Maybe something like this... For each catchment you run r.info -r to get the highest and lowest value of the DEM (use a MASK for the catchment and r.info -r DEM).
Then, with r.mapcalc you select the highest and lowest areas that you obtained with r.info. After that you can vectorize the areas selected and do v.db.update to get coordinates. It would be nice to put this all into a script if you have too many catchments. One problem would be that you might not get a single pixel for the high and low parts of the basin. It could be a small area... Another thing. v.rast.stats can give you the max and min value for a DEM for every catchment. It just wont give you the coordinates - not that I know of... Good luck Daniel On Jan 30, 2008 5:03 AM, Dr. Manuel Seeger <[EMAIL PROTECTED]> wrote: > Thanks Richard, > but elevation data is on a raster map. > The idea I had was to generate point vector files with the highest and > lowest point and then generate the colums with y and y coordinates... > but it seems to me like a complicated way and I was wondering if there > is a possibility to do that with r.mapcalc.... I think the functions are > ther, but how combining? > > Perhaps someone knows a way? > > Thanks > MAnuel > > Richard Chirgwin schrieb: > > > [EMAIL PROTECTED] wrote: > >> Send grass-user mailing list submissions to > >> [email protected] > >> > >> To subscribe or unsubscribe via the World Wide Web, visit > >> http://lists.osgeo.org/mailman/listinfo/grass-user > >> or, via email, send a message with subject or body 'help' to > >> [EMAIL PROTECTED] > >> > >> You can reach the person managing the list at > >> [EMAIL PROTECTED] > >> > >> When replying, please edit your Subject line so it is more specific > >> than "Re: Contents of grass-user digest..." > >> > >> > >> Today's Topics: > >> > >> 1. highest and lowest point in catchment (Dr. Manuel Seeger) > >> 2. SHELL Variable problem: Workaround (Peter L?we) > >> 3. Re: SHELL variable not set (Martin Wegmann) > >> 4. Re: SHELL variable not set (Glynn Clements) > >> 5. Re: SHELL variable not set (Hamish) > >> 6. Re: SHELL variable not set (Markus Neteler) > >> 7. Re: Building wxgrass vdigit (Martin Landa) > >> 8. segment_format error with r.watershed (Wes Kent) > >> 9. union features of vector (Alfredo Alessandrini) > >> 10. Re: Snap across layers (Martin Landa) > >> > >> > >> ---------------------------------------------------------------------- > >> > >> Message: 1 > >> Date: Tue, 29 Jan 2008 10:01:20 +0100 > >> From: "Dr. Manuel Seeger" <[EMAIL PROTECTED]> > >> Subject: [GRASS-user] highest and lowest point in catchment > >> To: GRASSLIST <[email protected]> > >> Message-ID: <[EMAIL PROTECTED]> > >> Content-Type: text/plain; charset=ISO-8859-15; format=flowed > >> > >> Hello all, > >> I hope the questions does not seem too simple, but I have now no real > >> good idea how to solve this simple problem: > >> > >> I need to find the highest and the lowest point within catchments > >> WITH their coordinates (and to get the information about altitude and > >> coordinates, of course) > >> > >> thanks for hints! > >> > >> manuel > >> > >> > > Manuel - hope I'm not being silly here, but I'd consider just using an > > SQL select directly to the data store. > > > > Select max( <altitude column> ), <latitude column>, <longitude > > column>, <any other column you want> from <table> where <boundary > > conditions of catchment> > > Select min( <altitude column> ), <latitude column>, <longitude column> > > <any other column you want> from <table> <boundary conditions of > > catchment> > > > > If you have to, you could extract only the catchment to a separate > > vector, so that you don't need to fool around with complex boundary > > conditions. > > > > But I'm sure that a genuine Grass expert will have a simpler solution > > than this ... > > > > Cheers, > > Richard > > _______________________________________________ > > grass-user mailing list > > [email protected] > > http://lists.osgeo.org/mailman/listinfo/grass-user > > > > > -- > > _______________________________________________________________________ > Dr. Manuel Seeger > Wiss. Assistent Scientific Assistant > Physische Geographie Dpt. of Physical Geography > FB VI - Geographie/Geowissenschaften Geography/Geosciences > Universität Trier University of Trier > D - 54286 Trier > Tel.: +49-651-201 4557 > Fax: +49-651-201 3976 > Web: http://www-neu.uni-trier.de/index.php?id=9607 > > _______________________________________________ > > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
