252
5. THE HIGH PRECISION TOPOGRAPHIC
CONTROL
To evaluate the altimetric mouvements of the
foundations and to analyse the altimetric
deformations between the ground floor and the
first floor, an high precision levelling network as
been realised. 68 control poins have been
distributed along the two floors. The
measurements have been carried on using of a
Zeiss Nil level with invar rod.
To measure the altimetric movements of the cover
have been decided to use an high precision
theodolite. An high precision 3D network has been
measured inside the palace-hall, composed by 5
control points. These points have been later
connected to the levelling network.
From these monuments five control points, placed
on the central internal arc of the cover have been
measured only with angular observations. The
points on the arc have been materialised using 5
white nails fired on the wood using an expert
marksman of the Padua police department. This
was the only way to place the reference mark on
the internal cover of the Palace ! Unfortunately
one these reference points after few days felt
down on the floor of the hall.
The four reference points have been measured
several times always with excellent results coming
from the least squares adjustment of the
measurements. The accuracy of the altimetric
determination of these points was always of the
order of 0.2-0.3 mm.
The total station used for these measurements
was the well experienced and well known Wild
T2000. This was the only method found to analyse
the altimetric movements of the internal wooden
structure of the palace.
Infact it was not possible to install any other
instruments on the internal structure of the cover
for the fact that it wasn’t possible to reach the
wood cover carrying from inside the palace.
6. FINAL REMARKS
The experience here described is a new expample
of integration betweem up to date automatic
control technology and a classic topographic
approach.
The experience of years in historical buildings
controls have permitted to found new ways to the
solution of some difficult control problems. The
control of Palazzo della Ragione can be assumed
as a valid expample of the need of the growth of a
measuring culture as often Prof. Cunietti have
teachen.
It isn’t enough to be good topographic surveyors
or good technicians (in the sence of people that
know well the surveying or meauring methods). It
Is important, when approaching a new measuring
problem, not trying to apply a well known standard
measuring approach but to study the problem, to
understand its originality and in this way to find the
best way to approach it, considering all the
conditions and all the particulars that at a first look
remain hidden.
It is the object of our study that contains the
answer, the way to obtain the best analysis of its
behaviour, and these answer must meet the
creativity and experience of the engineers and
technicians. When this happens new solutions and
new applications of old and new technologies are
found and enrich the common knowledge.
REFERENCES
[1] Brumana R., Crippa B., Vassena G., 1990:
"Analytical treatment and description of the
altimetric check of the St. Marcus' Basilica in
Venice", in Int. Archives of photogrammetry and
remote sensing, Commission V, ISPRS, Zurich.
[2] Brumana R., Monti C., Vassena G., 1991:
"Basilica di San Marco a Venezia: Analisi
dell'andamento altimetrico del pavimento litico-
musivo e metodologie di rappresentazione", in
Bollettino della Sifet, Milano, n. 2, 1991.
[3] Brumana R., Vassena G., 1992: St. Marcus'
Basilica in Venice: Analysis of digital images
projection. In: Int. Archives of photogrammetry
and remote sensing, Commission V, ISPRS,
Washington.
[4] Giussani A., Vassena G., 1992: Progetto e
simulazione della rete topografica di controllo dello
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[5] Monti C., Vassena G. : "Geometrie survey and
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the effectiveness of repair and strengthening of
historic masonry structures, Milano, 18-22 ottobre
1993.
[6] Giussani A., Vassena G. : “San Carlo Basilica
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