4.4 Without discussing further details - for instance in 
small blocks the effects of additional camera orientation 
data deteriorate slightly, /13/ - it can be summarized that 
the utilization of navigation data for aerial triangulation 
is highly effective and economic. Even poor precision of 
auxiliary data is sufficient to reduce ground control for 
small scale- and medium scale mapping to the minimum of a 
few points only. One can conclude that experimental in- 
vestigations with auxiliary data are highly desirable. 
Their use in joint blockadjustment looks extremely promising. 
On the other hand it is essential that navigation systems 
become inexpensive enough for regular application in photo- 
grammetry. 
If navigation data reach very high relative precision, as it 
is anticipated, their importance will still increase more. 
They will then be able to influence high precision aerial 
triangulation for large scale application, still with mini- 
mum control. Thus, the importance of the development cannot 
be overestimated. It will be a final step in making aerial 
triangulation the universal, economic and flexible method 
for providing orientation of aerial photographs for almost 
any application. 
3. NAVIGATION DATA APPLIED WITHOUT AERIAL-TRIANGULATION 
5.1 Notwithstanding the great importance of aerial triangu- 
lation and the anticipated further development concerning 
joint adjustment with auxiliary data, it must be recalled 
that aerial triangulation has always been a method of indi- 
rectly determing external orientation elements of aerial 
photographs by using ground control points. This method .is 
only of interest, in principle, as long as no other method. 
| of determining orientation elements is feasible. The anticipa- 
ted high precision of navigation data, however, may change 
the situation fundamentally. Therefore, we should consider 
the possibility that aerial triangulation may become obsolete 
eventually. 
It is obvious that original navigation data, which would have 
to comprehend position- and attitude data, require calibra- 
tion and post-processing before they could be used for direct 
setting of image orientation elements in rectifiers, analyti- 
cal orthoprojectors or analytical plotters. Also the problem 
of interior orientation will have to be investigated. There 
are many conceivable possibilities, depending on the re- 
quired accuracy. 
5.2 Some general considerations show that the requirements 
for small scale mapping and for photo-mapping are not neces- 
sarily very demanding, especially with regard to planimetry. 
If position data are directly imposed for camera stations 
their errors are directly superimposed onto the bundles of 
rays. Standard errors of 1 or 2 m are directly sufficient for 
planimetry mapping or photo-mapping at scales 1:10 000 or 
smaller. 
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