Hi all!
I am having terrible problems with r.watersheds. In short: I can't
get it to work! I am trying to estimate the confluence of present-day
basins if the sea level was lower. I'm using the ETOPO2 DEM
restricted to Panamá. The program seems to run, until it reaches step
6 (``closing maps''). Then it goes on forever---I've let it run for
days, and always had to abort it. The machine is not so fast: PIII
running Linux.
Is there any way to fix this? Is there any parameter which value
would cause this? How long is the program supposed to run? Can it
really be ``closing maps'' for 10 days?
TIA.
-Gustavo
--
``La imagination au povoir.''
Gustavo Alcides Concheiro Pérez <gacp@d-konstruktors.org>
On Mon, Feb 03, 2003 at 09:32:19PM -0500, Gustavo Alcides Concheiro Perez wrote:
Hi all!
I am having terrible problems with r.watersheds. In short: I can't
get it to work! I am trying to estimate the confluence of present-day
basins if the sea level was lower. I'm using the ETOPO2 DEM
restricted to Panamá. The program seems to run, until it reaches step
6 (``closing maps''). Then it goes on forever---I've let it run for
days, and always had to abort it. The machine is not so fast: PIII
running Linux.
Is there any way to fix this? Is there any parameter which value
would cause this? How long is the program supposed to run? Can it
really be ``closing maps'' for 10 days?
Yes, that is possible. r.watershed does not work well with large
data sets.
There is a replacement in the CVS: r.terraflow.
http://www.cs.duke.edu/geo*/terraflow/
You either have to compile yourself or wait for 5.0.2 (AFAIK it will
be included) [1].
Best regards
Markus Neteler
[1] There is an inofficial GNU/Linux binary version of the recent CVS HEAD:
http://grass.itc.it/pipermail/grass5/2003-January/004647.html
including r.terraflow (FLOAT version) and r.terraflow.short (Integer
version).
Note that this compilation is inofficial and may not be 100% identical
to the upcoming 5.0.2 release. If you feel confused, please ignore
this suggestion 
On Tue, Feb 04, 2003 at 11:53:16AM +0100, Markus Neteler wrote:
On Mon, Feb 03, 2003 at 09:32:19PM -0500, Gustavo Alcides Concheiro Perez wrote:
[...]
[1] There is an inofficial GNU/Linux binary version of the recent CVS HEAD:
http://grass.itc.it/pipermail/grass5/2003-January/004647.html
including r.terraflow (FLOAT version) and r.terraflow.short (Integer
version).
Note that this compilation is inofficial and may not be 100% identical
to the upcoming 5.0.2 release. If you feel confused, please ignore
this suggestion
Due to bugs reported today related to recent changes I have removed
these precompiled linux binaries of 5.0.2pre1.
Sorry for any inconvenience, we recommend to wait for the official
5.0.2 release. These new bugs are currently under revision.
Kind regards
Markus Neteler
I am having terrible problems with r.watersheds. In short: I can't
get it to work! I am trying to estimate the confluence of present-day
basins if the sea level was lower.
Try loading the DEM into NVIZ, Panel-> Surfaces, New: Constant, 0.0
Transpenency: new constant 128
Color: new constant [blue]
then 'draw current'.
You should have a semi-transparent blue surface at 0 elevation representing sea level.
Raise and lower sea level with the 'Position' button (eg z=-30) until the basins separate.
It isn't exactly scientific, but it works pretty well and looks good too.
see http://bambi.otago.ac.nz/hamish/pics/sill_iceage_115m.jpg for an example.
Hamish
