[GRASSLIST:7981] Re: Calculating "costdistance" using a DEM (aka
Ellen De Beuckeleer
ellen.debeuckeleer at incgeo.be
Fri Aug 19 02:43:22 EDT 2005
To calculate the shortest distance between two points first create a
cost surface. this can be done via the user interface: Raster->Terrain
Analysis->cost surface, which calls r.cost. You need to give the raster
map which contains the costs. This can be your DEM, (but you can also
use the slope (Raster->Terrain Analysis->slope and aspect =
r.slope.aspect) to create slopes based on your DEM.) You also need to
give the coordinates of your starting point.
After creating the cost surface call r.drain (Raster->Terrain Analysis->
Least cost route or flow). As parameters you have to provide the end
point of your route. You can choose between 3 flags: -c Copy input
cell values on output, -a Accumulate input values along the path,
-n Count cell numbers along the path.
I think, this should do it.
Jonathan Greenberg wrote:
>How do I go about calculating the shortest distance between two points given
>a DEM? I think this is called costdistance in ARC, but is there an
>equivalent for GRASS? Thanks!
>Jonathan A. Greenberg, PhD
>NRC Research Associate
>NASA Ames Research Center
>Moffett Field, CA 94035-1000
>MSN: jgrn307 at hotmail.com
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