14. Gauthier, J.R.R. 
Canada 
THE PLANIMETRIC ADJUSTMENT OF VERY LARGE BLOCKS OF MODELS: 
ITS APPLICATION TO TOPOGRAPHICAL MAPPING IN CANADA 
Practical tests have confirmed that blocks of several thousand models can be adjusted with very few horizontal 
control points and that the accuracy of the results is sufficient to meet the specifications for the 1:50 000 map. 
Sixty per cent of Canada remains to be mapped at that scale. The unmapped regions include most of the Arctic 
Islands and large tracts of land east and west of Hudson Bay. None of the unmapped areas are settled; with 
few exceptions they are snow-covered more than 200 days in the year and they are all difficult of access. 
For Canada, the use of modern block adjustment methods will have the following results: 
S In the north, and in particular, the Arctic Islands, the existing horizontal control established for the 
1:250,000 maps will often be sufficient; 
= Control points established by the aerodist method with a density of approximately one point over 10,000 
km, will also be sufficient; 
- The accuracy of the aerotriangulation results will be superior to that obtained by the polynominal 
adjustment of strips. 
15. Gopalan, N. 
India 
ANALYTICAL STRIP ADJUSTMENT PROCEDURES 
The real problem during the course of strip adjustment by numerical interpolation procedures is the choice of 
the appropriate formulae, to suit the needs of the particular mapping problem. 
An attempt is made in this paper to compare the results of aerial triangulation strip adjustment procedures of 
a few strips, based on different transformations - linear, second degree conformal, second degree general 
polynomial - with a view to select the best suitable method. Redundant control has been made use of and the 
method of least squares applied. The transformations have also been carried out by using the minimum control 
and checking the accuracy by comparing the results with the available redundant control. Computer 
programmes have been evolved for the Honeywell 400 system. 
On analysing the results achieved, it is seen that the planimetric adjustment as obtained by linear 
transformation and subsequent second degree general transformation, using redundant control, by the method 
of least squares, is the most suitable, consistent with the demands of accuracy for plotting on medium 
topographic scales. The results of height adjustment obtained by second degree general polynomial 
transformation indicate general agreement with the results of semi-analytical methods, consistent with the 
demands of accuracy, at the same time economising on the control requirement. 
16. Hadem, I. 
Norway 
THE INFLUENCE OF HEIGHT DIFFERENCES ON 
THE ACCURACY OF AERIAL TRIANGULATION 
The paper deals with some theoretical investigations into the influence of height differences on the accuracy 
of aerial triangulation. Special attention is paid to the influence of errors in the inner orientation. 
The investigations are based on mathematical assumptions common in practical analytical photogrammetry 
when the coordinates of terrain points are estimated by a rigid bundle adjustment. 
Under further assumptions about numerical values of the accuracy of the inner orientation and the basic 
observations, numerical examples are given to demonstrate the influence of height differences on the accuracy 
of the estimated terrain coordinates. Different theoretical terrain forms are assumed. 
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