[GRASSLIST:724] problems with MASK

[andrea.iescheck at ufpr.br]

Hi

I´ve been trying to create a mask in order to visualize the area where my
data were collected.
I´ve made a mask that represents the boundary of this area using r.digit.
The mask is a raster map with value 1 (inside the area) and NULL (outside
the area).
With mapcalculator I´ve made the product of  the mask and the interpolated
surface of my datafile. Also I used this mask as the raster file mask to
generate the grid 3d file of my data.
It works when I visualize the surfaces in grass but it doesn´t work
properly when I try to visualize the volume (isosurfaces) with nviz - the
isosurfaces don´t cover the hole area just a part of it.
I`ve made a lot of tries but the results are almost the same.
Is there another way to create this mask?
I would appreciate if someone could help me.

Thanks a lot
Andrea