How to write the formula for Enhanced Vegetation Index (EVI) in Raster Calculator?

[StephenChignell]

Hi everyone,
I'm trying to derive Enhanced Vegetation Index (EVI) from Landsat 5 TM data using the raster calculator and I can't seem to get the output I want. Here is a link to the description and formula for EVI:

http://en.wikipedia.org/wiki/Enhanced_vegetation_index


The output should be a raster with values ranging from -1 to 1, but I get values from like 30-40 which is incorrect.

Right now my formula looks like this:


2.5 * (Float("%Band 4%" - "%Band 3%") / Float("%Band 4%" + 6 * "%Band 3%" - 7.5 *"%Band 1%" + 1))


Does anyone see something in here that doesn't make sense-- or even better--a formula I could copy/paste?

Thanks!