6 
GIUSEPPE I N G H I I, L E R I 
Then, the third point that we take into account for a correct evaluation of the 
angle O is the taking point common to the models ; this point, at a considerable di 
stance from the points A and B, allows a very precise determination of the longitu 
dinal tilt. 
In practice, as the equations i) and the following are solved simultaneously, 
all the three points 0, A and B influence with the same weight the determination 
of the three rotations <J>, g and a. 
Once the equations i) and the following are solved, we know the values of the 
7 absolute orientation parameters of the second model ; with these parameters, the 
instrumental coordinates of the taking point on the right and of the two points 
analogous to points A and B are transformed ; this operation is repeated for all the 
successive models that, in this way, are connected both in planimetry and altimetry. 
Of course, in order to execute only the instrumental connection, control points 
in the first model are not necessary ; the second model is connected by imposing 
that the instrumental coordinates of the taking point on the left and of the two 
points A and B are transformed into the instrumental coordinates of the correspon 
ding points in the first model ; in this way, we obtain that all the models are con 
nected with reference to the instrumental coordinates system of the first model. 
Afterwards, it is possible to compute an absolute orientation of the whole 
strip on three or more known points and, successively, to compute an adjustment 
if the number of control points in the strip is sufficient. 
Strip and instrument setting up. 
As regards to the strip setting up, it is necessary, first of all, to individuate 
the pass points, that is the points of type A and B of which we said in the prece 
ding paragraph. This can be solved either through a careful analysis of the possible 
pass points that are sketched, after observation at the stereoscope or through a 
pricking of two or more points in the triple overlapping zone of each photogram. 
In the experiments we executed and which we shall illustrate later on, we 
followed the procedure of the sketches. 
Afterwards, it is necessary to determine the instrumental coordinates of the 
taking points. In this connection, the operations are described with reference to the 
Stereosimplex III Santoni, we used in our experiments. 
First of all, a suitable value of the instrumental base is established that per 
mits the maximum size for all the models of the strip ; this value is imposed to the 
cameras moved in the b x direction ; generally the b x values of the two cameras 
are the same, but this is not strictly necessary. Now, moving the carriage, the left 
rod is made vertical by means of the level (see fig. 2) and the planimetric instru 
mental coordinates v s , y s of the left taking point are read ; then moving the carriage 
the right rod is placed in vertical position and the values x d , y A are read. 
Now, we have only to determine the instrumental Z coordinate of the taking 
points. For this purpose, it is sufficient to measure the difference in height between 
the taking points and the intersection point of the rods.