High Speed and High Fidelity Visualization of Complex CSG Models

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. As a part of pre-processing, we compute the Brep (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. Given a trimmed spline model, we tessellate it into polygons as a function of the viewing parameters and render it using visibility culling and coherence between successive frames. The choice of a analytic representation of the model and the trimming curves is 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.