3 
Navigation (11) 
Image location 
Two important sources of image location errors have been thoroughly studied. (12),(13). 
A second-generation camera calibrator has now come into routine use. It provides efficient and accurate 
calibration to fields of view up to 120° and for any wavelength of light in the photographic region. Infrared 
calibration is becoming a routine procedure. 
Since there is still published concern about distortion due to camera port windows, it should be noted 
that windows to Canadian Category “A” requirements (5 seconds maximum deviation and not more than 
1 second variation in deviation over the whole window) continue to be readily provided. They are obtained 
by selection from plate glass made by the “Twin Ground” process. Both *4" and Vi" thicknesses have been used. 
Image quality 
A series of studies on image quality criteria have shown that simple low contrast resolution targets remain 
a practical means of testing, while MTF methods aid more detailed quantitative understanding of image 
formation. As a practical means of improving image quality, the need for better vibration isolation by camera 
mounts is still emphasized. (14),(15),(16),(17),(18). 
Two papers have dealt with the planning of photographic flights to ensure optimum image quality. (19),(20). 
Stereoscopy 
Stereoscopic aspects of two special photographic situations have been explored. (21),(22). 
COMMISSION II 
Theory, Methods and Instruments of Restitution 
Reporter: R. A. Stewart, Surveys and Mapping Branch, Department of Energy, Mines and Resources. 
Since the last Congress of the International Society for Photogrammetry in Lisbon in 1964, there has 
been continued development directed towards increased productivity of restitution instruments and methods 
in Canada. 
This development has encompassed a wide range of mapping scales and a diversified group of mapping 
organizations. The total range of the Canadian mapping effort has extended all the way from small scale 
1 /250,000 topographical maps to very large scale engineering maps. The federal government mapping effort is 
devoted principally to mass topographical coverage at scales of 1/50,000 and 1/25,000 and to many special 
larger scale projects for other government agencies. Several provincial government departments have added 
plotting instruments to their mapping divisions and they have shown noteworthy increases in their output of 
mapping. Sixteen commercial aerial survey firms, located in municipalities from the Atlantic to the Pacific 
Oceans, are engaged in one form or another of topographical and special purpose mapping. Canada’s National 
Research Council and at least three Canadian universities are conducting research and development work 
devoted to the improvement of restitution theory, methods and instruments. 
The widest range of instrumentation is used by the above mentioned organizations, varying from approxi 
mate solution stereometer type instruments to first-order universal plotters. While, at this date, practically all 
plotting is still being done by conventional, optical-mechanical projection instruments, it is proper to say that 
special instruments such as the various orthophoto producers are very soon going to make a tremendous 
impact in the field of restitution. Several governmental and commercial agencies have obtained orthophoto 
instruments and have progressed through the experimentation stages to day-by-day production. 
A new orthophoto system is being developed at the National Research Council of Canada. The main 
feature of the system is a novel orthophoto projector. Optical trains are added to an anaglyph-type plotter 
to facilitate direct viewing of the photographs. Thus, the instrument should be more convenient to operate, 
have a higher accuracy, and can be manufactured at a reasonable price. It will also be possible to use colour 
photographs as input. 
Several other components that can be added to the NRC orthophoto system are being developed: 
a) A contouring table is at an advanced stage of construction. Using this table, contours at cross sections 
of the terrain will be indicated. Computer techniques for automatic drawing of contour lines are being 
studied. 
b) A method for automatic hill-shading of the orthophoto maps has been developed. Automatic shading is 
possible by simple means that comprise a part of the system. 
c) A method has been developed for producing a modified orthophotograph which, when viewed stereo- 
scopically with an orthophotograph, creates a visual, three-dimensional impression of the terrain. Using 
these photographs, it is possible to accurately measure horizontal and vertical distances. 
For a great part of the restitution work to be done in the years to come, the trend will be from the present 
optical-mechanical projection instruments to the special orthophoto and automatic image-correlation instru 
ments. This will be true at all levels and at all types of mapping agencies, because of the special mapping 
requirements that exist in Canada. Because of the demand for coverage of a very great area, and the need for