[GRASS-user] Automatic extraction of valley features

[Vaclav Petras]

Hi,

On Thu, Nov 12, 2015 at 5:09 AM, Jean-Roc Morreale <jr.morreale at enoreth.net>
wrote:

> I would like to know how to extract a valley feature from a DEM as a
> polygon


The classic way would be to use r.param.scale with method=feature, but I
would recommend using r.geomorphon by Stepinski and Jasiewicz (2011, 2013).

Both modules will give you a raster map. You can use r.to.vect to get
vector polygons. To get just the valley use either raster algebra
(r.mapcalc) on the raster map or v.extract on the vector map.

Note that r.geomorphon module is in GRASS Addons repository, so use e.g.,
g.extension r.geomorphon to get it.

Vaclav

https://grass.osgeo.org/grass70/manuals/r.param.scale.html
https://grass.osgeo.org/grass70/manuals/addons/r.geomorphon.html
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