Methods for Computer-Aided Design of Free-Form Objects

摘要

A set of B spline modeling and visualization methods was developed to supportinteractive free form shape design with the computer. The swinging method is described as a free form generalization of the standard rotational sweep. The projection curve method facilitates surface skimming construction by plane curve interaction. A variety of tools for local surface interaction is presented, including the B2 spline representation as an interface to smooth curve and surface interpolation. A complete algorithm for ray tracing parametric surfaces is described. The adaptive zero eye subdivision method is presented for efficient detection of ray intersection, with parametric surfaces. The overall amount of ray tracing computation is reduced by utilizing coherence properties with a novel method called shadow image buffers. The methods described form the core of a computer aided design system used in different industrial applications.