49 
The conclusion from this comparison is that there is no appreciable difference 
between the three methods as long as the flights are regular but that Inghilleri’s 
method is more sensitive to deviations from the normal case. 
Ten models of this artificial strip have been used to calculate the influence of 
errors in the plate-coordinates on the orientation-elements and on the model-coordinates. 
The result also gives some indication of the variation of the cofactors of these quantities 
in relation to camera-inclinations and terrain-forms. 
The influence of possible errors in the reconstruction of the interior orientation 
of the camera could also be evaluated. It was shown that this influence can be minimized 
by the relative and absolute orientation, and that as a consequence, the requirements 
for the observation of the fiducial marks in the stereo-comparator are less stringent 
than for the model points. If, as in this case, the relative orientation is computed from 
six points only, the residual T-parallaxes in the model are no practical criterion for 
a check on the reconstruction of the interior orientation. 
2. The connection of adjacent strips 
2.1. 
In analytical triangulation as in triangulation in analogue instruments, the 
precision of connections between adjacent strips depends mainly on the identification 
of common points. 
Where analytical triangulation is executed with monocular comparators, strip 
formation depends on the identification of corresponding points on subsequent photo 
graphs in the strip. For these reasons it is essential to know the properties of the various 
procedures used for this identification. The procedure that has been tested is the stereo 
scopic point-transfer using different systems of marking of points. 
These systems of point-transfer consist essentially of two parts, viz.: 
1. Setting a mark of some form on two homologous points in the stereoscopic image. 
2. Marking the position, so determined, permanently in the emulsion of the photographs. 
The first item is common to all stereoscopic observations, the second is an additional 
requirement in those cases where we have to mark points. 
To obtain an impression about the precision of stereoscopic transfer a test has 
been carried out with three different systems: 
1. Setting with a measuring mark consisting of small holes in transparent material and 
subsequently pricking points through these holes with a simple needle. 
2. The P. U. G. of Wild. 
3. The so called snap-markers of Zeiss.