426 
the reference values which in this case were obtained by the procedure 
in the autograph A8 must also be known. The accuracy of the auto 
graph values depends on several different factors among which are 
the interior orientation of photographs, the relative and absolute 
orientation of the model and the accuracy of the stereo-plotting machine 
the most remarkable. There is no information about the accuracy of 
the interior orientation, therefore such data must be estimated. The 
standard error of unit weight of the image coordinates is supposedly 
0.010 mm for a radius of 150 mm (19). In order to get an idea of the 
irregular errors in the image coordinates which are caused by film 
shrinkage, an adjustment of the measurements of the fiducial marks 
has been performed. Five parameters, namely two translations, one 
rotation, and two scale factors have been used in adjusting the discre 
pancies between the measured and the given values. The root mean 
square value of all the determinations of the standard errors of unit 
weights was 0.020 mm. According to the performed test measurements 
of the grid method the autograph A8 had a standard error of unit 
weight of 0.005 mm in the projector SGale. The regular errors of the 
instrument were all through smaller than their standard errors and 
have therefore been neglected in the computations. The standard error 
of unit weight of the relative orientation was determined by y-parallax 
measurements at 15 points. The following results are found: 
Strip 6010a M = 0.008 mm 
„ 6010b M = 0.010 „ 
„ 6011 M = 0.006 „ 
where M = the root mean square value of the standard errors of unit 
weights. 
M obtained by the parallax measurements has also been used in 
determining the accuracy of the absolute orientation. 
Fig 3. Locations and notations of 
elevation control points.