Development of virtual tools for direct manipulation of NURBS surfaces in virtual environments
Date
1999
Authors
Perles, Brian Paul
Major Professor
Advisor
Vance, Judy M.
Committee Member
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Abstract
Computer-aided design (CAD) software is an important tool used by engineers during the design process. CAD models are inherently three-dimensional (3D) objects that are difficult to edit with the two-dimensional (2D) based desktop computer interface. Virtual reality (VR) can provide computer input and display devices that have the same number of degrees of freedom as CAD modeling environments. This thesis presents work to solve two of the problems that stand in the way of practical VR interfaces being developed for CAD programs. First, there is little available data on how effective a VR interface is for interacting with CAD data. This thesis describes a human factors study designed to compare subject performance on CAD type tasks when using both desktop computer and VR-based interfaces.
The study has not been conducted with a set of subjects, but the development and testing of the study led to a new understanding of the advantages and problems of VR-based interfaces. The second problem is that there is no available method for adequately controlling free-from surfaces from within a virtual environment that is compatible with current surface representations used in commercial CAD programs. A VR-based surface manipulation program is presented in this thesis. The program allows the editing of NURBS surfaces, a standard in free-form surface representation in CAD packages. The surface is edited using virtual tools and 3D hand motions. Also covered is a technique for maintaining the robustness of constraint-based surface manipulation, the method used to edit the surfaces' control point meshes in the surface manipulation program.
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thesis