> 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? > > Nikos Alexandris wrote: >> 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 > > Maybe combine all this with a MASK? i.e., create buffer(s) around your > coordinates of interest, use r.what and r.neighbors then?
Ah! I think I see what you're saying. If I create a new raster where all cells are replaced by the sum of their neighbors, then I can run queries for each point without having to recompute the neighborhood. This might work. Is this what you had in mind? > (@MMetz -- maybe of your interest?) > And, at this point comes the idea: why not let r.neighbors, when a > "selection=RasterMap" is defined, return in an extra raster map the > one-central > queried cell? > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
