Talk:Enhanced vegetation index

What could EVI tell? is the bigger number means more vegetated situation?

Answer: Vegetation Indices, in geneal, and EVI in particular are considered proxy measure of vegetation "greenness", or potential for photoshythesis if you will. So a higher VI (EVI) means the vegetation is healthier, more active, less stressed, more biomass, etc.... In general VI are bounded by -1 and 1, any number soutisde that range should be discarded, and is due to problems with the surface reflectances measured by the sensors and used to derive the VI, or a result of a less than ideal atmosphere correction (the process of canceling what the atmoshepre does to the measurement).

So a negative VI values means the target is either covered with snow/ice, cloud, or water. A positive and high value means more active vegetation, so for example EVI = 0.9 over the Amazon forest and will be 0.05 over the Sahara desert and may be -0.18 over Greenland. These numbers changes (very large change) as vegetation go through its normal growing season cycle or in response to noise in the data (very small change), etc...

External links modified (January 2018)
Hello fellow Wikipedians,

I have just modified 7 external links on Enhanced vegetation index. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20060902144430/http://tbrs.arizona.edu/cdrom/VI_Intro/VI_MOD_VI.html to http://tbrs.arizona.edu/cdrom/VI_Intro/VI_MOD_VI.html
 * Added archive https://web.archive.org/web/20060902144758/http://tbrs.arizona.edu/cdrom/VI_Intro/NDVI_Theo.html to http://tbrs.arizona.edu/cdrom/VI_Intro/NDVI_Theo.html
 * Added archive https://web.archive.org/web/20061219160331/http://edcdaac.usgs.gov/main.asp to http://edcdaac.usgs.gov/main.asp
 * Added archive https://web.archive.org/web/20060915100025/http://tbrs.arizona.edu/cdrom/People/WhosWho.html to http://tbrs.arizona.edu/cdrom/People/WhosWho.html
 * Added archive https://web.archive.org/web/20061230054329/http://tbrs.arizona.edu/cdrom/Index.html to http://tbrs.arizona.edu/cdrom/Index.html
 * Added archive https://web.archive.org/web/20061219160331/http://edcdaac.usgs.gov/main.asp to http://edcdaac.usgs.gov/main.asp
 * Added archive https://web.archive.org/web/20070226154627/http://edcdaac.usgs.gov/modis/mod13q1v4.asp to http://edcdaac.usgs.gov/modis/mod13q1v4.asp

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 19:58, 25 January 2018 (UTC)

Applications of EVI
Section was written much too personally and congratulatory towards the authors of the cited material. I've rewritten it in more neutral and concise language. Halogenated (talk) 01:58, 5 February 2022 (UTC)