leonidas wrote: > Thank you for your answers! > I did g.region rast=aster_dem_ggrs and then I run again r.slope.aspect but > the problem still remains. > > Here is the whole process. > 1. I download the tiles from http://www.gdem.aster.ersdac.or.jp/search.jsp > 2. Merge them: *gdalwarp ASTG* mosaic.tif* > 3. Reproject the raster to greek grid: *gdalwarp -s_srs EPSG:4326 -t_srs > EPSG:2100 mosaic.tif dem_temp.tif*
This is the problem. Resampling introduces artifacts which affect the gradient calculation. Ideally, you should calculate the slope and aspect on the original data, then re-project the result. Failing that, either use the -r switch to select a more suitable resampling method (such as cubic, cubicspline or lanczos) or filter the data with e.g. r.mfilter or r.neighbors prior to running r.slope.aspect. -- Glynn Clements <[email protected]> _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
