[GRASS-user] EVI algorithm

[Markus Neteler]

On Wed, Jul 4, 2012 at 10:34 AM, Danut Mihon <danut_mihon at yahoo.com> wrote:
> Here is the code:
>
>
> r.in.gdal input=band1 output=in1 location=intermediary
> g.gisenv set=LOCATION_NAME=intermediary
> r.in.gdal input=band3 output=in2
> r.in.gdal input=band4 output=in3
> r.mapcalc aux="(2.5*(image2-image1)/(image2+ 6.0 *image1-7.5 *image0+1.0))"
> r.colors map=output rules=evi
> r.out.tiff input=output output=out1.tif
> r.out.gdal input=output output=out1.tif

OK, looks right to me comparing with the link below.
But...

On Thu, Jul 5, 2012 at 9:13 AM, Danut Mihon <danut_mihon at yahoo.com> wrote:
> the EVI formula is on this page
> (http://en.wikipedia.org/wiki/Enhanced_vegetation_index).

What is the range of the input images? MODIS data are usually
scaled. Did you rescale outside of GRASS beforehand?

Markus