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Last Post 24 Aug 2009 10:17 AM by  anon
LANDSAT atmospheric correction
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anon



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24 Aug 2009 10:17 AM
    Dear all, I am trying to atmospherically correct LANDSAT5 TM and ETM images for a underwater and land cover mapping . I have 2 questions and hopefully someone can give me a light. 1) For TM, I am able to calibrate it and even run the atmospheric correction in flaash module. Nonetheless, as I understand the resulting file should be without units and between 0 and 1 (reflectance) but this is not the case. 2) For the ETM image, I can not even run the calibration. I edit the header, the wavelenghts, the gain and bias. But then i am not able to run the calibration. Could you please help me with this? I would appreciate any help you can give me.    

    MariM



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    24 Aug 2009 12:40 PM
    1) FLAASH always outputs scaled integers to represent reflectance.  This saves on data storage space (pixels stored with 2 byte integers rather than 4 byte floats).  In the FLAASH advanced parameters you can see that there is a scale factor of 10,000. The reflectance cube is scaled by 10,000 to get the values you see. 2) ENVI's Landsat calibration tool requires the file in its original format (FAST, HDF, NLAPS or single band geoTIFF).  We have a patch for ENVI 4.6.1 that will now read the calibration parameters from an original GeoTIFF with metadata (_mtl.txt) that is distributed from the USGS.  This updated support will also be in ENVI 4.7 which will be released soon.  If you would like the patch, you should contact ITT Technical Support directly.
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