Problem with h.flowdirections

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Problem with h.flowdirections

Bis Nulama
I am having a problem with a NASA-strm dem that I already depitted. When I try to calculate the flowdirections I get this in the console:

Working on h.flow
Reading map PIT
Reading raster map: depit.asc
Finished.
Initialize boundaries...
Initialize internal pointers...
Set positive slope directions...
Now resolve flats...
-1
ograss warning: ignoring null value passed.

What does this mean?

Laura

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Re: Problem with h.flowdirections

Andrea Antonello
Hi Laura,

> I am having a problem with a NASA-strm dem that I already depitted. When I
> try to calculate the flowdirections I get this in the console:
>
> Working on h.flow
> Reading map PIT
> Reading raster map: depit.asc
> Finished.
> Initialize boundaries...
> Initialize internal pointers...
> Set positive slope directions...
> Now resolve flats...
> -1
> ograss warning: ignoring null value passed.
>
> What does this mean?

in the bugtracker we have a report that says: make flowdirection
errors more verbose :)

Usually this error occurs when the resolution is changed between the
creation of pit and flow.
Can that be?

Ciao
Andrea




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Re: Problem with h.flowdirections

Silvia Franceschi-2
Hi Laura,
are you using a metric projection and a square grid for your DTM?

Horton machine only works, for now, with metric projection and square resolution, same resolution north-south and east-west.

Let us know some other details about your data,

Silvia


On Tue, Jun 9, 2009 at 8:09 PM, andrea antonello <[hidden email]> wrote:
Hi Laura,

> I am having a problem with a NASA-strm dem that I already depitted. When I
> try to calculate the flowdirections I get this in the console:
>
> Working on h.flow
> Reading map PIT
> Reading raster map: depit.asc
> Finished.
> Initialize boundaries...
> Initialize internal pointers...
> Set positive slope directions...
> Now resolve flats...
> -1
> ograss warning: ignoring null value passed.
>
> What does this mean?

in the bugtracker we have a report that says: make flowdirection
errors more verbose :)

Usually this error occurs when the resolution is changed between the
creation of pit and flow.
Can that be?

Ciao
Andrea




>
> Laura
> ________________________________
> Personalizza Messenger 2009. Scegli la grafica che ti rappresenta meglio!
> _______________________________________________
> JGrass-users mailing list
> [hidden email]
> https://dev.fsc.bz.it/cgi-bin/mailman/listinfo/jgrass-users
>
>
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Re: Problem with h.flowdirections

Bis Nulama
In reply to this post by Bis Nulama



Dear Antonello and Silvia,

I did not change the resolution between the creation of the depitted dem and the flowdirectins one...

Actually my NASA DEM has a geographic projection, so the cellsize is not in metres but in degrees...

NCOLS 1589
NROWS 957
XLLCORNER 6.528750
YLLCORNER 45.319584
CELLSIZE 0.000833
NODATA_VALUE -9999.000000

So I should change projection! (Big deal!)



Thanks

Laura

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