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micasense / imageprocessing

MicaSense RedEdge and Altum image processing tutorials
https://www.micasense.com
MIT License
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Question: reflectances above 1.0 in vegetation indexes calculation #171

Open Wuffels opened 2 years ago

Wuffels commented 2 years ago

Hello! In "MicaSense RedEdge Image Processing Tutorial 1" is said it is normal that some parts of a converted reflectance image show reflectances above 1.0. My question: how can i use this values for vegetation indexes calculation? Can I use this values (above 1.0) "as is" or I need to make some preprocessing operations? It has no affect for something like NDVI, but some indexes (EVI, SAVI etc.) use constants. Is it correct to use values above 1.0 in such indexes? Thank you!

poynting commented 2 years ago

If the reflectance is higher than 100%, it's likely due to some specular reflections. Specular reflections can vary quite dramatically by waveband. It would be most prudent to mark these pixels as invalid for analysis purposes.