[STATSGRASS] isolines

[Hamish]

> I am new to this list. Does anyone know a package with I can use to
> plot isolines based on hydrologic triangles?
> I want to draw ground water isolines.


GRASS has limited support for TINs, you would have to extract values at
the nodes (v.in.ogr? -> vector points), interpolate to a raster map
using splines (v.surf.rst), then create vector isolines with r.contour.

FWIW, this will probably give you better results than direct TIN->
isolines. e.g. I think the way Arc does it is to overlay a raster grid
on the TIN and then interpolate (linear) the value at each grid point.


GRASS NVIZ examples:
  http://grass.ibiblio.org/grass60/screenshots/images/nviz_isosurf3d.jpg
  http://skagit.meas.ncsu.edu/~helena/gmslab/

see also v.vol.rst module (3D grid raster support):
  http://grass.ibiblio.org/grass60/manuals/html60_user/v.vol.rst.html


see also Vis5D+ software:
  http://www.ssec.wisc.edu/~billh/vis5d.gif
  http://vis5d.sourceforge.net



Hamish