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tograph must be known. In consequence the exterior orientation of each photograph must 
be determined. The best solution of this problem is to combine Shoran controlled photo 
graphs with aerial triangulation. This procedure being probably the most efficient and 
smoothest increases substantially the accuracy of nadir points. 
In order to increase the economy of this mapping procedure, if accuracy requirements 
permit, the Shoran controlled flights can be limited to the frame net only while covering 
the remaining areas with usual photographic strips tied into the primary network. 
The need to determine the exterior orientation of the aerial photographs and to con 
tour from stereograms requires a large number of known elevation points on the ground. 
In this regard the improvement of the radar profile technique opens new possibilities of 
mapping vast often inaccessible areas by reducing the unavoidable field work to a real 
minimum. Extensive statistical data from experimental and practical operations prove 
that by proper selection of ground points from the radar profile an accuracy of better 
than ± 3 m (as the mean square error) can be obtained over distances up to 100 to 500 
km between known elevation points 1 ). 
In the radar profile technique elevations of surfaces covered by the electromagnetic 
beam, and not point elevations, must be considered. Therefore, the accuracy of radar 
profiles in rugged terrain is limited. 
Very efficient method of airborne controlled arial triangulation developed recently 
is based on the use of radar profiles and of the infrared oblique photographs. This 
method gives an other possibility of mapping vast areas with field work limited to a 
minimum. 
Starting from a primary Shoran or any other network of fixed points the airborne 
controlled aerial triangulation can be carried out over distances of 300 km and larger 
with a high degree of accuracy. This extraordinary achievement was possible through the 
use of ground clearances (distances between aircraft and the ground) determined elec 
tronically in the process of aerial triangulation and using for the final adjustment pro 
file elevations. The adjustment of y-coordinates in the strip is based on the use of infrared 
oblique photographs made for of aft along the flight line. 
The characteristic feature of this method is that no direct contact with terrain is 
necessary to carry out the photographic operations. All the necessary control data are 
obtained from the photographic flight without external help. Just as in the case of Shoran 
controlled photographs, airborne controlled aerial triangulation can be limited to the 
primary strips only and this forms basis for the complete mapping operation. Experiments 
carried out on the distances up to 350 km in a flat area proved a planimetric accuracy 
better than ± 10 m (mean square error) with a mean square error in elevation of ± 
2.4 m. This error is reduced to ± 1.8 m for the points situated in a band of ± 1 km 
along the flight axis. 
No doubt, this very efficient method together with geodetic Shoran and Shoran con 
trolled photographs ought to bring a solution to the problem of small scale mapping of 
vast, undeveloped territories. We would like to stress once more the role played in this 
achievement by not only auxiliary electronic means but also the infrared oblique photo 
graphs. It seems, that the importance of this later technique has been simply overlooked 
so far. It should be also stressed, that the application of infrared oblique photographs to 
long distance aerial triangulation is only one of the possible applications of this type of 
photographs and further development in this field may be expected. 
Another simplification in the field of small scale mapping is the development of 
ground distance measuring devices. In particular, we have in our mind Bergstrand’s 
geodimeter which in future time will be produced in three different models: large, medium 
J ) These data refer to the flying heights up to 6,000 m over sea level. Radar profile 
flights at higher altitude are in an experimental stage and it would be too early to 
make any statements on the results achieved so far.