Hi,
Delanauy triangulation is a well known algorithme for terrin modelling. You can found some ressources here (Librarys that you can use in your own software if you are a programer):
http://local.wasp.uwa.edu.au/~pbourke/modelling/triangulate/
http://www.ncgia.ucsb.edu/conf/SANTA_FE_CD-ROM/sf_papers/lattuada_roberto/paper.html
http://www.mathtools.net/C_C__/Computational_geometry/
http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Triangulation_3/Chapter_main.html
www.vtk.org/
or some softwares :
http://www.comp.nus.edu.sg/~shixinwe/software.htm
http://www.qhull.org/
I'll chech for other softwares and let you know.