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Hoping someone can short circuit a lot of exploration

Landsat 8 values are stored as unint16 since the sensors work on a range 0 to 4096 whereas the L7+TM was 8 bit and had a digital number range 0 to 255. USGS link

Looking at the unprocessed bands in QGIS, the value tool reports values of ~8000 for band 3, whereas GRASS reports values of ~0.19 . For the same bands in L7+TM band 3 values are ~30

Understandably, the output from my old workflow in GRASS is giving nonsense. i.landsat.toar does read L8 but with the funny numbers I don't expect it is on the right track.

The end use is NDVI, I don't expect a pansharpening workflow to be the same.

Any tips on a new workflow?

  • I guess this question touches on the same issues, but to reclass would be experimenting, hoping someone has some detailed knowledge gis.stackexchange.com/questions/39174/… – Willy Aug 19 '13 at 13:17
  • It's clear that TOAR reads the dn as less than 1, the following from the verbose output of the module BAND 1 (code 1) calibrated digital number (DN): 0.0 to 0.0 calibration constants (L): -0.000 to 0.000 at-surface radiance = 0.00000000 * DN + -0.000 mean solar exoatmospheric irradiance (ESUN): -0.000 at-surface reflectance = radiance / 0.00000 the darkness DN with a least 1000 pixels is 1 the DN mode is 0 – Willy Aug 19 '13 at 13:31
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The i.landsat.toar version included in Grass7 supports the new Landsat8 OLI/TIRS sensor and worked flawless in my tries. One thing you have to be careful is that Landsat 8 has different band designations. So band 3 on Landsat 7 is equivalent to band 4 on Landsat 8.

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