4 
better methods of rapid revision to supply an ever increasing demand, the advent of fast, automatic restitution 
procedures is most opportune. At the present time, and for some years to come, restitution will continue to 
manifest itself in graphical and pictorial form. However, progress in numerical restitution is being followed 
with great interest with the view to implementing these procedures when they become more precise and 
economically feasible. 
COMMISSION III 
Aerial Triangulation 
Reporter: R. E. Moore, Surveys and Mapping Branch, Department of Energy, Mines and Resources. 
This report was compiled from replies to questionnaires sent to the Air Survey industry, universities, 
government mapping and research organizations. 
Instrumentation 
During the past four years, the number of first order analogue instruments for aerotriangulation has 
remained much the same even though the number of air survey companies in Canada has increased. During 
the same period there has been a marked increase in the number of first order plotting instruments that could 
be used for single model aerotriangulation. At the time of the last Congress, there were three stereocomparators 
in Canada and these were being used in research organizations to assist in the development of analytical pro 
cedures. During the past four years, a total of five stereocomparators were purchased by large mapping 
organizations, by research institutes and by universities. 
All aerotriangulation instruments have been fitted with appropriate coordinate readout systems to give 
clear text, paper tape or, punch cards. Point transfer devices such as the Wild PUG and the Zeiss point marker 
are being widely used in aerotriangulation procedures, particularly when adjustments are made on the elec 
tronic computer. 
The majority of replies indicated a strong preference for a monocomparator, as it is estimated that the 
initial cost will be low, the operational cost will be normal, and the accuracy that could be obtained will be 
greater than that of analogue systems. It seems that there is a market in Canada for an accurate, reliable mono 
comparator, one that would not have a high initial cost and could therefore be left idle part of the time. 
One of the most attractive solutions for aerotriangulation in the future, mentioned in a number of replies, 
is the use of first order plotting instruments for single model aerotriangulation. Computer programs are now 
being developed to adjust this type of aerotriangulation. Considering the large number of first order plotting 
instruments available, single model aerotriangulation may well be the trend for the future. 
Data acquisition procedures 
The bulk of the coordinates produced in Canada are 3-dimensional and are obtained from first order 
analogue aerotriangulation instruments. Although there are a good number of first order plotting instruments 
in Canada, few of these are being used to produce 3-dimensional coordinates for aerotriangulation. Two 
dimensional coordinates for analytical air triangulation are now being produced on stereo comparators to a 
limited degree. 
The National Research Council has developed a monocomparator that has created a good deal of interest 
in Canada because of its potential economy, speed and accuracy. However, this instrument as yet has not 
been manufactured for sale on the market. 
A erotriangulation adjustment 
In 1964, most mapping organizations depended heavily upon graphical strip adjustment and block adjust 
ment systems such as stereo templates and there was a minimum amount of adjustment on the electronic 
computer. At present, the reverse is true. Stereo templates and graphical strip adjustments are being used to a 
very limited extent in mapping organizations. Block adjustments on computers have replaced these systems. 
Numerical adjustment methods 
In Canada, numerical strip and block adjustments developed by Schut of NRC have received national 
acceptance. In these systems, the adjustments of strips for horizontal and vertical control are performed sepa 
rately. Universities and some large government organizations have developed their own adjustment procedures, 
but for the most part, industry and government are using systems designed by Schut. These numerical methods 
have improved the accuracy and the reliability of the product, and reduced the overall cost. 
Computers 
The earlier programs developed by Schut were coded for the IBM 1620. These programs and adjustments 
have proved to be very reliable over a considerable period of time and are still in use. With the introduction of 
3-dimensional block adjustment and the use of analytical procedures, there is now a definite trend to use larger 
computers such as the IBM 360 systems. There is a growing interest in the direct solution of block adjustment, 
starting with analytical measurements and adjusting simultaneously data for large blocks both vertically and 
horizontally. Also, there is an increasing effort directed toward incorporating the adjustment parameters of