Hi list, I'm still struggling with i.atcorr as there are some steps that I'm not understanding very well. It concerns mainly how to treat the output.
1) I'm using input in radiance, following landsat transformation rules (Qmin, Qmax, etc). But from what I read in the manual, i.atcorr has an input range which, defaults to 0 to 255. As I see, this is basically transforming the radiance values back to DN. This now takes me to another question. My radiance transformation parameters are a bit messed up and I get negative radiances (I know this is wrong). So, is the range parameter in i.atcorr important? Would this mean that it's not necessary to use radiance values and that I could use the raw DNs? 2) Output is scaled from 0 to 255. I was under the impression that, to convert it back to reflectance, all I needed to do was divide by 255. But, because of that range parameter, I started thinking: If i.atcorr input radiance is scaled from 0-255 (similar to what DN values are) then, shouldn't the conversion from i.atcorr output to reflectance use the same transformation parameter as the DN-Radiance conversion formula? Cheers and hoping to get a better understanding of i.atcorr :) Daniel _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user