Hi everyone I have one question how can calculate Nitrogen index from ASTER data. Also I looked the help of ENVI but there is different between wavelength of Nitrogen equation and ASTER wavelength. I want to use vegetation indices for landscape. Please tell me how can make Nitrogen equation in ENVI? If who help me about this problem I will be appreciated. If another data is necessary please tell me. Normalized Difference Nitrogen Index NDNI=log(1/p1510)-log(1/p1680)/ log(1/p1510)+log(1/p1680) Sincerely Yours, Hadi Fadaei