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Comment by mikewhy | Hacker News Reader

> I am planning on purchasing drones to calculate NDVI and other useful stuff

As someone who works at a company that uses Drones to do NDVI, look into EVI. And getting a proper calibration plate, or a light sensor you understand, will allow you to make the results much more accurate.

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thanks, I looked at NDWI too http://openweathermap.org/news/post/ndvi-ndwi-differences-an... "NDWI in comparison with NDVI is more accurate indicator of plant humidity. NDWI is calculated with the help of water absorption band which is more closely connected with moisture than chlorophyll whose light-absorbing properties are used in calculation of NDVI. "

I'm not familiar with EVI

Granted I'm just a software developer, we have a whole processing team of GIS people that can go into more detail. And we are focused on vineyards.

Here's a blog post we made to explain the difference, the jist is NDVI can change throughout the day while EVI is more stable: https://skysquirrel.ca/2017/07/evi-vs-ndvi-whats-difference/

Thank you guys I will check out the linked sites; I haven't purchased the drone yet. I do not want to spend, too much (1-2k in €) so maybe I will use a service instead. I am pretty familiar with GIS, and I use it on a regular basis for the orchard (I am experimenting with almond as we have a warmer microclimate here in the valley).

here's a paper looking at which indexes work with corn, wheat and irrigation water, it's very likely each crop will have an index that is more accurate;

"The following spectral indices were examined: Difference Vegetation Index (DVI), Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Difference Water Index (DWI), Normalized Difference Water Index (NDWI), Difference Drought Index (DDI) and Normalized Difference Drought Index (NDDI). "

https://www.degruyter.com/downloadpdf/j/jengeo.2015.8.issue-...

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