10
this light through the zoom lens, rhomboid prism and dove
prism. The objective lens then images the parallel light
bundle to the emulsion on the drum surface by way of a
final 90° prism. Just above the output film is a mechan
ical mask or aperture which truncates the light to provide
the precise profile width. A shutter located on the
cassette is actuated by the print signal and automatically
closes when the model area has been exposed.
CONTROL S Y STEM
The motions of the printer described above are
controlled by a Bendix-272 computer, similar to that on
the AS-llB-ls, which also contains a high sneed paper
tape reader/punch. The control system is shown in Figure
2. The computer is a high speed, general purpose digital
computer with 16,384 words of core. The six servo commands
for the printer are generated by the computer based
upon model coordinate and orientation data. The coordinate
data is entered into the computer memory by the Ampex
mag tape unit while the orientation data is entered
by paper tape, teletype, or manually through the printer
control panel.
FUTURE CAPABILITIES
The present Off-Line Printer is being provided with
additional software to permit it to operate with terrain
data generated independently of the AS-11B-1. This can
be terrain data from a data bank, such as will be pro
vided under RADC's Advanced Cartographic System. This
same program will also provide the ability to transform
any photograph for which the camera and orientation
parameters are known, without the need for the AS-11B-1.
Future plans are to provide an orthographic trans
formation capability based upon limited terrain data.
This can consist of control derived through analytical
triangulation and the subsequent derivation of terrain
data by interpolation. Such an orthophoto product would
not be as precise as that derived from the present methods,
but it could meet limited requirements. In the case of
terrain of a gently rolling characteristic, this type of
product could be satisfactory for many applications.
