I'm trying to derive from MODIS 8 day composite MOD09Q1.006 product
My formula follows the standard interpretation:
EVI2 = 2.5(NIR-Red)/(NIR + 2.4*Red+1)
I already know that MODIS bands for NIR and Red have a scaling factor applied, and when I say "-1 to 1" I know I'm really expecting values to lie between -10000 and 10000.
My surface reflectance Band 1 and 2 (RED and NIR) values range from -100 to 16000 as they should.
When I perform my calculation for EVI using the previously mentioned formula, I have a wide range of values including roughly fitting between -25,000 to 25,000.
This leads to my question: How am I supposed to expect EVI2 values to fall between -1 and 1? Is there some kind of transformation I should be applying to my band values? With the multiplier of 2.5 in the formula, I see that the the function converges at 2.5 (thus those 25,000 values) as NIR approaches infinity.