Structural lines for triangulations of terrain

To build triangulated approximations to terrain surfaces from dense elevation models, we find structural lines for the initial skeleton of the triangulation. We describe the surfaces as regions; the spines of these regions are the structural lines on the surface. We use these lines as a skeleton of the surface, points and edges that initialize the triangulation. Simple local curvature analysis of the terrain results in many lines whose significance is only local. We show how the curvature analysis can be extended to find local regions around the structural lines. We use various properties of the regions to assign a significance to the lines, to rank them for inclusion in the skeleton. We then use the lines to approximate the surface with a compact triangulation