On Tue, 10 Jul 2018, Huidae Cho wrote:
g.region creates a rectangular computational region while r.mask can create an irregular mask. If you use r.mask, any cells outside the mask will be ignored, so you have to make sure that your mask is big enough to cover your basin. In terms of computational time, r.mask can be faster depending on what modules you need. For example, when you run flow accumulation, you may save some time using r.mask because you don't have to calculate flow accumulation outside your area of interest. If you use g.region that covers your basin, you calculate flow accumulation outside the basin within the rectangular region. So in general, I would say r.mask is preferred if and only if the mask is correct.
Huidae, This is a perfect answer as it covers all the important differences between the two. Thanks very much for the lesson. Regards, Rich _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
