10 
distance from any desired reference point. Coordinates can be read directly in 
display form. 
f. Automatic, Three-Stage Stereocomparator. The comparator is 
equipped with an on-line computer. Correction of coordinates for systematic 
errors, coordinate transformation and relative orientation is possible on-line; 
and a self-calibrating capability is built into the correlator. It is equipped with 
a stereo video monitoring and viewing system; a versatile control console ar 
rangement; and magnetic tape facility. The comparator, which is capable of 
automatic movement to predetermined photo points and an automatic preserva 
tion of stereoscopy capability, has the following additional characteristics: 
(1) Focal lengths are limited by programs only. 
(2) The optical magnification is variable zoom. 
(3) The X and Y coordinates on each of the three stages can be ob 
tained independently and can either be typed, punched, or recorded on magnetic 
tape. 
g. Graphic Input Device (BRL). A small, table-top-size instrument has 
been developed to digitize transparent or opaque photographic information as well 
as map, chart, and graph data for direct on-line entry to a digital computer. An 
electronic free stylus is used for tracing details in a fast and convenient manner-- 
the tracing surface is left clear and unobstructed. The device is self-contained, 
with a table-top light table housing mechanical X, Y carriages and the electronics 
equipped with incremental encoders; it is equipped with microelectronic modules; 
and utilizes a servo-driven stylus follower. Two units make up the device, namely, 
a coordinate measuring module and a control panel module; identification numbers 
and other digital data may be entered from the control panel. A display unit and 
a magnetic tape interface may be added,if desired. 
h. Hybrid Stereoplotter Modification Kit (BRL). A device has been devel 
oped to convert an analog stereo instrument into a hybrid instrument with a digital 
computer on-line. It consists of an input sensor, a real-time digital computer, 
as well as output servos to introduce correction to all three model coordinates 
and to the Y-parallax. The device increases the range of types of photographs 
that can be processed; it improves the accuracy of the stereo instrument by re 
moving cumulative systematic errors on an empirical basis; it provides easier 
and faster operations; it practically eliminates focal length restrictions; it has 
an input sensor (articulated arm with resolvers); and the device performs 
numerical orientation. 
i. Line Rectifier, Model LR-1 (BRL). A portable graphical line rectifier 
has been developed to utilize black-and-white photographs^ infrared line-scan 
records, or rectilinearized side-looking radar records; rectification of seg 
mented or partial photographs is possible as well. The device consists of three 
elements, namely, input module, electronic analog computer, and an output 
plotter. The characteristics of the device are: