SOME EXPERIMENTS OF SEMIANALYTICAL TRIANGULATION 
5 
The scale factor X can be computed by the formula : 
5) A = 
\ S (x 2 + y 2 + z 2 ) ) 
Then, after the computation of the orientation parameters, the instrumental 
coordinates of any point of the model can be transformed into ground coordinates ; 
particularly, also the known instrumental coordinates of the taking points can be 
transformed. In this way, we shall know the absolute position of the taking points 
Chand 0 2 of the first model. Let us now consider the two (or more) points A' and B' 
of the ground model common with the second model. Then, we have in the first model 
three points, O', A and B, whose ground coordinates are known (see fig. i.) As we 
said, in the second model we know, for the same three points, the instrumental 
coordinates ; moreover, the points 0, A and B are in a convenient position for an 
accurate computation of the absolute orientation. 
In fact, the only points A and B would allow an approximated planimetrie 
connection between the models (computation of the azimuthal rotation cr) and also 
the approximated computation of the transversal tilt p ; if in the ground zone com 
mon to the two models, a third points exists, the computation of the longitudinal 
tilt is very inaccurate, in consequence of the small dimension of this zone, if the 
normal longitudinal overlap is used.