[GRASS-user] cutting a 3d volume with a 2d surface

[Markus Neteler]

On Wed, May 26, 2010 at 7:50 PM, Carlos Grohmann
<carlos.grohmann at gmail.com> wrote:
> Dears, can I "cut" a 3d volume using a 2d (ok, 2.5d) surface?

Do you mean this?
http://grass.osgeo.org/grass64/manuals/html64_user/r3.cross.rast.html

> interpolating wir r3.* gives me the results inside a rectangular
> prism. can I use a surface (like topography) to remove the upper part
> of the volume?

.. sounds more like a job for r3.mapcalc...

Markus