TECHNICAL NOTES
New Automatic Analytical Stereoplotter
U. V. HELAVA
A. E. WHITESIDE
C. W. MATHERLY
The AS-11B-1 automatic analytical stereoplotter performs automatic contouring
and profiling and provides automatic orientation assistance. It will also be equipped
with a time-shared electronic orthophoto attachment. The new automated system has
evolved from the AS-11A analytical stereoplotter and a developmental automated
stereoplotter and from automation modules designed to convert manually operated
AS-11A's to automated AS-11B systems. The AS-11B-1 is built around a new, power-
ful microcircuit computer designed by Bendix Research Laboratories. The power of
the new computer is used to improve orientation procedures, accuracy of mathe-
matical projection, computation speed for control functions, and operational versa-
tility. The optical-mechanical portion of the new instrument has 9- x 18-inch photo
carriages and includes a 1:4.5X zoom magnification.
INTRODUCTION
Much valuable experience has been gained in pre-
vious work on analytical stereoplotters, including
automated systems. This experience has suggested
several areas of improvement whereby such instru-
ments can more fully exploit the inherent potential
of the analytical stereoplotter concept.
The AS-11B-1 automated analytical stereoplotter*
incorporates all of the refinements and advances
made in the technology to date. The result is a com-
pact, highly flexible system which can be readily
adapted to many needs and applications. The follow-
ing sections describe major features of the AS-11B-1.
The principles of automatic operation and details of
the powerful new computer are described in an ac-
companying paper.Tt
OPTICAL-MECHANICAL EQUIPMENT
The AS-11B-1 viewer (Figure 1) is similar to those
used in earlier stereoplotters. This unit is basically a
stereocomparator with feedback servomechanisms. As
in the previous analytical plotters, the measuring
movements are split: the photograph moves in the y
direction and the optics in the x direction. Both are
independent, thus the calibration is easy and error
propagation simple. This construction, which is basi-
cally identical to earlier OMI-Bendix analytical plot-
ters,! has been found very good in practice; it is ac-
*The AS-11B-1 automatic analytical stereoplotter described herein
has been developed by Ottico Meccanica Italiana and Bendix for Rome
Air Development Center, U. S. Air Force, under Contract F30602-67-
C-0250.
TW. E. Chapelle et al, *Automation in Photogrammetric Compila-
tion."
BENDIX TECHNICAL JOURNAL SUMMER 1968
curate, stable, and favorable for servo control because
it distributes the inertial load evenly between the
carriages.
Some changes in detail and improvements have
been incorporated into the optical-mechanical equip-
ment. Most notable of these is the extension of the
format size up to 9 x 18 inches. In conjunction with
the redesign required by this change, the cathode-ray
tubes (CRT) of the-flying-spot scanning systems were
moved from side-vertical to rear-horizontal position.
This change improves the mechanical rigidity of the
optical parts of the scanner system.
The optical system has been redesigned, and af-
fords significantly improved performance of both the
scanner optics and the viewing system. Specifically,
the optical aperture of the scanner prime lens has
been increased to f/2.8, improving its resolution and
light transmission. Each viewing path is equipped
with a zoom system that covers a 1 to 4.5 range.
Thus, one set of eye-pieces can give a continuous
range of magnifications from 7X to 31.5X. The mag-
nification and Dove-prism image rotation of each
viewing path are individually computer controlled.
The normal system outputs are contour or profile
manuscripts automatically plotted on the coordinato-
graph. The range of magnification (or minification)
from the model scale to the plotting scale at the co-
ordinatograph is from O to 30. The precision of the
scale setting is 0.00001, and a different scale can be
used for each axis to accomplish exaggeration of
vertical scale when plotting profiles. The X-Y and up
and down positions of the stylus are controlled by
the computer. A coordinatograph control panel pro-
vides facilities for operator control of automatic plot-
ting operations. The coordinatograph could be used
