Iterative TIN generation from digital evaluation models

A technique for producing a triangulated irregular network (TIN) from a digital elevation model (DEM) is described. The overall goal is to produce an approximate terrain description that preserves the major topographic features using a greatly reduced set of points selected from the original DEM. The TIN generation process is iterative; at each iteration, areas in the DEM that lie outside of a user-supplied error tolerance in the TIN are identified, and points are chosen from the DEM to more accurately model these areas. Point selection involves the computation of the difference between the actual DEM and an approximate DEM. This approximate DEM is calculated by interpolating elevation points from the TIN