AN INTEGRATED MAPPING SYSTEM
the minus X direction along the same profile
at the maximum speed (20 millimeters per
second). The Z-drive automatically moves
the measuring mark so that the entire first
profile is retraced. The operator watches the
measuring mark to see that it actually re-
mains in contact with the ground. The profile
is re-recorded on the temporary tape.
If the operator is satisfied with the first
profile, he pushes a “RECORD” button when
the left end is reached. The profile is retraced
from left to right once again at maximum
speed, guided by replay of the temporary
tape. This time the television pickup tube is
in the place of the measuring mark, and the
contour plot and orthophotograph are being
printed. The first profile is also being recorded
on the permanent tape and re-recorded on the
temporary tape.
When the right end of the first profile is
reached this time, the measuring mark re-
places the television pickup tube, and the
V-drive indexes to the position of the second
profile.
This time, as the measuring mark is driven
to the left along the second profile, it retraces
the first profile, guided by replay of the tem-
porary tape. That is, it would retrace the
first profile if the operator let it. But he uses
his Z-drive servo control to over-ride the
memory guidance so that the measuring
mark actually traces out the second profile.
That is the essence of memory-aided profiling.
[t is based on the expectation that successive
closely spaced profiles differ from each other
by small amounts, and that an operator can
readily see the small differences apparent
during a retrace. The speed of the retrace is at
all times under the control of the operator.
The second profile as it is actually traced is
recorded on the temporary tape.
[f the operator is satisfied that he was suc-
cessful in using his override control to trace
the correct second profile, he pushes his
“RECORD” button when the left end is
reached. As before, this causes all recordings
associated with the second profile to be made
while the profile is being traced from left to
right at maximum speed.
The sequence is followed all through the
model. Whenever the measuring mark is
moving to the left, it is retracing the previous
profile and is subject to override by the opera-
tor. The permanent tape and the other re-
cordings are made as the current profile is
being retraced to the right.
Whenever the operator wishes to verify or
correct a profile before recording it, he pushes
a “NO RECORD” button, which causes the cur-
rent profile to be retraced, subject to his over-
ride, as often as necessary. The permanent
recordings, however, must be made in the
plus X direction.
There is considerable flexibility in the fre-
quency with which orthophotographs and
permanent recordings are made. It is possible,
for example, to record on the contour-plot
every profile, on the orthophotograph every
other profile (after adjusting the masked
width of the cathode ray tube) and on the
permanent tape every fourth profile.
The purpose of such flexibility is to permit
tests which will establish optimal precedures
for the future. The tests will also have to de-
termine the speed and accuracy attainable
with the equipment in various types of ter-
rain.
A few words remain to be said about the
properties of the permanent tape profile
record. It is a more complete record of the
shape of the earth's surface than a contour
map can be, and it is in a form which can be
hand.ed by modern automatic data process-
ing methods. It is, in fact, the raw material
for a digital terrain library. A few of the con-
jectural uses for such a library are:
a. Recompilation of a map at a different
contour interval, without additional photo-
grammetric work.
b. Revision of contours based on ground-
control acquired after the original stereo-
plotting project.
c. Automatic computation of earthwork in
the design of highways and other engineering
structures.
d. If a convenient method can be devised
for storing planimetric information in digital
form in conjunction with the profile record, a
completely digital map library becomes possi-
ble. The storage of map information in this
form would put it all within reach of auto-
matic processing methods.
It will be possible for the first time to at-
tack such problems after the planned tests
of the Integrated Mapping System have pro-
duced a body of recorded profiles.
REFERENCES
1. Spooner, C. S., Dossi, S. W., and Misulia, M. G.,
"Let's Go Over the Hill," PHOTOGRAMMETRIC
ENGINEERING, XXIII, 5, December 1957.
Kosofsky, L. J., “Investigation of an Integrated
Mapping System,” PHOTOGRAMMETRIC ENGI-
NEERING, XXIV, 3, June 1958.
3. Bean, Russell K., “The Development of the
Orthophotoscope,” PHOTOGRAMMETRIC ENGI-
NEERING, Vol. XXI, 4 (September 1955).
Le)