Hello Markus. Thanks for your answers > As far as I saw, there are no GRASS functions to perform Radiometric
> > Correction. > There is: i.atcorr. > Regarding i.atcorr I thought that the only thing i.atcorr perfoms is the atmospheric correction, I mean conversion from TOA (top-of-atmosphere) to BOA (Bottom-of-atmosphere). But how about the correction of illumination variations and instrument calibration? 6S also includes this? (by the way, at i.atcorr manual one of the links (INPE) is dead) I.atcorr is equal to 6S models provided by Maryland Univ group? Regarding Geometrical conditions: - Is it possible to addapt this to a SPOT image or UK-DMC image? I mean there is a list of pre-defined bands and those satellites, among others, are not there. But it is possible to apply this model to others satellite images? Yes, please see > http://grass.osgeo.org/wiki/Atmospheric_correction > > Regarding The estimation the overpass time from the sun position: Is this retrieved information useful for the i.atcorr process right ? and is this information placed automatically in the ICND file? Thank you for your help Markus Best regards Nikos
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