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Figure 3.
Altimetric scheme of photogrammetric stations
As confirmed by the first survey, each order
should be considered as a separate element limited
by the plane of best fitting of the points
surveyed on the dripstone.
We used a Wild AC1 for the restitution and, since
our aim was to produce a mathematical model of the
Tower, we set up a data base into which we filed
the information to be processed.
After comparing the data obtained by plotting
monochrome and color photographs, we found that
the latter gave a more accurate collimation of the
points surveyed. After a careful analysis of
images available, six pairs of stereo-photograms
were chosen for plotting. These were numbers 1 and
12; 2 and 3; 3 and 4; 5 and 7; 8 and 9: 11 and 12
(Figure 2).
The remaining images will be used in a future
project that will focus on the details of the
Tower.
For the absolute orientation more than seven
control points on the Tower were used. The
orientation protocol shows that the maximum
residual was 0.4 centimeters.
The points surveyed and the way they were codified
is shown in Figure 5. The codes LV20 and LV21
refer to the points surveyed on the two edges of
the first order dripstone, while LV30 and LV31
relate to the second order, and so on.
Figure 4.
Pair of stereo-photograms