TM 5-852-2/AFR 88-19, Vol. 2
CHAPTER 3
SITE SELECTION
3-1. General.
(2) In the 1982 the Thematic Mapper (TM)
sensor was launched on Landsat 4. The Thematic
a. Aerial imagery. The general remoteness and
Mapper sensor is a mechanical line scanner device,
undeveloped nature of much of the world's arctic
similar to the MSS. However, it scans and obtains
and subarctic regions pose special problems in
data for six scan lines in both directions during the
acquiring adequate terrain information to plan and
scanner sweep. The MSS only scans and obtains
design both civil and military projects in these areas.
data in one direction for six scan lines at a time. The
Aerial imagery acquisition and analysis is a valuable
TM acquires data at a resolution of approximately
tool for organizing and implementing a site selection
0.22 acres for seven spectral bands ranging from the
process at the early stages of construction planning.
blue part of the spectrum into the spectrum into the
b. Imagery analysis. The procedures developed
thermal infrared region (0.45 to 0.52 Fm, 0.52 to
to analyze terrain through the use of aerial imagery
0.60 Fm, 0.63 to 0.69 Fm, 0.76 to 0.90 Fm, 1.55
are, in effect, processes of terrain evaluation and
to 1.75 Fm, 2.08 to 2.35 Fm, and 10.4 to 12.5 Fm
elimination. Starting with a reconnaissance overview
at approximately 400 feet).
of a large area using satellite imagery, many areas
(3) In February 1986, the French launched the
can be eliminated from further consideration
Systeme Probatoir d'Observation de la Terre
because of topographic, drainage and access
(SPOT) satellite. This operational satellite is in a
problems. Conversely, potential sites can be
near-polar orbit, similar to the Landsat satellites.
identified. From these possibilities, the best potential
There are two High Resolution Visible (HRV)
sites can be selected for a more detailed, refined
sensors on SPOT. The instrument is also point-able,
analysis using stereoscopic aerial photography.
imaging 26 degrees on either side of nadir. There
Ultimately, a detailed data base of terrain
are two modes of instrument operation-the
information can be developed for a ground sampling
multispectral and panchromatic.
program and for the placement of specific
(4) The multispectral mode covers three spectral
structures.
regions-two in the visible (0.50 to 0.59 Fm, 0.61 to
0.68 Fm) and one in the near infrared (0.79 to 0.89
3-2. Regional analysis procedures using
Fm) at a resolution of approximately 0.1 acres. The
satellite imagery.
panchromatic (black and white) mode covers a wide
a. General. The military services of the United
band ranging from 0.51 to 0.73 Fm at a resolution
States have access to a vast array of satellite-
of approximately 0.025 acres. When the satellite is
acquired imagery through agencies within the
pointed at nadir, both HRVs image 37-mile wide
Department of Defense. However, the images pro-
areas. The satellite can point off to either side of
duced by these systems are classified, and the use or
nadir at 0.6-degree increments, up to 26 degrees on
potential use of these materials will not be addressed
either side of the orbital path. The satellite can thus
in this manual. Instead, the unclassified, easily
image any area within a 589-mile swath centered
obtainable imagery products of the NASA/Landsat
over the orbital path. This allows for acquisition of
satellite program, under the direction of the National
stereo imagery and for more revisit opportunities
Oceanic and Atmospheric Administration (NOAA)
over an area of interest. A maximum of six stereo-
and formerly under the United States Geological
pairs can also be obtained during the 26-day cycle.
Survey (USGS), will be discussed in this manual.
(5) The satellite data are acquired in a digital
(1) Digital data from the Landsat Multispectral
mode from the MSS, TM and HRV sensor systems
Scanner Subsystem (MSS) sensor have been
and can thus be analyzed by a computer. The
available for evaluation by the user community since
geometric accuracy of the data is to within one-half
July 1972. The MSS is a line-scanning device that
of a pixel. With this accuracy, the digital data from
obtains data for an area of 13,225 square miles (115
the sensor systems can be referenced to any
miles on a side) at a resolution of approximately 1.1
coordinate system.
acres. Data are obtained in four spectral bands --
b. Obtaining Landsat images. Reproductions of
two in the visible (0.5 to 0.6 Fm [micrometers =
Landsat imagery can be obtained from the Earth
microns] and 0.6 to 0.7 Fm) and two in the near
Observation Satellite Company (EOSAT), 4300
infrared (0.7 to 0.8 Fm and 0.8 to 1.1 Fm).
Forbes Blvd., Lanham, MD 20706. A computer
3-1
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