Digital Image Processing:A Remote Sensing
Perspective
FW5560
Lecture 13
Vegetation Transformations
Vegetation Spectral
Characteristics and Their
Impact on Transformations and
Indices
Vegetation reflectance is
influence by the structure of
the leaf and its pigmentation
Different leaf pigments
affect spectral signature
Chlorophyll dominantgreen
Carotenoids (yellow/orange
pigment)- 0.40 - 0.75 m.
Two types- xanthophylls
and carotenes- absorb blue
light. Protect the
cholorphyll from
photodamage.
Dominant Factors Controlling Leaf Reflectance
Vegetation Indices- widely used transformation for 2 reasons:
Certain aspects of the shape of spectral reflectance curves of
different earth surface cover types can be enhanced by ratioing.
Undesirable effects on the recorded DNs such as variable
illumination caused by variations in topography can be reduced.
From: CampbellIntroduction to
Remote Sensing
Healthy vegetation reflects strongly in the near-infrared portion
of the spectrum while absorbing strongly in the visible red.
Soil and water, show near equal reflectances in both the nearinfrared and red portions.
Thus, a ratio image of Landsat ETM+ Band 4 (Near-Infrared - 0.8
to 1.1 mm) divided by Band 3 (Red - 0.6 to 0.7 mm) would result
in ratios much greater than 1.0 for vegetation, and ratios around
1.0 for soil and water. The discrimination of vegetation from
other surface cover types is significantly
enhanced. Better able to identify areas of
unhealthy or stressed vegetation, which
show low near-infrared reflectance, as
the ratios would be lower than for
healthy green vegetation.
Reflectance Response of a Single Magnolia Leaf
(Magnolia grandiflora) to Decreased Relative Water Content
Infrared/Red Ratio Vegetation Index
The near-infrared (NIR) to red
simple ratio (SR) is the first
true vegetation index:
NIR
SR 
red
It takes advantage of the inverse
relationship between chlorophyll
absorption of red radiant energy
and increased reflectance of
near-infrared energy for healthy
plant canopies (Cohen, 1991) .
Normalized Difference Vegetation Index
The generic normalized difference vegetation index (NDVI):
NIR  red
NDVI 
NIR  red
has provided a method of estimating net primary production over
varying biome types (e.g. Lenney et al., 1996), identifying
ecoregions (Ramsey et al., 1995), monitoring phenological
patterns of the earth’s vegetative surface, and of assessing the
length of the growing season and dry-down periods (Huete and
Liu, 1994).
Using and Ecoregion Framework to Analyze Land Cover and Land Use Dynamics, Gallant et al, 2004,
Environmental Management
Perpendicular
Vegetation Index
Soil Line PVI = 0
Water PVI < 0
Vegetation PVI > 0
PVI measures the
orthogonal distance
from the pixel in
question to the soil
line.
Evaluation Of Landsat-5 Thematic Mapper Data For Detecting Potential Construction
Areas For Intensified Housing, Thomas J. Blaser, Ronald J.P. Lyon and Kai Lanz 1990,
Geoscience and Remote Sensing Symposium, 1990. IGARSS '90. 'Remote Sensing Science
for the Nineties, 10th Annual International
Phenological Cycles of
San Joaquin and Imperial
Valley, California Crops
and Landsat
Multispectral Scanner
Images of One Field
During A Growing
Season
Distribution of Pixels in a Scene in
Red and Near-infrared Multispectral Feature Space
Kauth-Thomas “Tasseled Cap” Transformation