Were you using ATREM with SIPS? I forget whether they worked together. At any rate, the modern tool that is similar to ATREM and works with ENVI is FLAASH. It is part of the ENVI Atmospheric Correction Module. That module also has a tool called QUAC, that gives good results with less parameters required at input (and also less user control). If you have field reflectance spectra, you may also be able to use the Empirical Line Calibration, which is available in the core ENVI product. - Peg Exelis VIS

Peg, Yes, I used ATREM with SIPS back in the mid-90s. My question was how to convert from Radiance to Reflectance without FLAASH or QUAC. I don't have field reflectance data, so I was going to use the modules that exist in ENVI, but see that I have to purchase the ENVI Atmospheric Correction Module. I'm in the process of getting a PO to do that, but am curious as to why would EXELIS not include a radiance to reflectance module standard with the software? Do people actually analyze data without converting it to reflectance? How can anyone compare laboratory reflectance data to field data without converting it to reflectance? Am I missing something? Thanks again, Joe

Hi Joe, Yes, you are right that you will need the Atmospheric Correction module unless you have field reflectance spectra that you can use with the empirical line calibration. Or unless you are satisfied with something quite simple and limited like a dark object subtraction. That's unlikely when working with AVIRIS data. I believe it is still true that most ENVI users are not working with spectrally high resolution data (like AVIRIS), and so the sophisticated model-based atmospheric corrections that FLAASH provides are not necessary for them. Actually, quite a lot of people never compare field/lab and image pixel spectra at all in ENVI, and do not require the atmospheric correction tools. - Peg Exelis VIS