3D in GRASS

Hello.

I would know if images from
http://www2.gis.uiuc.edu:2280/modviz/gsoils/ccsoil2.html
are made using G3D in GRASS.

Another question is, how can I represent discret objects using G3D? I have
to develop a project in which the soil horizons must be clear. I need to
know if a point in x,y,z coordinates is in a stratum or another. This
stratum could have irregular surfaces.

I think to have a 3D raster in which I say that a voxel is of one
material. How could I obtain this discret boundaries from a set of points
of this object. The commands from GRASS use interpolation, so I would
obtain soft variation of values in voxels, isn't it?

To visualize the objects, I can't use NVIZ, because the GUI has to be
personalized to the application. Could I use the code from NVIZ to do
this?

Thanks.

--
------------------------------------------------------------------------

  ########### ############# ###########
       # Carlos Martínez Burgos # #
       # cmarbur@iti.upv.es # #
       # Ingeniero Informático # #
       # Instituto Tecnológico de Informática # #
       # Universitat Politècnica de València # #
  ################ # ###########

------------------------------------------------------------------------