11. Dorrer, E. 
Kurz, B. 
Canada 
STEREOPLOTTER INTERFACED WITH 
PROGRAMMABLE DESK CALCULATOR 
Design considerations and test applications of an on-line operated WANG 700 desk calculator interfaced with 
a WILD A-10 stereoplotter are discussed. Utilizing the input/output connector of the calculator, a special 
electronic interface using integrated TTL-circuits was built. Three separate up-down counters accept either 
square-wave or pulse output from three incremental shaft encoders. Strobed into a buffer in parallel, the pulse 
counts are read digitwise into the calculator. The input process can be initiated from either the keyboard 
manually or under program control periodically. 
The described modular arrangement features data acquisition speeds up to 60 spatial model points per second, 
flexible and simple programming and versatile output format. As a typical on-line data acquisition system, it 
simultaneously can digitize, store, display and process photogrammetric model coordinates and assist the 
operator in his decision-making capability. 
A variety of applications are discussed, such as on-line relative and absolute orientation, averaging repeated 
measurements and indicating current standard deviations, strip formation from independent models, 
correction, for earth curvature, on-line computations and display of scaled or transformed model coordinates, 
distances areas, or volumes. The ability to utilize the system as a programmable desk calculator, when not in 
use for data acquisition, makes it much more versatile and economically viable than a dedicated coordinate 
digitizer. 
12. Dorrer, E. 
Mostafa, K.H. 
Canada 
DIGITAL SIMULATION OF MECHANICAL STEREOPLOTTERS 
Due to design considerations, production tolerances, wear and tear, improper calibration or maladjustment, 
aging, external influences, etc., the accuracy and performance state of analog stereo-restitution instruments is 
often not at its optimum. The large number of spatial linkages and optical elements required for a technical 
reconstruction of the original bundles of rays, gives rise to the accumulation of small systematic errors that are 
difficult to describe. By making use of the principal flow of information in a stereoplotter, the kinematics of 
both the spatial linkage mechanisms from the model to the image and the geometric optics between measuring 
marks and image, however, can be formulated algebraically. The formulation itselt can be extended to a 
computer algorithm which is used as the basis of a digital simulation of the metric state of the stereoplotter. 
The principle of the mathematical representation of rotations and translations of spatial linkages are discussed, 
as well as the procedures employed in determining the dependent pair variables of a typical stereoplotter 
mechanism. By a simple ray tracing method applied to the essential optical elements, the process of 
photogrammetric static measurements can be simulated. Preliminary test results of the computer simulation 
program are presented, and its full potential is discussed by artificially introduced errors. The results are of 
interest to the efforts of sub-group 2 (Testing of Instruments of ISP’s Commission II). 
13. Doyle, F.J. 
United States 
INSTRUMENTS AND TECHNIQUES FOR CARTOGRAPHIC 
PROCESSING OF SPACE PHOTOGRAPHY 
The development of imaging sensors for space vehicles has been paralleled by the development of instruments 
and techniques for working with the records when they are returned to Earth. Image data from weather 
satellites, Earth-resource satellites, and planetary-exploration satellites are transmitted by television systems. 
Both analog and digital transmission are employed. The ground reconstruction equipments utilize kinescope 
recording, laser-beam image recording, and electron-beam recording with either analog or digital control. 
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