DIGITAL TECHNIQUES FOR MAP COMPILATION
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from a 7-track binary tape; six tracks contain
a pair of gray values and the seventh contains
an error-check digit. Each 7-bit code forms a
character, and 200 characters are stored on 1
inch of tape. A f-inch gap is placed between
two records. These data are then an input to
either DAMC programming system.
System Programs
SEQUENTIAL PROGRAMMING SYSTEM
One experimental program system consists
of five programs in the following sequence:
1. Resection-orientation
2. Rectification
3. Successive parallax correlation
4. Ortho-correction and contouring
5. Tic mark placement.
Figure 9 shows the information flow through
the sequential programming system.
Resection-Orientation Program
The Resection-Orientation program re
quires that every pair of stereo diapositives
be accompanied by a set of selected points
whose images on the photograph can be posi
tively identified with their corresponding ob
jects on the ground. These control points to
enable orienting the photographs with respect
to a ground survey. The relationship of stereo
map photographs to geodetic coordinates can
be determined by their ground-control in
formation, focal-length, and camera flying-
height. A WILD STK-1 stereocomparator is
used to measure coordinates of the ground-
images as well as the fiducials of the photo
graphic diapositives.
The ground control data and diapositive
measurements are converted to a punched
card format, which is used as the input to the
Resection-Orientation program. This pro
gram computes the tilt, swing, azimuth, and
nadir and related matrix of each photograph.
The coordinates of both the nadir and conju
gate nadir of each photograph are provided as
input to the scan process, in which both pho
tographs are scanned parallel to the flight line.
The program also puts out additional data
required as an input to the rectification pro
gram.
Rectification Program
The input to the rectification program con
sists of information supplied by the Resection-
Orientation program, measurements from
the stereocomparator, and photo data on two
Fig. 9. Simplified scan operation logic.