Normalized Difference Vegetation Index (NDVI) Distinct colors (wavelengths) of visible and near-infrared sunlight reflected by the plants determine the density of green on a patch of land and ocean.

1. NDVI
Normalized Difference Vegetation Index

2. NormalizedDifferenceVegetation Index (NDVI)
•Distinct colors(wavelengths) of visible and near-infrared sunlight reflected by
the plantsdetermine the density of green on a patch of landand ocean.
•The pigment in plantleaves, chlorophyll, strongly absorbs visible light (from
0.4 to 0.7 μm) for use in photosynthesis. The cell structure of the leaves, on
the other hand, strongly reflects near-infrared light (from 0.7 to 1.1 μm).
•The more leaves a plant has or the more phytoplankton thereisin the column,
the more these wavelengthsof light are affected, respectively.

3. (courtesy http://earthobservatory.nasa.gov)
NDVI= (NIR — VIS)/(NIR + VIS)
Calculationsof NDVI for a given
pixel alwaysresult in a number
thatranges from minus one (-1)
to plus one (+1)
-- no green leaves gives a value
close to zero.
-- zero means no vegetation
-- close to +1 (0.8 - 0.9)
indicatesthe highest possible
densityof green leaves.