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Remote sensing for resources development and environmental management
Damen, M. C. J.

tion of the reflected energy by a sensor carried on
a data collection platform. According to energy-
matter relationships different objects reflect ener
gy differently in frequency, direction and inten
sity. This permits to compose images with contrasts
for reflected energy coming from different direc
tions. In order to obtain object information data
processing is required.
As a photogrammetrist I see mainly two data stream
types: the one for topographic information by the
photogrammetric restitution process; and the other
for thematic information by the image interpretation
process. All of this information is only useful to
me, if I can bring it into a geographic reference
base, that is to say, if I can describe it in form
of a map. I realize, that these definitions not
include e.g. laser sensing methods of atmospheric
profiles, radar altimeter and scatterometer measure
ments of the sea surface, nor do they pertain to
seismic, geomagnetic nor gravimetric methods, which
some atmospheric physicists or some geophysicists do
consider as remote sensing.
The development of remote sensing, according to my
suggested definition is as old as the first photo
graph taken by Niepce in 1839. It was the balloon as
a platform, introduced by Nadir in the 1850's which
brought the first military application of remote
sensing in the form of photographic interpretation
of the battlefield of Solferino.
Also in the US battlefields were soon photographed
during the civil war. World War I began to use the
airplane as a platform for the same purpose, and
nothing has changed much in the purpose of military
reconnaissance since then, except the tools and
their analysis techniques.
The false color infrared film is such a military
development. Another was the development of a ther
mal infrared scanner. A third was the construction
of an airborne radar. These sensors were classified
in the early 1960's and therefore through the Infra
red Laboratory of the University of Michigan, which
later became the Environmental Research Institute of
Michigan ERIM and through the activities of Profes
sor Colwell at Berkeley the term remote sensing was
introduced to data analysis with these new sensors
including photography as well. This was still the
time ITC established photo-interpretation institutes
in cooperation with for example India and Colombia.
In the meantime these institutions, like the ITC
heavily engage in remote sensing. This has come
about through the space activities, started in 1957
with Sputnik in the USSR and followed shortly by the
United States of America. Already in 1960 the US
launched its first weather satellite Tiros and is
operating now under NOAA two polar and two geo
stationary satellites, which observe the earth's
atmosphere in the visible and the infrared spec
The European Space Agency ESA and Japan have
joined in with their weather satellites Meteosat
and GMS, while the USSR has its own meteorological
program. Remote sensing has in the 1960's in the
USA followed the path of lunar exploration, with
Lunar Orbiter utilized for mapping landing sites on
an analog basis. The Lunar Landing has been the
primary goal of exploration.
However, the planets required for their explo
ration from the mid-60's on imaging by digital
systems. Landsat, launched in 1972 immediately
provoked worldwide interest in the data, as ex
pressed by the many receiving stations operating
around the globe. During the last fourteen years
remote sensing has gone with the Landsat program
around the world as a new technology and as a new
Let us be reminded, that the status of world
mapping, as expressed by UN surveys in 1980 is by
no means adequate. Nor will it be possible to sig
nificantly reduce the lack of maps by existing
In contrast to that Landsat MSS, during the first
eight years of its operation was able to provide a
morefold coverage of almost every part of the
globe. It has taken about hundred years to map the
territory of the Federal Republic of Germany by
classical ground survey tools at medium scales. We
can do that today by photogrammetry in about ten
There is hope that satellite imaging might permit
us to do that in about one year, but it must do so
with sufficient quality.
The Landsat Multispectral Scanner has since 1972
provided color composites for analog photographic
It is quite obvious that only digital processing,
that is grey level stretch for each channel and
contrast enhancement through local filter oper
ations permit to look at a superior product.
Despite of this digital processing Landsat MSS
imagery with its 80 m pixels reaches a resolution
Already in 1973 it became clear, that high resol
ution systems, such as the Skylab 190A photographic
camera yields higher resolutions with about 20 m
pixel equivalents. We therefore have a multitude of
sensor systems available in remote sensing and none
has fully replaced the other.
Since satellite sensors are usually designed by
industry or by governments not according to the
requirements of practice, but according to hardware
and funding interests and limitations, it is better
for the user to compare the requirements by simu
lations. Let us take the example of topographic
mapping at 1:50.000, a key task for the economy of
the world. A comparison showing Landsat data and
the corresponding map 1:50.000 at the same scale
proves that Landsat MSS in inadequate to map cul
tural features at that scale.
We know that 1:50.000 mapping can be done from
1:50.000 stereo aerial photographs. If one digi
tizes this imagery at varying intervals using a
drum scanner, as shown here for 40 m pixels, then
one can plot the topographic information in a
stereo-plotter. The result of such a test in which
pixel sizes in mono and stereo were used at 2 m,
5 m, 10 m, 20 m, 40 m intervals, gave the indica
tion that a 5 m pixel size is required for stereo
restitution at the scale of 1:50.000.
Among the existing imaging satellites of high
resolution we must distinguish between those of
pure remote sensing interest suitable for thematic
cartography only, and between cartographic satel
lites, which provide full 3D mapping capability by
stereo imaging.
Landsat MSS is usually displayed as false color
composite in 80 m pixels. The four channels permit a
supervised multispectral classification to determine
landuse. Unfortunately the classification precision
for certain classes, like settlements is still too
low. A better result is obtained when Landsat clas
sifications are superimposed with map data.
This is primarily so when Landsat TM data with 30
m pixels or SPOT Data with 20 or 10 m pixels are
combined; or if the experimental systems of space
photography from Spacelab 1 with 8 m pixel equi
valents and with the Space Shuttle LFC with better
than 5 m pixel equivalents are used.
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