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the instrument drums are to be used, the horizon camera data must be corrected 
for the influence of swing. 
4.3 Instrumental Procedure 
4.3.1 Using the B-8 or Other Instruments not having b z Movement 
The aerial triangulation is carried out by the independent pairs 
method, utilizing the data derived from the horizon camera and data given by the 
Doppler unit. The absolute orientation of the stereo model can be determined 
either by introducing the ^ and CO on the left plate holder or on the right 
plate holder of the B-8 plotter. The absolute orientation of the model will 
differ, depending on which is used, because of errors in relative orientation 
and errors in the horizon camera readings. 
The procedure finally adopted was this: the base distance given by 
Doppler navigator was introduced into the B-8 and the stereo model was oriented 
relatively; then the absolute value for ^ and CO was introduced in the B-8, 
first on the left and then on the right plate holders. The average values for 
and CO for the left photograph and for the right photograph were computed 
from both these determinations and were introduced into the plotting instrument 
to establish the absolute orientation of the stereo model. This method of 
determining absolute orientation minimizes the effect of inaccuracies in the 
relative orientation on the absolute orientation of the stereo model. The 
vertical datum was not carried by the stereo operator. The elevations of each 
pass point were read on an arbitrary vertical datum, and the models were 
connected mathematically during adjustment. After the absolute orientation of 
the model was determined, the operator pricked pass points required for stereo 
templates on stable plastic material. 
4.3.2 Using Instruments Equipped with b z and b y Movements 
When the instrument used for aerial triangulation is provided with 
a b z component, the procedure differs slightly. After introduction of the 
base distance given by Doppler navigator the y-parallax is removed with 
and by in their respective positions, then the 'f'* and CO derived from the