Hi,
After a couple of days I got a successful output from r.watershed.
Well, almost successful. Some basins looks very weird, as you can see
in the attached file. Is it because I did not mask out the null cells
on the dem map (white area on dem30.jpg)?
Thanks
Daniel
On Jan 7, 2008 7:40 PM, Daniel Victoria <daniel.victoria@gmail.com> wrote:
Hi,
After a couple of days I got a successful output from r.watershed.
Well, almost successful. Some basins looks very weird, as you can see
in the attached file. Is it because I did not mask out the null cells
on the dem map (white area on dem30.jpg)?
Right. No data needs to be no data...
Markus
But the no data on the dem was treated by grass as nodata (when using
d.what.rast). Why mask out what is already nodata?
On Jan 8, 2008 1:35 PM, Markus Neteler <neteler@osgeo.org> wrote:
On Jan 7, 2008 7:40 PM, Daniel Victoria <daniel.victoria@gmail.com> wrote:
> Hi,
>
> After a couple of days I got a successful output from r.watershed.
> Well, almost successful. Some basins looks very weird, as you can see
> in the attached file. Is it because I did not mask out the null cells
> on the dem map (white area on dem30.jpg)?Right. No data needs to be no data...
Markus
I just noticed that there are some small islands of the coast of South
America that are represented in the DEM that I though where not there.
Could that mess up the basin delineation over the continent? Would
that explain why the coastal basins shoot out to the ocean (Nodata
region in the DEM)?
Thanks
Daniel
On Jan 7, 2008 4:40 PM, Daniel Victoria <daniel.victoria@gmail.com> wrote:
Hi,
After a couple of days I got a successful output from r.watershed.
Well, almost successful. Some basins looks very weird, as you can see
in the attached file. Is it because I did not mask out the null cells
on the dem map (white area on dem30.jpg)?Thanks
Daniel
Investigating further I don't think the islands of the cost have much
to do with the problem. You can see in the attached jpg how the
streams generated do not go over one of the islands (top left of the
image - Fernando de Noronha, great SCUBA place)
Also, some streams are generated along the cost because the basin of
that region is extending into the ocean...
Any clues as to what is going on? Has anyone else seen this? I'm using
Grass 6.2.2 from the Debian repos
Cheers
Daniel
On Jan 9, 2008 10:12 AM, Daniel Victoria <daniel.victoria@gmail.com> wrote:
I just noticed that there are some small islands of the coast of South
America that are represented in the DEM that I though where not there.
Could that mess up the basin delineation over the continent? Would
that explain why the coastal basins shoot out to the ocean (Nodata
region in the DEM)?Thanks
DanielOn Jan 7, 2008 4:40 PM, Daniel Victoria <daniel.victoria@gmail.com> wrote:
>> Hi,
>
> After a couple of days I got a successful output from r.watershed.
> Well, almost successful. Some basins looks very weird, as you can see
> in the attached file. Is it because I did not mask out the null cells
> on the dem map (white area on dem30.jpg)?
>
> Thanks
> Daniel
>
