0

Anyone know how the Landsat NDVI composite image collections on Google Earth Engine are developed? I'm wondering if GEE masks clouds and cloud shadows? If they are performing a reducer on all NDVI images, what reducer are they using? Average or median, perhaps? I can't find any documentation in the Chandler et al. (2009) paper that GEE references nor anywhere else so I'm guessing there's no cloud masking. If that's the case, what use is this image collection since most NDVI analysis seems to require cloud and shadow masking and there's no quality/cloud bands in these composites to cloud mask with.

I like these composites because they are already preprocessed to monthly and annual values and much easier to work with.

Examples: https://developers.google.com/earth-engine/datasets/catalog/LANDSAT_LC08_C01_T1_32DAY_NDVI

https://developers.google.com/earth-engine/datasets/catalog/LANDSAT_LC08_C01_T1_ANNUAL_NDVI

1 Answer 1

0

The GEE composites do not cloud mask. I've been used to exporting pixel values only, and forgot to inspect some visual examples. The GEE composites show clouds as an NDVI range, mostly white, but not pure white (empty) like a masked pixel should be, right? Shadows and cloud edges especially look like NDVI values, but incorrect for the actual underlying pixel vegetation.

So these Google-created composites only seem useful for browsing imagery, not for analysis.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.