ASTER bands 4-5-6, too high negative values

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Last Post 15 Mar 2019 06:51 PM by joseph kafka

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joseph kafka

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Posts:2

15 Mar 2019 02:38 AM
After Radiometric Correction -> FLAASH Atmospheric Correction, ASTER L1T bands 4 - 5 - 6 has too high negative values. I've used "Aerosol model, Aerosol Retrieval - None" as the area is a terrain region. Is it normal to get such high negative values ? Basic Min Max Mean Stdev Band 1 -686 4696 485.896568 400.115968 Band 2 -263 5461 580.587626 504.316090 Band 3 -639 6975 1484.227743 1133.655309 Band 4 -706 144 -141.317726 123.189226 Band 5 -326 101 -122.237353 93.004298 Band 6 -192 396 -20.122247 33.731257 Band 7 -139 2345 283.934617 241.587458 Band 8 -257 4817 562.759392 483.038908 Band 9 -178 3406 448.227688 370.067917

MariM

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15 Mar 2019 05:54 AM
It is not uncommon to have negative values in dark areas such as water and shadow. It means the detected radiance in these areas was too low to model well. You can mask values below 0 and set them to 0 or other data ignore value. Also, be aware that the output from FLAASH is scaled by 10000. This means a value of -686 is -0.06% reflectance, which is essentially 0 reflectance.

joseph kafka

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