Moritz Lennert wrote: > >> Thanks for your reply. In fact I need to generate a (uncontroled) distance > >> map from all my values=1. > >> I confess that I don´t understood how r.grow will help me on this task. > >> I need to build a for looping and grow and grow many times the new > >> generated > >> map? > >> Or is there a a way of simple generate a distance map on one command? > > > > "r.grow ... in=1 out=2" has the same effect as r.buffer with a single > > distance, except that r.grow's radius= option is measured in cells > > while r.buffer's distance= option is measured in physical units (e.g. > > metres). > > > > You can get the same effect as r.buffer with multiple distances by > > running r.grow once for each distance value, then overlaying the > > results, from largest to smallest buffer size. > > > > r.grow will be quite a bit slower, particularly for large distances, > > but it doesn't require that the map fits into memory. > > > > Alternatively, you could reduce the resolution, so that the map fits > > into memory. Or you could run r.buffer on smaller sections of the > > data, then merge the results with "r.series method=minimum". > > Not sure I understand correctly what you are trying to do, but maybe you > could use r.cost on a map with cell value = resolution and with your > binary map as starting points (start_rast) ?
Note that r.cost will produce polygonal buffers rather than circles, and it's also likely to be quite slow. More significantly, I don't know whether it will handle a map that large. It relies upon the segment library, which doesn't appear to have large file support enabled. -- Glynn Clements <[EMAIL PROTECTED]> _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
