There is not any professional program on internet like this, and you can get it without any effort. I think this could be a handicap because it's dificult to believe, but it's true!; try it and you'll surprise you. It's not only a program to calculate a delaunay triangulation but you can insert break-lines to get a representation of the real terrain. In this thecnical document, written by Severin Cazanescu for a conference, we can learn how LanDTM apply the delaunay triangulation principles.