Ivan - instead of using the small threshold that is killing it, if
you need just the stream network use arbitrarily large threshold and
derive your stream network from the accum file like this
r.mapcalc "mystreams=if(abs(myaccum)>30,1,null())"
or you can use abs(myaccum) instead of 1 if you need contributing
area for each stream cell.
(isn't this in the man page? I have been doing it that way for years)
Helena
On Mar 19, 2008, at 10:43 AM, ivan marchesini wrote:
Hi Hamish...
yes.. my threshold is really small (30 cells, because I need a very
detailed stream network in output), and this can probably have a
strong
effect on the time of analysis...
However I'm really surprised of your results with 170000000 of
cells...
and 2 Gb of ram...!!
really impressive...
I have tried over two different computers (with 2 Gb of ram), but the
result is the same... so I think that the problem is not on the
quality
of the ram or other similar thinks but on the dimension of the
dataset...
I will try with different resolution as soon as possible... but at the
end I need this resolution because I have "cleaned" the dem with
v.breach to obtain a hydrologically correct dem and now I must use
this
dem to derive the drainage...
Many thanks for your interest....
Ivan
Il giorno mar, 18/03/2008 alle 18.05 -0700, Hamish ha scritto:
e region slightly or
run with a slightly coarser resolution to see where the memory limit
is?
--
Ti prego di cercare di non inviarmi files .dwg, .doc, .xls, .ppt.
Preferisco formati liberi.
Please try to avoid to send me .dwg, .doc, .xls, .ppt files.
I prefer free formats.
http://it.wikipedia.org/wiki/Formato_aperto
http://en.wikipedia.org/wiki/Open_format
Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a
06125
Perugia (Italy)
Socio fondatore GFOSS "Geospatial Free and Open Source Software"
http://www.gfoss.it
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