[GRASS-user] cost analysis

GRASS GRASS user
1

Hello,
I would like to perform a nature connectivity analysis, generation of paths connecting natural areas, taking into account several cost grids (eg: land-use, level of protection, kind of soil,vegetation,etc).

I have read that the r.cost is an option (http://grass.itc.it/grass61/manuals/html61_user/r.cost.html) but but) I would need to use more than one cost grid. The option that r.walk (http://grass.itc.it/grass61/manuals/html61_user/r.walk.html) offers is not so suitable for me as the elevation in my study is not so relevant (it is quite a flat area).

Does anyone knows if with the r.cost it is possible to integrate more than one grid for the least cost computation? or if for r.walk the elevation grid can be another grid(s) instead of the elevation one?.

Of course the option of computing, for several overlaying grids, the per cel cost in the r.mapcalc before hand is always possible.But I was wondering if there is an application available that performs such a multigrid least-cost calculation automatically.

The option that r.drain (http://grass.itc.it/grass61/manuals/html61_user/r.drain.html) gives is also very interesting for my study. The generation of the least cost path is a very good way to select connectivity areas between natural patches. But again r.drain operates taking into account an elevation data set and a cost grid one. Does it exists a module as r.drain taking into account several cost grids, not especially the elevation one, for calculating a least-cost path?

Anyother option that I did not mention here is more than welcomed!

Thanks you very much for your help.

Regards,
María Piquer

María Piquer Rodríguez
Mozartstr, 58
53115 Bonn
Germany

LLama Gratis a cualquier PC del Mundo.
Llamadas a fijos y móviles desde 1 céntimo por minuto.
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2

Maria,

A simple approach would be to construct a composite "travel friction" map. I
have done this before (example to follow) using a slope map, wooded areas
map, and water feature map. This was for predicting least cost trails through
a wilderness area minimizing:
-travel across high slope gradient
-travel through water features

and maximizing:
-travel through wooded areas

The details can be found here:
http://casoilresource.lawr.ucdavis.edu/drupal/node/244

The general concept is:
create a slope map, as as starting "friction" surface.
encode other information into this map via r.mapcalc
run r.cost
run r.drain

Cheers,

Dylan

On Thursday 29 June 2006 02:47, María Piquer Rodríguez wrote:

Hello,
  I would like to perform a nature connectivity analysis, generation of
paths connecting natural areas, taking into account several cost grids (eg:
land-use, level of protection, kind of soil,vegetation,etc).

  I have read that the r.cost is an option
(http://grass.itc.it/grass61/manuals/html61_user/r.cost.html) but I would
need to use more than one cost grid. The option that r.walk
(http://grass.itc.it/grass61/manuals/html61_user/r.walk.html) offers is not
so suitable for me as the elevation in my study is not so relevant (it is
quite a flat area).

  Does anyone knows if with the r.cost it is possible to integrate more
than one grid for the least cost computation? or if for r.walk the
elevation grid can be another grid(s) instead of the elevation one?.

  Of course the option of computing, for several overlaying grids, the per
cel cost in the r.mapcalc before hand is always possible.But I was
wondering if there is an application available that performs such a
multigrid least-cost calculation automatically.

  The option that r.drain
(http://grass.itc.it/grass61/manuals/html61_user/r.drain.html) gives is
also very interesting for my study. The generation of the least cost path
is a very good way to select connectivity areas between natural patches.
But again r.drain operates taking into account an elevation data set and a
cost grid one. Does it exists a module as r.drain taking into account
several cost grids, not especially the elevation one, for calculating a
least-cost path?

  Anyother option that I did not mention here is more than welcomed!

  Thanks you very much for your help.

  Regards,
  María Piquer

    María Piquer Rodríguez
Mozartstr, 58
  53115 Bonn
  Germany

---------------------------------

LLama Gratis a cualquier PC del Mundo.
Llamadas a fijos y móviles desde 1 céntimo por minuto.
http://es.voice.yahoo.com

--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341