Hi Jose, I haven't tryed i.landsat.toar addon but from what I read in the wiki (http://grass.osgeo.org/wiki/Atmospheric_correction) I could either use i.landsat.toar or a DN - Radiance conversion formula that is given...
Will try to recalculate the images, I might have done something wrong Daniel 2010/8/2 José Miguel Barrios <[email protected]>: > Hey Daniel > > I think the input map to be given in i.atcorr should not be the DN. > Conversion to radiance or reflectance should be done before implementing the > 6s algorithm. Have you tried i.landsat.toar to obtain radiance values? > > Success! > > JM > > > 2010/8/2 Daniel Victoria <[email protected]> >> >> Hi all, >> >> I'm trying to estimate albedo from landsat5 images but I'm getting >> very strange result. Water bodies, for instance, are giving me an >> albedo of 0.15 to 0.17, unusualy high. >> Here is the procedure I'm doing >> >> 1) Convert TM images from grey level to radiance using the Lmax / Lmin >> formula (parameters used given bellow [1]) >> 2) Apply 6S atmospheric correction, using standard tropical >> atmosphere, continental aerosol mode >> 3) Calculate shorwave albedo using Liang (2000) formula (based on >> bands 1; 3; 4; 5 and 7) >> >> Since the albedo of water areas is comming out too high, I'm guessing >> I messed up the i.atcorr procedure. I don't quite understand what >> should be the input image (DN or Radiances?) and what is the output >> image (reflectance scaled to 255?) >> >> Thanks >> Daniel >> >> >> [1] >> Band LMIN LMAX >> 1 -1,52 193 >> 2 -2,84 365 >> 3 -1,17 264 >> 4 -1,51 221 >> 5 -0,37 30,2 >> 7 -0,15 16,5 >> _______________________________________________ >> grass-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/grass-user > > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
