[GRASS-user] r.watershed and big files

[Markus Neteler]

On Thu, Sep 1, 2011 at 4:07 PM, Arno Gerretsen <arno at agerrius.nl> wrote:
...
> I did another attempt to use r.watershed on my big file. This time I
> compiled GRASS 6.4.1 from source code and made sure it was configured for
> largefiles (--enable-largefile).

I tried myself with GRASS 6.4.2.svn (note that you have 6.4.1). That may make
the difference.

> However I still get errors from r.watershed
> and it seems related to the segment file:
>
> GRASS 6.4.1 (ML):~/grass/bin > r.watershed elevation=ML_elev
> stream=stream_total accumulation=accumulation_total threshold=10000 --o -m
> memory=2000
> SECTION 1 beginning: Initiating Variables. 5 sections total.
> WARNING: No such file or directory
> WARNING: dseg_open(): could not write segment file
> WARNING: Subprocess failed with exit code 136
>
> Can anybody tell me what is causing this (and how I could solve it)? In this
> case I was using a region of 19800x16200 pixels.

GRASS 6.4.2svn (patUTM32):~ > g.region rast=italy_dem20_final res=60 -p
projection: 1 (UTM)
zone:       32
datum:      wgs84
ellipsoid:  wgs84
north:      5220298.87460934
south:      3930058.87460934
west:       313280.88065731
east:       1328680.88065731
nsres:      60
ewres:      60.00118182
rows:       21504
cols:       16923
cells:      363912192

GRASS 6.4.2svn (patUTM32):~ > r.watershed italy_dem20_final
stream=stream_total accumulation=accumulation_total threshold=10000 -m
memory=2000
SECTION 1 beginning: Initiating Variables. 5 sections total.
SECTION 1b (of 5): Determining Offmap Flow.
 100%
SECTION 2: A * Search.
  46%
...

Looks fine!

Markus