Dylan:
> > Interesting post Colin. Can you comment on the differences between
> > r.drain and r.walk in this example [1], in light of your findings?
> > 1. http://casoilresource.lawr.ucdavis.edu/drupal/node/544
teaching r.walk to follow ridgelines when possible would be cool for back
country stuff. Perhaps r.mapcalc multiply the slope-cost input map with a
r.param.scale feature map that likes ridges and saddles but doesn't like
gullies and pits? treelines too.
Also set cost map to NULL if slope > x so it doesn't have you crossing
cumulatively short but physically challenging 20m cliffs.
Colin:
> Excellently documented example by the way.
>
> The path is probably quite similar but the point is that there is
> currently no way to ensure that the r.drain path conforms to the
> same path as the optimal path of cost accumulation (calculated
> by r.walk or r.cost).
AFAIR r.drain just blindly climbs to the next up/downhill D8 cell, in a loop,
until it can climb/drop no more. thus it is not "least" cost at all, just one
valid solution? (??)
Hamish
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