- 3 - 
The Stereoplotter, Projection AP-14, is shown in Figure 1. It 
automatically searches for and traces contours and prints contour maps. 
An anaglyph plotter, to which has been added an electronic image- 
processing system, is the basic instrument. No computer is required; 
closed-loop analog servo systems perform all of the imagery sensing and 
contour tracing. 
A flying spot scanner tube, which can be moved up and down, re 
places the usual tracing table. The projectors are modified by adding a 
multiplier phototube in each projector head. The projector heads perform 
a dual function: each head projects light to form the anaglyph stereo 
model, and each head receives light from the flying spot scanner tube to 
process the imagery in each area of the diapositive. In this particular 
instrumentation, the two functions are not performed concurrently, though 
they can be by adding beam splitters to the modified projector head optics. 
Diapositives are placed in the projector heads, and the stereo 
model is oriented manually. The flying spot scanner tube screen is used 
as an oversized tracing table surface, with the flying spot being manually 
positioned by an operator-controlled joystick at various positions on the 
screen surface to orient the model. When the model is oriented, the multi 
plier phototubes are rotated into position in the projector heads; and auto 
matic searching and plotting of contours begin. 
At any elevation, the flying spot moves over the scanner tube 
surface searching for contours. When a contour is intercepted, the search 
mode is interrupted; the contour is automatically traced; and the search 
mode is resumed again. When all contours at an elevation are traced, a 
light flashes on an adjacent console, notifying an operator to raise the 
scanner tubes to the next elevation. 
A display tube is used for printout. Its beam moves in synchronism 
with the DC position of the scanner beam's center. The display tube beam 
is turned on automatically when the scanner beam is tracing a contour. 
Photographing the face of the display tube, as sequential contours are 
plotted, produces a contour map. 
Analog correlators process the electrical signals coming from each