D interface. The new interface is fully implemented on bi-manual input system on top of a Virtual Reality environment. The entity grabbing is also supported by pinch-enabled gloves. The designer exploits a NURBS curve tool to deform a NURBS surface and extracts drive curve direction from his right hand movement. The curve tool may be also real time deformed with left hand through node-control point repositioning. Furthermore the modeller is fully implemented using NURBS curves and surfaces and a fast surface-over-curve positioning and deformation has been implemented, replacing both traditional snapping and picking activities.

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