# EVI2 value calculated from MODIS MOD09Q1 not bounded by -1 to 1

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.

• @Luke you're right, that was my issues! thanks for the correct answer. I'm new here and I'm not seeing how to mark your comment as the answer yet.. can't upvote or anything. Oct 22 '18 at 16:21
• I've converted my comment to an answer. You can mark it as accepted using the tick between the voting buttons Oct 23 '18 at 9:01

``````2.5(NIR*0.0001-Red*0.0001)/(NIR*0.0001 + 2.4*Red*0.0001+1)