Rich Shepard wrote: > > Run r.slope.aspect on the interpolated map, and check for grid-like > > artifacts. > > Glynn, > > Did this. Yes, there is a grid-like appearance to the resulting map. > > > How good is the underlying data? If it's noisy, it may need to be > > filtered before interpolating. > > How do I check for noisy data? I have all the basic information about the > source data and derived maps.
One trick is to create a filtered map with e.g. r.neighbors method=average or r.mfilter.fp, and subtracting the original map from the resulting map. This will help to highlight any artifacts introduced by processing of the source data. Any such processes should be performed at the map's native resolution, to ensure that artifacts aren't introduced by nearest-neighbour resampling. One thing which can introduce grid-like artifacts is nearest-neighbour resampling (including re-projection) at near-unity scale factors. -- Glynn Clements <gl...@gclements.plus.com> _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
