# EVI calculation from UAV multispectral survey

I want to calculate EVI index from UAV multispectral survey. For satellite imagery it is pretty straightforward (after reading multiple posts on GIS.SE) but not sure how to approach this problem, when imagery is collected from approx. 120 meters and atmospheric correction is not required in such extent.

Can somebody give me a tip how to build the equation in QGIS raster calculator to get proper EVI values?

What vaules should I assign for the "G", "C1", "C2" and "L" coefficients?

``````EVI = G X ((NIR - RED)/ (NIR + (C1 x RED)-(C2 x BLUE) + L))
``````
• Could you please state the lat and long of your flight location? Commented May 22, 2018 at 13:36
• Have you considered just using NDVI? If your AOI and altitude dont suffer from the conditions that EVI coefficients where designed to compensate for, then why bother using EVI at all?
– Rex
Commented May 22, 2018 at 14:21
• Most of these equations use empirical calculations, so I guess try to do a regression with your image values or a PCA to test the weights of your area. Commented May 22, 2018 at 17:58
• In this case I do not have specific location, but definetely working in Poland generally. With regard to NDVI, it does not provide results I expect and results vary depending on time of a day slightly even using calibration panels. This is why I am trying to explore other possibilities and EVI was advertised as lighting conditions independent, more reliable index. Commented May 23, 2018 at 11:02
• George - I am not as good in remote sensing :) Can You provide me with a some guidance how to approach this? Any research paper? Would love to try this as well but do not know how to bite that stuff... Commented May 23, 2018 at 11:04

The common definitions for these coefficients when using MODIS are: `L=1, C1 = 6, C2 = 7.5`. The `C1` and `C2` coefficients are aerosol resistance terms that rely on the blue band to partial out atmospheric influence in the red band. The gain is commonly defined as 2.5
``````two.band.evi = 2.5*((nir - red)/(nir + 2.4 * red + L)) where; L=1