Interactive Multiresolution Editing and Display of Large Terrains

In recent years, many systems have been developed for the real-time display of very large terrains. While many of these techniques combine high-quality rendering with impressive performance, most make the fundamental assumption that the terrain is represented by a fixed height map that cannot be altered at run time. Such systems frequently rely on extensive preprocessing of the raw terrain data. They are mostly designed for maximum performance. Consequently, these techniques are ill-suited for the many applications such as geological simulations and games in which terrain surfaces must be altered interactively. We present a two-component system that can achieve real-time view-dependent rendering while allowing on-line multiresolution alterations of a large terrain. Our fundamental height map representation is a wavelet quadtree hierarchy, allowing one to easily apply arbitrary multiresolution edits to the terrain. Our display algorithm extracts a view-dependent approximation of the terrain from the wavelet quadtree in real time. The algorithm dynamically alters this approximation based on any ongoing edits. To allow for flexibility and to limit performance loss, the two components of this system have been designed to be as independent as possible.