Nikos, Since my input raster is binary (0s and 1s), and I need to know how many of the neighboring cells are 1s, it's sufficient to simply compute the sum of the overall neighborhood. If I use r.mapcalc to mask out the rest of the raster, I can compute the sum of the entire map with r.sum. However, since I need to do this for hundreds of points, it seems silly to use such a cumbersome method that will require a lot of processing time.
Shaun On Mar 14, 2013, at 2:29 PM, Nikos Alexandris <[email protected]> wrote: > Shaun Langley wrote: >> I need to easily query a raster and return both the value of the cell and >> the aggregate value of the 8-cell neighborhood, given a set of point >> coordinates. I know I can easily do this with r.mapcalc, but that involves >> running the computation for the entire map even though I'm only interested >> in a very very small portion. Is there an easier way to do this or am I >> stuck with the long solution? > > What kind of an aggregation exactly? Maybe not straight-through, but > I think you will be "forced" to use G7: > > http://grass.osgeo.org/grass70/manuals/r.neighbors.html > > in a way like > > r.neighbors \ > input=QueriedRaster \ > selection=CellsOfInterest \ > output=AggregatedRaster \ > method=SomeMethod[,MoreMethods,EvenMoreMethods] \ > size=3 \ > title="Aggregated raster map" > > However, you say you need the "queried" cell-value as well. Maybe combine with > > http://grass.osgeo.org/grass70/manuals/r.what > > Best, Nikos _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
