On Jan 27, 2008, at 9:07 PM, [EMAIL PROTECTED] wrote:
Now what does 'g.region align=' do? Hamish
This one I can answer. When you zoom, g.region has to maintain an integer number of rows and columns. Without -a, it will find the nearest integer for the rows and columns given the extents and resolution specified. Then it will slightly adjust the resolution so that the specified extents are exactly divisible by the calculated integer number or rows and columns.
With -a, g.region will slightly adjust the extents (instead of the resolution) to come up with an integer number or rows and columns as close as possible to the selected extents while exactly maintaining the specified resolution.
Try it by running g.region -ugp after setting a region to specified extents and resolution with and without -a. Without -a, the resolution will differ slightly from those specified, but the extents will exactly match those specified. With -a, the resolution will exactly match and the extents will differ slightly.
However, -a is ignored if the resolution is not specified. I asked that in circumstances where resolution is not specified and -a is used, g.region align to the current resolution, whatever it is.
Michael ____________________ C. Michael Barton, Professor of Anthropology Director of Graduate Studies School of Human Evolution & Social Change Center for Social Dynamics & Complexity Arizona State University Phone: 480-965-6262 Fax: 480-965-7671 www: <www.public.asu.edu/~cmbarton> _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev
