Terrain rendering using GPU-based geometry clipmaps

Abstract: The geometry clipmap introduced in Losasso and Hoppe 2004 is a new level-of-detail structure for rendering terrains. It caches terrain geometry in a set of nested regular grids, which are incrementally shifted as the viewer moves. The grid structure provides a number of benefits over previous irregular-mesh techniques: simplicity of data structures, smooth visual transitions, steady rendering rate, graceful degradation, efficient compression, and runtime detail synthesis. In this chapter, we describe a GPU-based implementation of geometry clipmaps, enabled by vertex textures. By processing terrain geometry as a set of images, we can perform nearly all computations on the GPU itself, thereby reducing CPU load. The technique is easy to implement, and allows interactive flight over a 20-billion-sample grid of the United States stored in just 355 MB of memory, at around 90 frames per second.