^
At International Business Machines (IBM)
an algorithm with polynomials was designed to
apply geometric corrections to high-resolution
images, such as those from the LANDSAT
(formerly ERTS) Return Beam Vidicon (Mar-
karian, et al, 1973). Shadow-casting techniques
applied in detecting and locating reseau marks
were adequate for geometric correction. The re-
sulting processed imagery did not show any of
the esthetic defects that can result from nearest-
neighbour assignment.
An analysis of the application of Automatic
Data Processing (ADP) techniques to digital
photographs was undertaken at Purdue Uni-
versity (Hoffer, Anuta, and Phillips, 1972). A
scanning microdensitometer was used to digiti-
ze both multiband and multiemulsion photo-
graphs (scale 1:120,000). The digital density
data were first spatially registered then analy-
zed by pattern recognition, with the following
conclusions :
1. Multiemulsion data are more difficult to
analyze than multiband.
2. Spatial register of multiband photographs
can be a problem.
g. Small-scale photographs (1:50,000 to
1:250,000) are more suitable for scanning and
ADP.
4. Computed corrections can be applied to
digitized photo data (e.g., vignetting).
5. While suitable for small-scale work and
for different types or conditions of cover, ADP
of digitized photographs must have close hu-
man supervision to avoid problems.
A study at the State of New York University,
Binghamton (Hsu, 1975) presented a multiva-
riate model for automatic pattern recognition
from day and night thermal IR densities. The
model is based on discriminatory functions de-
rived from density vectors. For mapping single
objects (houses, roads, water) point classification
is used in which the discriminant function is
derived from only two vectors. For scenes (resi-
dential areas, factories, croplands) area classifi-
cation is used in which the discriminant func-
tion is derived from ten parameters extracted
from a density surface constructed from densi-
tometer scanner data and computer graphics.
A report from the Earth Satellite Corpora-
tion (Van Roessel, 1972) explains a system
using a combined microdensitometer and mo-
nocomparator to measure x, y and density. The
x, y data are used in analytical photogramme-
try programs to get approximate positions for
selected terrain points. A terrain-surface func-
tion is estimated from these points by means
of hybrid orthogonal polynomials. With this
function and digital microdensitometer data,
image points are located with a predictive
pointmatching system, model coordinates com-
puted, and an improved terrain surface deter-
mined. The final output is a DTM and com-
puter-geaerated hypsographic map of the ter-
rain in the local coordinate system.
The Chevron Oil Company conducted a stu-
dy (Sabins 1974) of the needs for digital image
processing in oil exploration. The industry
now (1975) applies many remote-sensing tech-
niques but little or no digital processing. Sin-
ce the launching of LANDSAT, digital-proces-
sing potential increased because :
1. Worldwide imagery is available in digital
form.
2. The small scale, minimum geometric dis-
tortion, and uniform illumination of the ter-
rain are optimum for regional interpretation.
3. Digital-image
avallable for
tions
processing programs are
petroleum-exploration applica-
Before applying digital processing, however,
the oil industry would like to see data available
faster, a list of available processing programs
and their capabilities, and an estimate of the
cost per square mile.
A procedure for automatic mapping of strip-
mine operations from spacecraft data was deve-
loped at Bendix and Ohio State University
(Rogers, Reed, and Pettyjohn, 1974). Spectral
recognition is used as a basis for automatic tar-
get categorization and mapping. Hardware
units include a computer, magnetic tape unit,
line printer, card readers, teletype, moving-
window computer-refreshed color display, glow-
modulator film recorder, and a computer-con-
trolled Gerber plotter. It is suggested that strip-
ping and reclamation maps at scales of 1:24,000
and 1:250,000 can be produced from ERTS
imagery at one-tenth the cost of conventional
mapping.
Digital applications to side-looking radar
(SLAR) and panoramic images
A report from the Raytheon Company and
the Naval Research Laboratory (Bay, Bright,
and Kerr, 1975) describes an interactive digi-
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