[GRASS-user] DTM/DEM to TIN

[Jeshua Lacock]

Hi Giovanni,

A module for this would be really neat! I am not sure if this will be helpful, but here is what I have done in the past.

Set your region of interest of course. My notes indicate that I had to add an extra unit to the north and west region (not sure why).

r.out.vtk -v input=dem at PERMANENT output=dem.vtk elevation=dem at PERMANENT

# 'preserve normals' option kills Meshlab with DEM!

r.out.vtk -v input=dem at PERMANENT output=dem.vtk elevation=dem at PERMANENT

I then open dem.vtk in Paraview, and run the Delaney 2D filter (default options) save as .PLY file.

Next I open the resulting .PLY file in Meshlab and run Quadric based edge collapse strategy - specify desired triangles, preserve normals and I save as .OBJ file. For my needs I choose  "Preserve boundary of mesh”.


Cheers,

Jeshua Lacock
Founder/Engineer
3DTOPO Incorporated
<http://3DTOPO.com>
Phone: 208.462.4171