Dylan Beaudette wrote: > >> >> Does anyone know how to do Thiessen Polygons in GRASS? > >> >> > >> >> I need to use them around various types of megalithic tomb > >> >> sites that are in point vector files. > >> > > >> > v.voronoi > >> > > >> > > >> > there is some replacement test code to look at in grass-addons as well: > >> > http://trac.osgeo.org/grass/browser/grass-addons/vector/voronoi > >> > >> While we are on this topic, is there a way to get a weigthed voronoi > >> diagram using grass ? > >> > >> The ability to rank a point to tune the area's influence would be great, > >> for that purpose I've been using an arcgis'extension* but with grass it > >> is not possible**. Is there a way to get a similar result ? > >> > >> *http://www.geog.unt.edu/~pdong/software.htm > >> **http://osdir.com/ml/gis.grass.user/2004-04/msg00036.html > >> > >> Regards, > >> MORREALE Jean Roc > > Now that I have read about 'weighted voronoi diagrams', I wonder if a > combination of r.cost + r.mapcalc would solve this problem. Something > along those lines is demonstrated here: > > http://casoilresource.lawr.ucdavis.edu/drupal/node/288 > > This example isn't quite what is requested, although using r.cost with > start=point_i, and stop=neighbor_points (derived from v.delaunay / > v.distance?) may work. It would then be a little more work to convert > the weighted-distance rasters into polygons, and link back to the > original attribute tables... but (hopefully) not outside the realm of > possibility via a script.
The problem with using r.cost is that you would need to know the cost for each cell before you have created the polygons. I think that the simplest accurate approach would be to modify r.grow.distance. -- Glynn Clements <gl...@gclements.plus.com> _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user