Efficient Ray Intersection for Visualization and Navigation of Global Terrain using Spheroidal Height-Augmented Quadtrees

Abstract

We present an algorithm for efficiently computing ray intersections with multi-resolution global terrain partitioned by spheroidal height-augmented quadtrees. While previous methods support terrain defined on a Cartesian coordinate system, our methods support terrain defined on a two-parameter ellipsoidal coordinate system. This curvilinear system is necessary for an accurate model of global terrain. Supporting multi-resolution terrain and quadtrees on this curvilinear coordinate system raises a surprising number of complications. We describe the complexities and present solutions. The final algorithm is suited for interactive terrain selection, collision detection and simple LOS (line-of-site) queries on global terrain.