How to Interpret Enhanced Vegetation Index( EVI) Values ?

970
0
11-27-2019 11:05 PM
AshadAlif
New Contributor

Im working on calculation of Calculation of Enhanced Vegetation Index(EVI) From Landsat 5 TM and Landsat 8 OLI Using ArcMap 10.4.1. As far i know to Calculate EVI, first it needs to Convert the DN Values to Physical TOA reflectance. For Landsat 5 TM, I did that steps (First I converted DN to Radiance and then to Reflectance and 

got the refelectance Values of the required bands ranging between 0 to 1 (Band 1 =0 to 0.367, Band 3= 0 to 0.648, Band 4= 0 to 0.808).

Then I applied the Formula for Deriving EVI= 2.5 * (("Band 4" - "Band 3") / "Band 4" + 6 * "Band 3" - 7.5 * "Band 1" + 1) in Raster Calculator and got result with EVI Ranging -1822.42 to 12.71 (!) . If i clip my Area of Interest Still get the Value ranges between -0.658 to +2.95.EVI Raster (AOI) depicting values ranges Between -0.658 to +2.947EVI Raster depicting values ranges Between -1822.42  to +12.71

I used to know that EVI ranges between -1 to +1 , However USGS says The valid Range is between -10,000 to +10,000) see https://www.usgs.gov/land-resources/nli/landsat/landsat-enhanced-vegetation-index?qt-science_support... And i know EVI is not a Normalized Index like NDVI.

Now I really Want to know if my precedure is okay, and then how can I interpret The values? (eg. Vegetation, Bare Soil etc). And If not then how can I Correctly Calculate EVI?

0 Kudos
0 Replies