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.