DESCRIPTION
r3.mask facilitates the creation of a raster3d
"MASK" map to control raster3d operations.
The raster3d map is used as the reference map.
Cells in the mask are marked as "mask out" if the corresponding cell in
map contains a value in the range specified with maskvalues.
NOTES
Before a new 3D-mask can be created the existing mask has to be removed
with g.remove.
SEE ALSO
g.remove
AUTHORS
Roman Waupotitsch, Michael Shapiro,
Helena Mitasova, Bill Brown, Lubos Mitas,
Jaro Hofierka