Most errors in the orientation elements thus hardly exceeded mean errors which are 
customary in mutual orientation. Only the lateral tilt errors were relatively substantial, 
e. g. the w-error in adjacent models amounted to — 5° and + 6°. 
The errors in the nadir points are comparatively small, however they can reach sizes 
which have unfavorable repercussions on the strip radial triangulation. Irregularities 
in their sign have a particularly troublesome effect because they compromise the 
overall quality of the strip radial triangulation. 
Above all, however, the discontinuities in the lateral transition control points are 
dangerous. 
The discontinuities along the X-direction are small and, therefore, practically devoid 
of significance. Along the Y-axis it can be somewhat bigger. The maximum error of 
this type, in the Y-direction, amounts to — 5 m;it jumps to + 3:6 m in the adjacent 
model. 
The discontinuities along Z are most dangerous, because they cause substantial errors 
on the outer edges, e. g. altitude discontinuities of + 12 m and — 6 m appear next to 
each other. 
Striking is also the permanent change of plus or minus signs, particularly where dis- 
continuities are due to the lateral parallaxes. One often can observe in field work, that 
the “base inside’’ and “base out” discontinuities change their plus and minus signs. 
This phenomenon is mostly ascribed to the autograph error. However, it is probable 
that such opposing discontinuities for neighboring models are caused by film shrin- 
kage in the first place. 
The scale error fluctuates irregularly from model to model, too, and does so in a rela- 
tively marked manner. To be sure, it causes no very great discontinuities, but they 
are already noticeable as coordinate errors in the transition points. 
Practice shows that considerable errors do not necessarily occur in each model; how- 
ever, after some models, irregular changes will appear again and again, and thereby 
destroy the evenness of the error surfaces, which is needed for accurate triangulation. 
But a few pictures with substantial emulsion shrinkage are enough to destroy the 
evenness of the strip and compromise the precision of the transition points. 
Therefore, the experiments show clearly that no accurate and reliable strip radial 
triangulation can be performed in using film and that plates are to be used for all such 
work. 
Furthermore, it is an established fact that no film exists at present having shrinkage 
properties which are satisfactory as compared with those of glass plates. 
Printed in Switzerland