[GRASS-dev] Descriptions for r.colors color rules

[Markus Neteler]

On Jan 25, 2008 12:08 AM, Hamish <hamish_b at yahoo.com> wrote:
> > Eric Patton wrote:
> > > I was updating the r.colors docs, as the given rules in the html
> > > are out of sync with the program.
> > > I'm not sure how to describe some of the canned rules, particularly
> > > curvature and evi.
...
> It is enhanced vegetation index from eg MODIS data like NDVI.
> see  http://earthobservatory.nasa.gov/Library/MeasuringVegetation/

EVI (enhanced vegetation index) is used to monitor vegetation.
EVI was developed with improved sensitivity in areas of dense,
green vegetation with large amounts of chlorophyll (where NDVI tends
to saturate). Additionally, it is less sensitive to haze and atmospheric
effects since the blue channel is included in the denominator. It also
minimizes the influence of background interference caused by bare
soil reflecting off the ground.

chees
Markus