Thomas Becker wrote: > Hi, > > I know it is pretty standard to subtract to maps from each other and I do > have the command for r.mapcalc, but it is not doing what I expect. > > I have a landcover map and a map wit buildings. Both are raster maps. Now I > want to get rid of the areas in the landcover map that are covered by > buildings. To get this done I wrote: > > r.mapcalc "newmap = landcover - buildings" > r.mapcalc "newmap = if (isnull(buildings), landcover, null())"
may do the trick, assuming that the buildings map has nodata where there are no buildings. The newmap would have nodata where there are buildings otherwise landcover. Markus M > The outcome is a map showing only the buildings and no landcover. It also > doesn't matter if I change the order in the equation, the result is the same: > Only buildings are delivered. > > Can you help me out with this? > > Thanks, > Thomas > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
