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Last Post 04 Jun 2013 12:45 AM by  anon
QUAC with RapidEye
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anon



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04 Jun 2013 12:45 AM
    Hi there, I am trying to correct RapidEye imagery for atmospheric effects using QUAC function in ENVI. The output values I get are between 0 and 12000, however only about 0.05% of the values are above 10000. For surface reflectance, I would expect to get a value between 0 to 1 or 0 to some scaling factor such as 100. Just wanted to know if 10000 is the scaling factor used and if so why I get those values over 10000. Am I missing a step such as correcting for illumination variations, or is it because QUAC is more suitable for hyperspectral imagery? I don't have access to Flaash to compare the outputs, but should I consider using Flaash. Thanks

    MariM



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    04 Jun 2013 06:25 AM
    Quac does scale the output by 10000 just as FLAASH does. Some pixels can be poorly modeled and can result in values over 10000 or less than 0 in areas of very high or very low radiance. For Quac, be sure to exclude any background pixels using a mask for best results. If you have access to Quac then you have access to FLAASH as they are both unlocked with the same atmospheric correction module license. However, Quac is a much easier process to use and usually within +/-15% of the physical model of FLAASH.
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