Using constraints in Delaunay and greedy triangulation for contour lines improvement

Automatic computation of contour lines on a triangulation is a difficult problem because due to input data digitization and the type of triangulation used, some triangles can be a source of a strange behaviour of the contour lines. In this paper, we show what problems can appear in contour lines when Delaunay or greedy triangulations are used and how the contour lines can be improved using constraints in the triangulation. We improved contour lines by manually imposing constraints in a triangulation editing program. Automation of this process is a next step of our work.