(2) Computer - The photo-position computations are performed 
by the AS-11 computer at a rate of 100 solutions per second, These 
computations and other real-time functions are performed by a portion 
of the computer referred to as the incremental section. This computer 
section is basically a digital differential analyzer, but it provides 
a number of special features to accommodate the particular accuracy 
and speed requirements of the analytical stereoplotter. Associated 
with the incremental section are high-speed interfaces which accept 
input commands from the operator's handwheels and footwheel and pro- 
vides output signals to control the viewer servos. 
The computer also contains a whole-number section, which has the 
same basic structure and capabilities as those of a general-purpose 
computer. In the AS-11A system, the whole number section is used 
for such purposes as: 
a, Reading and Punching Tapes 
b, Decimal-to-bínary and binary-to-decimal conversions 6 e 
c. Interrogation and interpretation of viewer control-switch 
positions 
d. Calculation of orientation elements for relative and 
absolute orientation 
In the AS-11B/C system operation, the functions of the computer 
are expanded to include all computation and control operations required 
for automatic plotting. The additional real-time functions performed 
by the incremental section include: 
a. Clearing elevation error and y parallax 
b. Controlling scan shape to compensate for the effects 
of camera orientation, camera geometry, and terrain slope 
c. Controlling scan size to minimize elevation-measurement 
; 4 
error © © 
d. Generating plotting motions for contouring and profiling 
e. Controlling plotting speed to limit the dynamic error 
f. Generating scaled model-coordinate signals which drive 
the coordinatograph, printer, and form-line contour generator. 
The additional functions performed by the whole-number section 
include: 
a. Detecting plotting boundaries or contour closure and 
control of indexing to the next plotting line 
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