Malcolm,
I think the DRGs are just TIFF files. I imported one
once but I don't remember if I used r.in.tiff or converted
to ppm then used r.in.ppm, but the georeferencing had to
be done manually, and if I had to convert I'm sure I nearly
filled a disk! So some kind of import program that would
use the file directly and georeference automatically would be
great.
- Bill