I have calculated EVI2 using landsat 7 surface reflectance images and I am getting values above 1.25 (mathematical maximum for EVI2 based on the formula) in my study area (heavily vegetated). I get a range between 0.2 and 1.8. Many publications stipulate -1 to 1, especially based on MODIS data. I also did a check with Landsat 7 TOA images, and I get ranges from -1 to 1, as the publications say. Does this mean something is wrong with the Landsat 7 surface reflectance images, or should values above 1.25 still be okay?
Shivan Kebirungi,
Nothing wrong with the Landsat 7 images, and the values are correct. EVI2 [-1, 1.25]
Have a look at this discussion, you'll find details of calculation and the "why" of out of range.
https://www.researchgate.net/post/Hello-does-anyone-know-the-range-of-output-values-for-EVI2-I-know-NDVI-is-between-1-to-1-Thank-you
It is absolutely fine and fair to get values above 1.25 as you are using a surface reflectance imagery and sine you mentioned that the area is heavily vegetated, the values reflect the colour composite and type of strata so the number and the work is acceptable.
Best wishes and good luck !
Prachi Ugle
This is very helpful! I guess most people use TOA images instead of SR to compute the EVI2 index. No problem!
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