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This method of establishing horizontal 
control for photogrammetric mapping by 
Shoran is being used extensively in Canada 
and has been found satisfactory. Since 1952 
Canadian Aero Service and Spartan Air 
Services have established horizontal control 
by Shoran controlled aerial photography 
for an area of 500,000 square miles, 
The probable error in the position of 
nadir points using this method is — 14 
meters. It should be possible to improve 
this accuracy 20% to 30% by photo- 
grammetric methods similar to those de- 
scribed above. 
CONCLUSIONS: 
Shoran electronic survey methods pro- 
vide a very important aid in photogram- 
metric mapping. Particularly in mapping 
of inaccessible, large areas, Shoran has 
proved itself as the only economical and 
fast method of providing primary and 
secondary horizontal ground control. With- 
out the aid of Shoran it would be practical- 
ly impossible to map in a short period of 
time, large and mostly inaccessible areas, 
which, as the result of economic and poli- 
tical development, are now of valid interest 
and require maps for industrial and general 
planning. Shoran permits the establishment 
through trilateration of a primary net of 
high quality geodetic control. The relative 
14 
accuracy of distances measured by Shoran 
is 1 part in 60,000 (9). The first experi- 
ments with Hiran indicate a relative accur- 
acy of distance measuring as high as 1 
part in 113,000 (4). This exceeds by a 
large margin the accuracy achieved in pre- 
cise measuring of the geodetic base lines 
by conventional methods. For photogram- 
metric mapping, Shoran provides quickly 
and economically a dense net of horizontal 
control points with an accuracy which is 
satisfactory for mapping at 1/50,000 or 
smaller. The accuracy of the co-ordinates of 
nadir points determined by Shoran can 
be improved by applying photogrammetric 
techniques described in this paper, com- 
bined with a least square or graphical 
adjustment. 
In making a choice between Shoran or 
conventional surveying, one important 
point should be considered. A complete 
Shoran - geodetic - photogrammetric survey 
provides all horizontal control as well as 
all necessary photography and requires 
about the same length of time as conven- 
tional aerial photography. Thus a com- 
pletely controlled map is obtained in a 
single operation. 
Shoran is also practical and economical 
when used for control in seismic, magnetic 
and hydrographic surveys. 
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