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Geospatial maps for agricultural mapping and monitoring uses have been made
for many decades based on the well-known Normalized Difference Vegetation
Index (NDVI) formula, which was first proposed in the late 1960s as a
better way to combine two bands of multispectral (MS) digital image values
when making sets of vegetation-vigor condition indicator values as
vegetation vigor varies spatially over an area of interest and/or
temporally over a given span of time. The simplicity of the NDVI formula
has made it and continues to make it very attractive as an algorithm
vegetation vigor mapping and monitoring.

However, in the late 1980s, a better, physical understanding was gained
about how electromagnetic radiation interacts with vegetation and soils.
This led to the Soil Adjusted Vegetation Index (SAVI) formula and its many
variants as ways to make vegetation-vigor maps that are physically-based
and hence that are better than those maps that are made by the NDVI formula.
Nevertheless, the use of the NDVI formula is still dominant today.
Unfortunately, many NDVI map vendors use poor-quality and often
uncalibrated MS images when making an NDVI map. And, since each NDVI map is
based on only two spectral bands ... usually a red-light band and a
near-infrared pair of images, information in other MS bands is left behind.
This is especially true when the source of MS imagery includes many more
than just the NDVI-related pair of spectral bands.
As the number of imaging systems have increased dramatically and as this
expansion is set to expand even more so in 2016 and as the spatial
resolutions of these sources are getting smaller and smaller ... even down
to centimeter sizes, a challenge exists regarding how best to take
advantage of these many bands and frequent revisits. Dr. Paris will be
presenting information about the history of vegetation and soil mapping
with the hope that better standards will be adopted by the whole
remote-sensing community and that better information maps will be made for
customers ... Beyond NDVI ... in 2016.


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David Alvarez

“THE FURTHER BACKWARDS YOU LOOK, THE FURTHER FORWARD YOU CAN SEE"

Winston Churchill

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