2, For large scale mapping: 
- less control will be required than at present; 
= for the same flying height, positions established by photogrammetry will be 
more accurate or, alternatively, it will be possible to take photographs at 
higher altitude and obtain the same horizontal accuracy. 
Also in the immediate future, the development of simultaneous adjustments of photogrammetric data and 
auxiliary data (lake readings, APR, statoscope, etc.) will be implemented and completed, 
In the long term future, methods to automatically detect and reject erroneous data will be refined to increase 
the efficiency of the adjustment processes, The possibility and desirability of automating the whole aerotriangulation 
process will also be studied, 
COMMISSION IV 
Mapping From Photographs 
Reporter: Dr. J.M,. ZARZYCKI, Terra Surveys Limited, Ottawa 
Several new and significant developments took place in Canada during the period 1968 to 1972. The mapping of 
Canada has been accelerated, total photogrammetric capability increased in both government and private Sector, 
and new methods and instrumentations directed towards automation and simplification of the mapping process, 
have been developed, 
The basic topographic mapping of Canada is the responsibility of the Surveys and Mapping Branch of the 
Federal Ministry of Energy, Mines and Resources, Provincial survey departments are active in topographical 
mapping at scales larger that 1:25, 000 with the exception of the Province of British Columbia which participate 
with the Federal Government in the basic topographical mapping of the Province, 
Most of the provincial departments have not built up their own large photogrammetric facilities but have 
adopted the policy of contracting their mapping requirements to private photogrammetric companies, Mapping 
for municipalities and for a variety of engineering projects such as location and design of highways, railways, 
transmission lines, pipe lines, microwave communication routes and mining developments, are to a large 
extent, performed by Canadian photogrammetric companies, There are 20 such companies in Canada, 
The status of the basic topographical mapping of Canada is as follows. Mapping at 1:250, 000has been 
completed for the entire country, Approximately 4595 of Canada is mapped at a scale of 1:50,000, This 
percentage of completion represents 4, 300 published map sheets (1:50, 000) and an additional 1, 065 sheets 
(1:50, 000) compiled, but not published in final form. Mapping at the scale of 1:25, 000 is confined to urban 
centres, areas of higher population density and industrial concentration, At this scale 625 map sheets are 
published, and an additional 103 compiled but not yet published, 
For the vast areas of Northern Canada photo maps at 1:50, 000 and 1:25,000 are compiled, In flat areas 
the rectification method is employed; in others, orthophoto maps are prepared employing the Hobrough Gestalt 
Orthophoto System, During the reporting period 280 photo map sheets at 1:50, 000 and 34 sheets at 1:25, 000 were 
completed. Mrs. E.A, Fleming of the Surveys and Mapping Branch of the Federal Ministry of Energy, Mines 
and Resources, carried out experimental and research work in photo mapping at small scales which lead to the 
adoption of certain standards for this type of work, 
The Maritime provinces of New Brunswick, Nova Scotia and Prince Edward Island have embarked on a 
systematic mapping programme at scales of 1;1200, 1:2400, 1:4800, 1:5, 000 and 1:10, 000, in support of land 
registration and environmental data banks, 
The Province of Prince Edward Island which covers an area of 62,000 square kilometers, has adopted for 
its agricultural series, orthophoto maps at a scale of 1:5, 000 with 2 meter contours, The orthophotos are compiled 
employing the Hobrough orthophoto system from photographs at a scale of 1:20, 000, Approximately 859,5 of P. E. I. 
is already covered by the orthophoto maps. At the time of the Congress orthophoto mapping of the entire Island 
willbe completed, 
The ability of the Hobrough system to produce high quality orthophotos at the rate of approximately 3 per 
hour, made it possible to accomplish this task within a period of approximately one year, The excellent quality 
of these orthophotos, and the high efficiency of the Hobrough Gestalt System, are to a large extent, responsible 
for a wider acceptance of orthophotos in Canada. Hobrough has provided photogrammetry with a fully automated 
system for production of orthophotos, 
The development of orthophoto techniques at the National Research Council under the direction of Dr, Blachut 
took a different approach and is making use of stereo-orthophoto techniques developed by H, S. Collins, 
In the stereo-orthophoto approach, the orthophoto and its ''stereomate' are produced simultaneously in a 
single scanning process. The stereomate is a differentially rectified "second" photograph of the stereopair whereby 
each point is additionally shifted sideways by an amount, which is proportional to the elevation of the point over 
a reference plane, Whereas the orthophoto is a parallel and orthogonal projection of the stereomodel on the 
horizontal plane, the stereomate is a parallel and oblique projection of the model on the same plane, 
Both pictures (the orthophoto and the stereomate) can be viewed in a simple stereoscope. They represent 
a geometrically correct (within the limit of the orthophoto technique) spacial model of the terrain which can be