language: en

View-Dependent Simplification Of Arbitrary Polygonal Environments

David Luebke, Carl Erikson
Department of Computer Science University of North Carolina at Chapel Hill

1. ABSTRACT Hierarchical dynamic simplification (HDS) is a new approach to the problem of simplifying arbitrary polygonal environments. HDS operates dynamically, retessellating the scene continuously as the users viewing position shifts, and adaptively, processing the entire database without first decomposing the environment into individual objects. The resulting system allows real-time display of very complex polygonal CAD models consisting of thousands of parts and hundreds of thousands of polygons. HDS supports various preprocessing algorithms and various runtime criteria, providing a general framework for dynamic view-dependent simplification. Briefly, HDS works by clustering vertices together in a hierarchical fashion. The simplification process continuously queries this hierarchy to generate a scene containing only those polygons that are important from the current viewpoint. When the volume of space associated with a vertex cluster occupies less than a userspecified amount of the screen, all vertices within that cluster are collapsed together and degenerate polygons filtered out. HDS maintains an active list of visible polygons for rendering. Since frame-to-frame movements typically involve small changes in viewpoint, and therefore modify the active list by only a few polygons, the method takes advantage of temporal coherence for greater speed.

CR Categories: I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling - surfaces and object representations. Additional Keywords: polygonal simplification, level of detail, view dependent rendering.

2. INTRODUCTION