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Steele, Mariah; Zilist, Svetlana (ed.) / Wisconsin engineer
Volume 97, No. 4 (October 1993)

Wolff, Jesse
Environmental remote sensing,   pp. 14-16


Page 14


Environmental Remote
Sensing
Since the dawn of the atomic age,
people have become more critical of the
technology that engineers introduce to
the world. Technology is expected to
improve our quality of life without
harming to world we live in. To do this,
we need to understand the effects that
technology has on our environment. We
all know about the hole in the ozone
layer and the possibility of global
warming, but how are these problems
detected? Remote sensing of the environ-
ment provides a practical way to monitor
our world and to identify problems in the
way we manage the Earth's resources.
Numerous departments at UW-
Madison are involved in remote sensing
education and research. Civil and
Environmental Engineering makes up
the core of the program, while the
Institute for Environmental Studies offers
a strong curriculum in Environmental
Monitoring. Forestry, Geography, Soil
Science, Botany, Computer Science and
many other departments are also
involved, making the study of environ-
mental remote sensing available to a
wide range of students.
THE TECHNOLOGY
Remote sensing, or sensing from a
,2y
(di Re        I..smisan
through the
cos(a) Sources ofenergy      atmsosphere  ro
\(b) Popagpaios th-  -ugh/
Sens&n syslm-
(, trtsrlmlaures
distance is accomplished through
airborne or satellite monitoring of the
Earth. The satellite weather maps on the
evening news are one common applica-
tion of remote sensing. In a remote
sensing system energy covering a broad
- - o_ _f thy, ola- r1
Referenee
lel
Pictorial               VIsual
Digital                 Digital
If)                     Ig)                    (hI
Date products          Interpretation           Inormetio
and analysis             products
Ise
detail. Once the area is captured on film,
the photo is usually scanned into a
computer which changes it to a digital
image. It can then be analyzed both by
the human eye and with computer
methods just as a digital image from a
s2salie  e
magnetic spectrum is
recorded. This
ranges from ultravio-
let light and visible
light to radio waves.
The energy is
captured on photo-
graphic film from
aerial monitoring or
in a digital image
from a satellite. The
photo or image is
then interpreted and
analyzed resulting in
information about
our environment
(see figure 1).
Airphoto
interpretation, or the
identifying objects on an aerial photo-
graph, is a widespread method of remote
sensing. Aerial photography provides the
only means of capturing a relatively
small area of land in a high degree of
'JaLeiLe t: r.
Although aerial
photography
provides a highly
detailed record of
the land, it is
impractical for
many applications
because it is often
inconvenient to
get flights off, and
if data needs to be
collected on a
regular basis,
many flights are
required. Also
only energy in or
near the visible
part of the
spectrum can be
recorded on photographic film, again
limiting the use of airphoto interpreta-
tion.
If the high resolution that an aerial
photo provides is not required, remote
sensing from space is the most practical
and complete method of acquiring data
about our environment. By using
satellites to monitor the Earth, it is
possible to look at every part of the Earth
approximately once every 16 days. To
date, five U.S. Landsat satellites and a
SPOT satellite put up by France have
been used to collect images. The first
three Landsat satellites used a multispec-
tral scanner (MSS) to look at four broad
areas of the spectrum(green, red, and two
near infrared bands). They had 80 meter
resolution as compared to 30 meters
accomplished by Landsat-4 and 5 which
in addition use a Thematic Mapper (TM).
The Thematic Mapper looks at seven
narrow areas of the spectrum(blue,
green, red, and four infrared bands).
Figures 2 through 4 show the differences
between an aerial photograph and
images from the MSS on Landsat-3, and
Wisconsin ®@ng1nnQ<, October 1993
DATA ACQUISITION  ======>  DATA ANALYSIS
FIGURE I       Electromagnetic remote sensing at earth resources.
14


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