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loicdtx / bfastSpatial

Set of utilities and wrappers to perform change detection on satellite image time-series (Landsat and MODIS). Includes pre-processing steps and functions for spatial implementation of bfastmonitor change detection and post processing of the results.
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Tasseled Cap coefficients #51

Closed ceholden closed 8 years ago

ceholden commented 9 years ago

I ran into your LandsatVIs.R calculation of the Tasseled Cap for Landsat TM while trying to figure out the correct coefficients myself. The PDF scan of the Crist 1985 paper from RSE is so horrible that it's hard to see if some coefficients are positive or negative. I found some other papers documenting the coefficients and even found an alternative source for the Crist 1985 that is digitized in better resolution, and these sources show that some of the coefficients your code uses have the wrong sign.

The Crist 1985 rescan is available here and Meddens et al (2013) also published the coefficients in their work available here.

The Wetness coefficient for Band 5 should be -0.6806 and the Greenness coefficient for Band 5 should be -0.0002. Otherwise everything looks correct! I've used the wrong coefficients many times because of the poor quality of the PDF so hope I can help you solve the same small problem.

Cheers

loicdtx commented 9 years ago

Hi Chris, Thanks a lot for spotting the errors and for the links. These TC components always gave us a hard time. We'll fix the code soon. Cheers

bendv commented 8 years ago

I've updated the tc coefficients to just use a single set for SR data for now @ fa4ca0e7e5537535c2212cc566b6cf6b43f77464. I wrote a warning about applying this to OLI data because of bandwidth differences. I'll close this issue for now, but we can always revisit the coefficients as necessary.