Can I perform FLAASH correction on airborne SASI hyperspectral

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Last Post 23 Jun 2017 06:04 AM by MariM

Can I perform FLAASH correction on airborne SASI hyperspectral images

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gou sheng

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Posts:13

20 Jun 2017 06:17 PM
Hi, I have collected airborne hyperspectral SASI images (950 nm ~ 2450nm), and want to convert the raidance to reflectence by performing FLAASH. However, when I perform FLAASH atmosphere correction module in ENVI, it shows the following error "ACC_AVHEAD: Error -- some channels found outside 100 to 30000 cm-1". So I want to know can I use FLAASH module to perform an atmospheric correction on SASI images? If I cannot directly perform, can I "join" CASI and SASI spectra and choose the sensor type as 'CASI' in FLAASH correction parameter setting panel? Or I have to use other methods to perform atmospheric correction on SASI images, such as "QUAC" and "Log Residuals" to get relative reflectance? Thank you!

MariM

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Posts:2396
Veteran Member

21 Jun 2017 09:34 AM
Can you check the wavelengths and units in the image header to make sure they match (either in nanometers or micrometers)? I believe this might be caused by a mis-match. You could likely combine your CASI and SASI as long as the images are co-registered to each other and have the appropriate wavelengths, fwhm (if available) assigned. Also be sure that you are using the appropriate scale factor, which is divided into the data to convert the data to µW/(cm2 * sr * µm). Quac is also a very reasonable alternative - it also produces apparent reflectance but using a different method. With this method, be sure to create a mask of background values that should be excluded from baseline estimation and endmember extraction for best results.