grid2tri - Gridded Surface to Irregular Triangulation

Creates an irregular triangulation of a gridded surface, possibly with undefined areas

Converts a regular gridded surface into an irregular triangulation by iteratively adding vertices to an initial triangulation until the difference is smaller than some user set tolerance(s). Returns a triangulation interpolant that can be evaluated on scattered or gridded query locations. The size of a triangulation interpolant is usually much smaller than the corresponding gridded interpolant as the triangulation is adapted to surface, i.e., the resolution is not uniform but finer in areas where needed.
The routines support triangulation of gridded surfaces with undefined NaN-areas (for example holes) and “hot-start” to refine a previous triangulation. There are a number of options for the triangulation, for the error tolerances/convergence criteria and for printing/plotting. All files have detailed help and demos are included.
The routines are, for example, useful for converting GIS data from DEM- to TIN-format and for converting gridded data to a triangulation that can be used in a PDE solver.