Reprinted from
PHOTOGRAMMETRIC ENGINEERING
March
1960
An Integrated Mapping System*
L. J- KOSOFSEY AND C. S. SPOONER,
Army Map Service, Washington, D. C.
ABSTRACT: À map compilation system in which the stereoscopic model is
covered completely by profile scanning is discussed. AU the necessary map in-
formation will be extracted during the single operation. The equipment which
is being built to investigate this system is described.
INTRODUCTION
HIS 1s primarily a progress report on an
"qs ion which has been carried on
at the Army Map Service for some three
years. Two previous reports have been pub-
lished in PHOTOGRAMMETRIC ENGINEERING.
The first (1) outlined the proposed system and
discussed the potential benefits which might
be expected from its adoption. The second
(2) described the results of several prelimi-
nary tests and plans for the construction of
experimental equipment with which to test
the main features of the system. At present
(October 1959) this equipment is being built,
with delivery expected late in the spring of
1960. This report will include a summary of
the essential elements of the system and a
functional description of the equipment being
built to investigate it. The oral presentation
will, it is hoped, include later information re-
sulting from the engineering tests of the
equipment.
1. SUMMARY OF SYSTEM
The Integrated Mapping System is an al-
ternative method for extracting map informa-
tion from the stereoscopic model. The con-
ventional method is characterized by a re-
peated search of the stereoscopic model, with
the pattern of each search governed by the
type of information being sought. The man
operating the stereoscopic plotter searches
the model for contour lines by defining a
series of horizontal planes, and tracing out
the intersection of each plane with the model's
surface. To plot drainage features, he
searches the entire model for changes in gray
tones which coincide with his expectations of
continuity and the tendency of water to run
downhill. He searches separately for roads,
buildings, etc, in accordance with other sets
of expectations. All these different operations,
in addition to much time-consuming drafts-
manship, are performed by the same person,
with the same instrument.
The essence of the Integrated Mapping
System is that it would require the instru-
ment operator to cover the entire stereoscopic
model just once, in a systematic manner. All
of the information necessary for the compila-
tion of a map would be extracted from the
model during that operation. The actual com-
pilation would be performed subsequently by
other people, away from the stereoplotting
equipment.
The manner of systematic coverage is by
profile scanning. The model volume is ex-
plored in a series of parallel vertical slices. The
measuring mark of the stereoplotting instru-
ment is kept in apparent contact with the
model surface as each slice is executed. The
measuring mark thus traces out profiles of
the model.
The method for extracting contour infor-
mation from this profile scanning operation is
indicated by Figure 1. The track of each pro-
file is interrupted when the elevation of the
profile corresponds to a multiple of the chosen
contour interval, and is resumed when the
next such elevation is reached. The compila-
tion of contour lines from such a plot is quite
straightforward; i.e., the ends of the line seg-
ments define the contour lines.
The information necessary -for compiling
all the planimetric features is extracted in the
form of an orthophotograph. An orthophoto-
graph is a replica of an aerial photograph
from which the image displacements due to
tilt and relief have been removed. It is pro-
duced by exposing a moving slit to one of the
projectors of a stereoplotting instrument
while the slit traverses the stereoscopic model
during profile scanning.
Reference (3) describes the early equipment
developed by the U. S. Geological Survey for
producing orthophotographs, and some of the
* This is a contribution to Commission IV of the International Congress, in September, at London,
England.
