Enhanced Vegetation Index {LSRS}

Enhanced Vegetation Index

Description

In areas of dense canopy where the leaf area index (LAI) is high, the NDVI values can be improved by leveraging information in the blue wavelength. Information in this portion of the spectrum can help correct for soil background signals and atmospheric influences. The enhanced vegetation index (EVI) is an 'optimized' vegetation index designed to enhance the vegetation signal with improved sensitivity in high biomass regions and improved vegetation monitoring through a de-coupling of the canopy background signal and a reduction in atmosphere influences. EVI is computed following this equation:

VALUE = 2.5*(NIR - Red) / (NIR + 6*Red - 7.5*Blue + 1)

Usage

EVI(a="NIR",b="Red",c="Blue",Pixel.Depth)

Arguments

a

NIR satellite band (format:TIF)

b

Red satellite band (format:TIF)

c

Blue satellite band (format:TIF)

Pixel.Depth

for satellite image with digital numbers (DN) of 0 to 255,Pixel.Depth=null and for the larger DN, Pixel.Depth=1

Note

in some cases for satellite image with very large digital numbers it need to be multiplied with 0.1,0.01,.001,...

Author(s)

Mehdi Sarparast

References

[1] A. Huete, K. Didan, T. Miura, E. P. Rodriguez, X. Gao, L. G. Ferreira. Overview of the radiometric and biophysical performance of the MODIS vegetation indices. Remote Sensing of Environment 83(2002) 195-213.

Examples

## The function is currently defined as
function (a = NIR, b = Red, c = Blue,Pixel.Depth)
{
name=EVI(a,b,c,Pixel.Depth=null)
areaXY <-c(xmin, xmax, ymin, ymax)
cropXY <- crop(name, areaXY)
plot(cropXY,lwd=4,  main="EVI",xlab="easting", ylab="northing")
hist(cropXY,   main="EVI",
     xlab="EVI",col="red", ylab="Frequency of Pixels")
  }