THE RADAR PROFILE AND ITS APPLICATION TO PHOTOGRAMMETRIC MAPPING 
by 
T, d. Blachut 
National Research Council of Canada 
Ottawa 
In Canada, during the past few years, a technique has 
been developed which not only opens up new possibilities in the 
field of photogrammetry but which may also have considerable 
influence on the future development of photogrammetric methods, 
particularly as they relate to mapping at small and intermediate 
scales. This so-called airborne profile recorder method was first 
conceived during the war but its development and its adaptation to 
photogrammetric requirements is the result of work carried out 
since the last International Congress in 1948. Some of the details 
of the method still require clarification but the actual method 
itself has already been established, the equipment has survived 
the rigors of early experiments, and the results of numerous tests 
are now available; moreover, considerable practical experience has 
been gained from the application of radar profiles to various 
cartographic problems encountered during the mapping of some 
1.500,000 square kilometers (about 600,000 square miles). The 
results obtained are based mainly on Canadian terrain but data on 
some parts of Central and South America and Alaska are also availabl : 
We will not discuss here the problems which are purely 
instrumental in character since they belong more properly to the 
field of electronics, but we would like to describe the basic 
principles of the method itself, the procedure followed and the 
results obtained, in the belief that they will hold the greatest 
interest for this assembly. 
Before enlarging on this theme, however, I would like to 
express my very sincere thanks to the two organizations, the 
Aeronautical Charts Division of the Canadian Department of Mines 
and Technical Surveys and the Photographic Survey Corporation of 
Toronto, whose names are closely allied with the airborne profile 
recorder method, and particularly to Mr. 5- Jowitt and Mr. D. A: 
MacFadyen, for their kind co-operation in connection with this 
review. 
In principle, the method is very simple. An aircraft 
carrying special radar equipment and a positioning camera flies 
over the terrain. Microwave impulses are continuously directed 
downward and the optical axis of the camera is aligned with the 
microwave beam. The aircraft should fly at a uniform altitude 
using the isobaric surface as a reference surface. After being 
reflected from the earth's surface; the electro-magnetic impulses 
are recorded, and since the speed at which the electro-magnetic 
waves are propagated is known and the time which elapses between 
the moment of emission of the impulse and its return is measured,