2011/5/24 Markus Neteler <[email protected]> > On Tue, May 17, 2011 at 10:57 PM, Elena Mezzini <[email protected]> > wrote: > > Elena Mezzini wrote: > >> Markus Metz-2 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. > ... > ... > >> g.region rast=dem_sross_srtm > >> r.mapcalc "dem_sross_srtm_pos = if(dem_sross_srtm < 0, 0, > dem_sross_srtm)" > ... > > No differences between negative and positive values... > > What do you mean precisely? > > I mean that i.atcorr automatically considers negative values equal to 0. So the results of i.atcorr with negative values or with negative values made equal to zero are the same. So I still have problem with all the bands of landsat probably due to DEM.
Elena
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