i am working on grass gis. how to use grass gis for liss4 of IRS-P6.I have to do atmospheric correction for hilly terrain data.i would like to use grass's i.atcorr. may i know the dependencies and how to customize it for my problem.will liss4 data directly used in that module?or only it is limited to specific sensors. i would also like to inform that i have compiled OTB4.0 but the code assumes that surface as Lambert which not suitable to my study. hence i want to use grass gis for it. will grass also has same assumption of lambertian surface? please suggest me.