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illuminated dual display indicating X and Y axis positions are additional features. 
A relatively high accuracy is possible. A closely controlled environment is sug 
gested for the use of the comparator (70° Fir 1°F ambient temperature and 50% 
+ 5% relative humidity)--a self-controlled environmental system is furnished as 
an optional item. Digitized output can be made to card punch or other optional 
output devices. The comparator incorporates a self-contained leveling system. 
LINK GROUP, GENERAL PRECISION, INC. 
The Link Group, General Precision, Inc., Binghamton, New York, USA, 
has prepared three new items of equipment, namely, Automatic Point Transfer 
Instrument, High Resolution Orthophoto Output Table, and a Single Stage Measuring 
Device (Air Bearing). These are described below: 
a. The Automatic Point Transfer Instrument is a precision marking and 
measuring device wherein conjugate photographic image points are automatically 
or manually determined, the positions marked, and the coordinates read out on a 
typewriter and card punch. A card reader can be used as well to "read in" the 
coordinate point positions. The device consists of three comparator tables, a 
control console, associated electronic cabinets, and read-out and read-in equip 
ment. Additional characteristics are: 
(1) The three comparators can hold either glass plate diapositives, 
cut film, or film rolls; the function of the comparators is to support and trans 
port the diapositives with respect to their fixed photo scan system. Various 
image formats can be handled. A servosystem, linked with the correlator for 
static correlation and tracking purposes, is used to drive the comparator’s 
carriages. 
(2) The marking system is used to mark selected photo image points 
(including reseau marks and star images) on any or all three comparators. Mea 
suring marks consist of dots and circles. A requirement for high position accuracy 
of the measuring mark has been specified. A capability to transfer marked control 
points on small film chips to one or two photos which differ widely in scale is also 
inherent in the device. 
(3) The photo scan system (including optics) has the capability to 
adjust and/or correct for differences in photographic scale, tilt and rotation for 
both manual and automatic modes of operation; its main purpose is to examine 
the photographic images in a manner that will provide necessary data required 
by the correlators and the stereo viewer. The system will accommodate various 
types of photography up to medium degrees of tilt. Flying spot scanners, deflection 
circuitry, multiplier tubes, etc., are used to scan properly the photographic image 
as required by the overall logic of the system. Likewise, a variable demagnifi 
cation lens system and a raster shrinking and shaping capability is introduced to 
accommodate scale differences. 
(4) Images on the three comparators are correlated by a system 
which provides the necessary logic to control the servodrive systems. In the 
static mode the correlator provides coincidence of the conjugate image points