In GRASS 3.1 there was a niffty command which allowed one to use their
mouse to make a regular (or irregular) shaped mask. It seems to be
missing in 4.0. I do not have a digitizer, so was wondering how I
can delineate a polygon to use in masking operations? Certainly
someone out there shares this need. -- Thanks
You can use r.digit. (see grass4.0 manual)
Ronald Wiemer