[GRASS-user] Extraction 3D vectors ridges/Thalweg from raster DEM ?

[Micha Silver]

On 12/12/2013 15:47, image wrote:
> Dear all,
>
>  From my Raster DEM, i would like extract Thalweg and Drainage divide
> (ridges) 's 3D vectors.
>
> According to you, is it possible to do that with grass?
Certainly

First use the r.watershed module to create streams and basins (rasters) 
from your DEM. Now do r.thin and r.to.vect on the streams raster to get 
a vector layer. Finally v.drape on that vector layer using the DEM to 
get a 3D vector result.

For the drainage divides, use r.to.vect on the basins raster to get an 
area vector of the basins. Then you can use v.extract type=boundary to 
get just the boundary lines from the basins. And then, as above, v.drape 
to create the 3D vector of watershed boundaries.
> In advance, Thank you.
>
> Regards.
>
>
>
> --
> View this message in context: http://osgeo-org.1560.x6.nabble.com/Extraction-3D-vectors-ridges-Thalweg-from-raster-DEM-tp5093957.html
> Sent from the Grass - Users mailing list archive at Nabble.com.
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>
> This mail was received via Mail-SeCure System.
>
>


-- 
Micha Silver
GIS Consulting
052-3665918
http://www.surfaces.co.il