[GRASS-user] selecting upstream river segments

[ivan marchesini]

Hi Markus and Silvia...
many thanks for your answer..

I have tried to use the solution proposed by Markus..
it works but it selects all the connencted stream... instead and I would
like to obtain only those upstream to the point I choose...
removing the others downstream

I have thougth this solution:
suppose I'm interested to the upstream part of a stream network starting
from a choosen segment of the stream network, so I can:
1) use v.to.db to find the downstream node of the selected segment
2) use v.edit to move this node (disconneting it from the downstream
segment)
3) get the new coordinates of the node
4) use the procedure suggested by markus (v.net.iso) starting from the
moved downstream node coordinates

What do you think about this solution?

many thanks 

Ivan






Il giorno mar, 22/04/2008 alle 10.08 +0200, Markus Neteler ha scritto:
> Hi Ivan,
> 
> please see
> http://www.nabble.com/Streams-extraction-from-streams-map-td10267212.html#a10306465
> 
> Markus
> 
> On Mon, Apr 21, 2008 at 8:58 AM, ivan marchesini <marchesini at unipg.it> wrote:
> > Dear Grass users,
> >
> >  I have a vector stream network map of a single basin (so only a stream
> >  "tree")...
> >
> >  each stream segment is correctly oriented downstream (the direction of
> >  each vector is from higher to lower elevation..)
> >
> >  I would like to select a random segment of the "tree" and automatically
> >  obtain only the upstream segments..
> >  i.e. I would like to obtain a new map containing only the upstream
> >  stream segments of the selected one... (that is the same of removing
> >  those downstream)
> >
> >  obviously I must implement this process into a shell script...
> >
> >  Could you suggest a simple way to solve this little problem?
> >  Can I use the direction of the vectors to solve this problem?
> >
> >  Many thanks
> >
> >  Ivan
> >
> >
> >
> >
> >  --
> >  Ti prego di cercare di non inviarmi files .dwg, .doc, .xls, .ppt.
> >  Preferisco formati liberi.
> >  Please try to avoid to send me .dwg, .doc, .xls, .ppt files.
> >  I prefer free formats.
> >  http://it.wikipedia.org/wiki/Formato_aperto
> >  http://en.wikipedia.org/wiki/Open_format
> >
> >  Ivan Marchesini
> >  Department of Civil and Environmental Engineering
> >  University of Perugia
> >  Via G. Duranti 93/a
> >  06125
> >  Perugia (Italy)
> >  Socio fondatore GFOSS "Geospatial Free and Open Source Software" http://www.gfoss.it
> >  e-mail: marchesini at unipg.it
> >         ivan.marchesini at gmail.com
> >  tel: +39(0)755853760
> >  fax (university): +39(0)755853756
> >  fax (home): +39(0)5782830887
> >  jabber: geoivan73 at jabber.org
> >
> >  _______________________________________________
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> >  grass-user at lists.osgeo.org
> >  http://lists.osgeo.org/mailman/listinfo/grass-user
> >
> 
> 
> 
-- 
Ti prego di cercare di non inviarmi files .dwg, .doc, .xls, .ppt.
Preferisco formati liberi.
Please try to avoid to send me .dwg, .doc, .xls, .ppt files.
I prefer free formats.
http://it.wikipedia.org/wiki/Formato_aperto
http://en.wikipedia.org/wiki/Open_format

Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a 
06125
Perugia (Italy)
Socio fondatore GFOSS "Geospatial Free and Open Source Software" http://www.gfoss.it
e-mail: marchesini at unipg.it
        ivan.marchesini at gmail.com
tel: +39(0)755853760
fax (university): +39(0)755853756
fax (home): +39(0)5782830887
jabber: geoivan73 at jabber.org