stephen sefick wrote:
Well, I am not sure what I am going to do. I would look at the code,
but I am not adept at C. Also, I don't know if I understand the
algorithm, but I think if the topology were complete then it would
work OK. I think the 0 orders are unconnected streams- danglers.
Should not happen unless you specified real depressions in r.watershed.
How did you extract streams?
This makes sense because they are neither a tributary nor a main stem.
The topology is the problem,
What exactly is wrong with topology? The existence of these dangles?
Markus M
and I can't figure out how to correct
this.
thanks
Stephen Sefick
On Tue, Jul 21, 2009 at 12:34 PM, Markus
Metz<markus.metz.gisw...@googlemail.com> wrote:
Margherita Di Leo wrote:
I'm sorry but the procedure that I proposed does not produce good results.
In fact the ascii file produced by v.strahler has very strange orders, and
also many 0 (that does not have sense in strahler order!). I think the
problem is generated in finding the outlets
Outlet points are where stream is not null and drainage direction is
negative, e.g.
r.mapcalc "outlet_points = if(!isnull(streams) && drainage < 0, streams,
null())"
That would give you outlet points whose cell value is the stream segment
number leading to the outlet point.
and/or confluences.
All nodes of the stream vector, excluding outlet points?
Markus M
Waiting for the response of the List (please)..
margherita
Jarek Jasiewicz wrote:
Hi
maybe this will help:
http://gis.vsb.cz/GIS_Ostrava/GIS_Ova_2009/sbornik/Lists/Papers/060.pdf
it require another gis program but gives great results!
Jarek
Margherita Di Leo pisze:
Hi Stephen,
I actually am fighting against almost the same problem, so let's do it
together :)
I found that r.strahler.sh works well to delineate streams and correct
topology, (I use a treshold of 1km^2, it works well but don't ask me why :)
), but (in my little experience) does not work to order streams, so I must
run v.strahler after r.strahler.sh.
I know it's a very small hint but hope this helps.
Best
margherita
I have a low relief area in the costal plain of georgia that I am trying
to produce a topologically correct stream network. There are many breaks in
the flow accumulation grid and I would like to delineate the streams and
"correct" the topology after r.thin and r.to.vect have been preformed so
that I can then use v.strahler to order the streams. Thanks for any help and
I will provide and data that would be helpful. thanks,
-- Stephen Sefick Let's not spend our time and resources thinking about
things that are so little or so large that all they really do for us is puff
us up and make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals. -K. Mullis
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