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!
--j
--
Jonathan A. Greenberg, PhD
NRC Research Associate
NASA Ames Research Center
MS 242-4
Moffett Field, CA 94035-1000
Office: 650-604-5896
Cell: 415-794-5043
AIM: jgrn307
MSN: jgrn307@hotmail.com
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.
Ellen
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!--j
--
Jonathan A. Greenberg, PhD
NRC Research Associate
NASA Ames Research Center
MS 242-4
Moffett Field, CA 94035-1000
Office: 650-604-5896
Cell: 415-794-5043
AIM: jgrn307
MSN: jgrn307@hotmail.com