Right-triangulated irregular networks

We describe a hierarchical data structure for representing a digital terrain (height field) which contains approximations of the terrain at different levels of detail. The approximations are based on triangulations of the underlying two-dimensional space using right-angled triangles. The methods we discuss permit a single approximation to have a varying level of approximation accuracy across the surface. Thus, for example, the area close to an observer may be represented with greater detail than areas which lie outside their field of view. We discuss the application of this hierarchical data structure to the problem of interactive terrain visualization. We point out some of the advantages of this method in terms of memory usage and speed.