The document discusses the Normalized Difference Vegetation Index (NDVI), which uses visible and near-infrared light to analyze remote sensing data and determine the presence of live green vegetation. NDVI values increase with more vegetation, as leaves strongly absorb visible light and reflect near-infrared light. However, at very high vegetation levels, small NDVI changes may represent large changes in plants. NDVI values can also be influenced by soil, particularly in areas with 45-70% plant coverage, leading to soil-adjusted vegetation indices being developed.

3. Based on source of
energy
 Passive; source of energy
is either Sun or
Earth/Atmosphere.
 Active; source of energy
is Remote Sensor
system(RADAR).
 Example, Camera takes
photo With or Without
flash.
 Optical; operate in the visible,
near infrared, middle infrared
and short wave infrared portion.
 Thermal; operate in thermal
range of electromagnetic
spectrum record, the energy
emitted from the earth features.
 Microwave; records the
backscattered microwaves and
are independent of weather and
solar radiations.
Based on range of EMS
Source; Google

5. Normalised Difference
Vegetation Index

6.  The Normalized Difference Vegetation Index (NDVI) is a
numerical indicator that uses the visible and near-infrared bands
of the electromagnetic spectrum, and is adopted to analyze
remote sensing measurements and assess whether the target
being observed contains live green vegetation or not
 When sunlight strikes objects, certain wavelengths of this
spectrum are absorbed and other wavelengths are reflected. The
pigment in plant leaves, 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,
the more these wavelengths of light are affected, respectively.
Source: Earth Observatory

7.  Vegetation appears very different at visible and near-infrared
wavelengths. In visible light (top), vegetated areas are very dark, almost
black, while desert regions (like the Sahara) are light. At near-infrared
wavelengths, the vegetation is brighter and deserts are about the same.
By comparing visible and infrared light, scientists measure the relative
amount of vegetation. (The variation in shade is more apparent in the
detail of the U.S. West Coast).
Source: Earth Observatory

9.  As the amount of green
vegetation increases, the change
in NDVI gets smaller and
smaller. So at very high NDVI
values, a small change in NDVI
may actually represent a very
large change in vegetation. This
type of sensitivity change is
problematic for analysis of areas
with a high amount of
photosynthetically active
vegetation.
 In these situations, it may be
advisable to use another
vegetation index with better
sensitivity to high-vegetation
cover situations like
the Enhanced Vegetation
Index or the Wide Dynamic
Range Vegetation Index.
 Light from the soil surface can
influence the NDVI values by a
large degree. . Heute and
Jackson (1988) found that the
soil surface impact on NDVI
values was greatest in areas with
between 45% and 70% vegetative
cover.
 This limitation was the reason
for the development of the
several different soil-adjusted
vegetation indices (e.g., Soil-
adjusted Vegetation Index &
Modified Soil-adjusted
Vegetation Index
Source; Wikipedia