[GRASS-user] Shortest path for a new road

[Hamish]

> Wolf Bergenheim wrote:
> > I need to create a plan for a new road from a known source point, to
> > a known destination area. I have a grid of elevation and land use
> > for the region.

Dylan Beaudette wrote:
> The usual approach in GRASS for this type of problem is:
> 
> 1. define cost surface (slope is commonly used) but a distance map
> would work  as well (r.mapcalc "dist = 1")
> 
> 2. create cumulative cost map (r.cost) along with the cost surface
> from step 1
> 
> 3. simulate a drop of water 'draining' from some destination to the
> point of  least cost (your starting point) (r.drain)
> 
> 4. use r.to.vect to vectorize the output from r.drain.
> 
> rather verbose example here:
> http://casoilresource.lawr.ucdavis.edu/drupal/node/244


see also the "GRASS Seeds" Leicester raster tutorial for an example.
  http://grass.itc.it/gdp/tutorials.php


Hamish