reduced to maintain accuracy in areas of difficult photographic 
or terrain conditions. The orthophotographs and formline contours 
are compiled as the stereomodel is automatically scanned in the 
profiling mode. The compilation scale factor is continuously 
variable from 0.2 to 5.0, and the profile step-over interval can 
be as large as 5.0 millimeters. When using the high contrast 
USAF resolution targets, the limiting resolution of the image 
transfer system is 60-line-pairs per millimeter at a compilation 
scale factor of unity. The formline contour chart, while 
generally less accurate than the conventional charts compiled 
on the coordinatograph, is advantageous in some situations since 
it is compiled with no additional expenditure of time. In 
medium scale chart compilation, it is anticipated that the 
orthophoto and formline contour chart will be used for an off- 
line edit of the automatic graphical contour data. The ortho- 
photo will also be used for planimetric intensification. 
Examples of the three outputs-orthophoto, formline chart, 
and automated contours - of the AS-11B/C for a model near Ft. 
Sill, Okla., are shown in Figures 8, 9 and 10. Input to the 
AS-11B/C was six inch focal length frame photography at a scale 
of 1:48,000. Gaps occurring in the primary orthophoto compila- 
tion due to loss of correlation, have been filled using the 
automatic fill-in mode. Bends in the reseau lines are indicative 
of the displacement of imagery to compensate for relief error. 
The formline chart, Figure 9, was produced simultaneously with 
the orthophoto. The dark lines represent index contours, narrow 
lines are indicative of steep slopes whereas wide lines mean flat 
or gently sloping terrain. The contour output, Figure 10, was 
compiled separately. The breaks in the contours represent 
areas wherein the computer detected a loss of correlation below 
the threshold value designated by the operator. Continuation of 
the line after a short break indicates that the automatic search 
routine was successful in relocating the correct level and 
automatic plotting was continued. 
61. Current Status: The AS-11B/C is located at the USAF 
Aeronautical Chart and Information Center, St.Louis, Mo. The 
system currently in existence is a prototype instrument. It 
is being operated on a three shift, 24 hours a day, five days 
a week basis. The work being done on each shift represents 
research to some degree. One eight hour shift is devoted to 
pure research for future developmental purposes. The other two 
shifts which are assigned projects represent the production 
operations this type of instrument would ultimately have to 
achieve. Operator training is taking place and operating 
procedures are being developed. 
A typical USAF compilation is being performed to establish 
time/machine characteristics. 
The operations have been progressing in this manner since 
29 September 1966. 
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