Hi Anders,
I think that this GRASS script (v.costdist.mat) that I did a couple of
years ago may fit.
You can get it from
http://www.geeitema.org/guenmap/index.jsp?opcion=resultados&idioma=en.
v.costdist.mat determines de cumulative cost of moving between each pair
of points from two given maps over a (single) cost surface.
The results are stored in the attribute table of the second set of
points (hence, you get a matrix of values).
You can only feed a single cost surface (friction map) at a time, so you
should make a script that loops over your set of friction maps.
Hope it helps.
ƒacu.-
On 25/08/10 15:52, Anders Gonçalves da Silva wrote:
Hello all.
I have a set of samples in a landscape. I want to create different friction
maps based on landscape features (i.e., presence/absence of roads, vegetation
type, etc.) to understand animal movement between habitat patches. I have used
v.distance to calculate the pairwise distance among the samples (which I assume
is the Euclidean distance). But, I would like to incorporate other features.
I have a dem, a vector map with points, and a vector map with vegetation types
and other land use types all in one mapset.
I tried to use r.walk to calculate the distance among the sample points based
solely on the topography by creating a friction map with all cells =1:
r.walk elevation=dem friction=area1 out=null.cost start_points=points
stop_points=points #similarly to what v.distance does, ie, the start points are
the same as the end points.
Computations proceed to the end, but when I try to visualise the results,
nothing appears on the d.mon.
Ideally, I would end up with different matrices of pairwise distances for each
different friction map, which represent different hypotheses about how the
animals interact with the landscape.
I am not sure what I am doing wrong, or even if this is the most efficient way
of approaching this problem. Any assistance would be appreciated.
Thank you.
Anders._______________________________________________
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