On Tue, May 17, 2011 at 10:34 PM, Elena Mezzini <[email protected]> wrote: > > On Tue, May 17, 2011 at 10:08 PM, Elena Mezzini > <[email protected]> wrote: >> >> On Tue, May 17, 2011 at 9:22 PM, Elena Mezzini >> <[email protected]> wrote: >>> Hi all, >>> I'm once again in trouble with i.atcorr in GRASS6.5.svn. >>> I notice that my output reflectance images are strange: there are some >>> areas >>> that are really bright and other that are really dark. Both seem to match >>> with my DEM raster. >>> Could there be problems with negative values in DEM?? I'm in a coastal >>> area >>> and there are some real altitude negative values. >> >> i.atcorr (the 6S code it is using to be exact) should treat negative >> elevation values as elevation = 0. It is debatable if this is correct, >> but in theory i.atcorr should behave accordingly. Actually, I am not >> sure about it's behaviour for negative elevation values... >> >> You could set all negative elevation values to zero, >> >> >> Ok, how can I do it? >> > replace my_elevation with the name of your elevation map: > > g.region rast=my_elevation > r.mapcalc "elevation_positive = if(my_elevation < 0, 0, <my_elevation>)" > > > > g.region rast=dem_sross_srtm > r.mapcalc "dem_sross_srtm_pos = if(dem_sross_srtm < 0, 0, <dem_sross_srtm>)" > > Syntax error! > As you know I'm not a programmer... where is the error?
remove the <> (actually I forgot to remove them in the template...): r.mapcalc "dem_sross_srtm_pos = if(dem_sross_srtm < 0, 0, dem_sross_srtm)" _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
