[GRASS-user] r.watershed error

[Markus Metz]

On Sun, May 23, 2010 at 8:10 PM, Kurt Springs <ferret_bard at mac.com> wrote:
> Problem was the resolution it starts working when I set it to 100m.  The dem
> is ~69 x 27 km.

Apparently, the dem has a resolution of 1/3 arcsec (~10m), maybe
reprojected and resampled. With these extends, there would be about
186 million cells in the input map which is not a lot. I have
successfully processed regions with ~250 million cells in memory and
~500 million cells in segmented mode. Make sure the current
computational region matches the resolution of the input dem and the
extends of the current computational region do not exceed the extends
of the input map. Setting the computational region to a smaller area
within the dem coverage is fine, as long as g.region -p align=NED13_01
is used after adjusting the extends. A resolution of 100m throws away
a lot of the information present in the original dem.


> Thanks
> On May 23, 2010, at 12:00 PM, Rich Shepard wrote:
>
> On Sat, 22 May 2010, Kurt Springs wrote:
>
> ERROR: G_malloc: unable to allocate 18446744070980740804 bytes at ...
>
>                                       ^^^^^^^^^^^^^^^^^^^^
>
> Any idea what I'm doing wrong?
>
> Kurt,
>
>   Look at the amount of memory your file wants to be allocated: several
> Petabytes. How much area is covered by that DEM and at what resolution? Even
> with GRASS compiled for large file support your file is _way_ too large.
>
> Rich
>
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