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eMapR / LT-GEE

Google Earth Engine implementation of the LandTrendr spectral-temporal segmentation algorithm. For documentation see:
https://emapr.github.io/LT-GEE
Apache License 2.0
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ROY coefficients #30

Closed lucas-johnson closed 9 months ago

lucas-johnson commented 2 years ago

Hello - thanks for an amazing set of tools and documentation! This has all been so helpful.

I noticed the warning about the use of collection 2, and the decision to not use the ROY coefficients for scaling. Looking a bit deeper I noticed the following note: https://github.com/eMapR/LT-GEE/blob/5d70f99bf81a87401fe2520258cb9426884743ae/LandTrendr.js#L107

Could you provide any more insight into those use cases around the world? Maybe some studies? Thank you!

colettembrown commented 2 years ago

Hello! Following up to see if anyone has a workaround for the Collection 2 Landsat data and harmonizing without the Roy coefficients, or what is causing the issue with these coefficients? Thank you for any tips / thoughts!

clarype commented 1 year ago

I am tolled, they didn't make a big difference with the implementation of Collection 2. My colleague conducted an unpublished analysis on many locations around the world, and did not find a large difference between the corrected Collection 1 and the uncorrected Collection 2. I will see if I can get more info.

colettembrown commented 1 year ago

Can you send me the unpublished analysis? Or potentially how they determined C1 and C2 could be harmonized in the same way? This sounds like great news.

On Thu, Dec 15, 2022 at 10:43 AM Peter C @.***> wrote:

I am tolled, they didn't make a big difference with the implementation of Collection 2. My colleague conducted an unpublished analysis on many locations around the world, and did not find a large difference between the corrected Collection 1 and the uncorrected Collection 2. I will see if I can get more info.

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jdbcode commented 1 year ago

This might help: https://developers.google.com/earth-engine/faq#is_cross-sensor_landsat_surface_reflectance_harmonization_needed