Structural Lines, TINs, and DEMs

The standard method of building compact triangulated surface approximations to terrain surfaces (TINs) from dense digital elevation models (DEMs) adds points to an initial sparse triangulation or removes points from a dense initial mesh. Instead, we find structural lines to act as the initial skeleton of the triangulation. These lines are based on local curvature of the surface, not on the flow of water. We build TINs from DEMs with points and structural lines. These experiments show that initializing the TIN with structural lines at the correct scale creates a TIN with fewer points given a particular approximation error. Structural lines are especially effective for small numbers of points and correspondingly rougher approximations. Received December 21, 1995; revised September 24, 1999.