On Mon, Jun 23, 2008 at 4:02 AM, Colin Nielsen <[EMAIL PROTECTED]> wrote: > I realized that the r.drain function does not adequately create a > least-cost path on a cumulative cost surface. This is because there is > no check within the r.drain function to ensure that the "steepest" > downhill change in cost value is actually the same as the direction of > cost accumulation during the cost calculation. This means that there > is a disconnect between the movement direction in r.walk and the path > created by r.drain. > > To fix this I have added the creation of a movement direction output > raster to the r.walk code. This way the original movement directions > will be preserved and the true least-cost path may be found using > another module which traces the directional surface backwards. > > My question is, should the direction tracing module be: > a) incorporated into r.drain with a flag specifying a cost surface > rather than dem input, and an additional direction input > b) write a new, separate module called r.costpath > > More modules or more complex modules? > > Thanks for the advice, > -Colin
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 Cheers, Dylan _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
