Fast Display of Complex CSG Models

Subodh Kumar    Shankar Krishnan     Dinesh Manocha     Atul Narkhede
Department of Computer Science
University of North Carolina
Chapel Hill NC 27599


We present a system for fast and accurate display of CSG (constructive solid geometry) models. Such models have as primitives, polyhedra and solids whose boundaries can be represented using rational spline surfaces. %The latter set includes cones, spheres, tori, solids of %revolution, prisms, pyramids etc. As part of pre-processing, we compute the B-rep (boundary representation) from the CSG tree and represent the resulting solid using trimmed spline surfaces. No assumptions are made on the number of primitives or the degree of the primitives in the CSG tree. We also present an accurate, efficient and multiresolution representation of the high degree trimming curves. Given a trimmed spline model, we tessellate it into polygons as a function of the viewing parameters and render it using visibility computations and coherence between successive frames. The choice of a multiresolution representation of the model and the trimming curves is {\em fundamental} to the fast performance of the system. The system has been used to convert parts of a submarine storage and handling system model represented as more than $2,000$ CSG trees. The B-rep consists of more than $30,000$ trimmed spline surfaces and is displayed at interactive rates on the Pixel-Planes 5 graphics system. _______________________________
Supported by DARPA ISTO Order No. A410, ONR Contract N00014-94-1-0738, NSF Grant No. MIP-9306208, Junior Faculty Award, University Research Award, NSF Grant CCR-9319957, ARPA Contract DABT63-93-C-0048 and NSF/ARPA Science and Technology Center for Computer Graphics and Scientific Visualization, and NSF Prime Contract No. 8920219.