479
Conclusions
1. No general conclusions can be drawn from these investigations
since only four operators participated. Moreover, it must be empha
sized that the results refer tq the precision of the setting in a stereo
model. Throughout the experiment the same point was measured. The
importance of alcoholic intake for the relative and absolute orientation
and for the total photogrammetric procedure can hardly be judged from
this investigation.
2. The influence of alcohol varies from one operator to another
(see tables 3 and 4) and the setting precision in the stereomodel seems
not to be altered in any important amount (see table 4).
3. The investigations have given information about some additional
facts.
3.1 A play of the y-screw of A8 was discovered and adjusted.
3.2 A continuous displacement of some settings during the course of
a day could be explained by the unsymmetrical form of the signal. The
settings were successively altered.
3.3 In some cases a smaller training effect could be observed during
the first series, but also during the entire run of investigation 1.
3.4 Bartlett’s test has shown that an operator sometimes changes his
precision so much during a day that calculated standard deviations
cannot originate from the same theoretical population. If the measure
ments do not have the same precision, the assumptions underlying
variance analysis and error propagation are often not at hand. (Va
riance and regression analysis can be applied when the variance is a
known function of the independent variable in the analysis.)
4. It must be remembered that the setting precision, only, has been
investigated. It is possible to increase the precision by averaging (s ave r a ge
= s/ \/ n). The final accuracy of the photogrammetric procedure,
however, depends upon the quality of the image coordinates, the re
construction of bundles of rays, the relative and absolute orientation.
The precision of settings is in general so high that it has very limited
influence upon the final accuracy. The image quality seems to be the
limiting factor at present.
The precision of different method for Y-parallax elimination
Introduction
When the relative orientation of a stereomodel is performed in a
photogrammetric instrument, the y-parallaxes are eliminated in the
characteristic points of the model. The images and the marks can be
observed in different ways and in this investigation three methods
have been used: