Accelerated walkthrough of large spline models

Abstract

Spline surfaces are routinely used to represent large-scale models for CAD and animation applications. In this paper, we present algorithms for interactive walkthrough of complex NURBS models composed of tens of thousands of patches on current graphics systems. Given a spline model, the algorithm precomputes simplification of a collection of patches and represents them hierarchically. Given a changing viewpoint, the algorithm combines these simplifications with dynamic tessellations to generate appropriate levels of detail. We also propose a system pipeline for parallel implementation on multi-processor configurations. Different components, such as visibility and dynamic tessellation, are divided into independent threads. We describe an implementation of our algorithm and report its performance on an SGI Onyx with RealityEngine2 graphics accelerator and using three R4400 processors. It is able to render models composed of almost than 40,000 Bezier patches at 7-15 frames a second, almost an order of magnitude faster than previously known algorithms and implementations.