R. S. A. T.
Spectral Analysis
over the
New York City Region
LANDSAT Thematic Mapper data measures light in seven bands
of the electromagnetic spectrum. Each of these bands, or wavelength
ranges, can be viewed individually as a black-and-white, or panchromatic,
image; or they can be viewed in combination with other bands to
produce color composites. In single-band images, energy intensity
is represented in varying tones of gray. The raw, unprocessed,
grayscale imagery can be enhanced in a variety of ways to increase
image detail and improve our ability to differentiate features
on the ground. Color imagery is usually produced by combining
three single-band images in a computer and assigning the colors
red, green or blue to each band. The variety of possible combinations
from the seven TM bands provides a means for isolating specific
features of interest through different color combinations.
Individual Bands
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3 Band Color Composites
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The above image icons are links
to a series of pages that illustrate the differences among spectral
bands and the more commonly employed band combinations to produce
color composites. Also presented is a comparison of single-band
raw, unprocessed data to digitally enhanced imagery. Two areas
are used to illustrate the information: a sub-sampled full scene
over New York, Connecticut and Long Island; and a larger scale
(smaller area) over Manhattan.
Copyright © 2001, Systems for World Surveillance,
Inc.
all rights reserved
sws@rsat.com
