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INTRO |
2D
photogrammetric survey 
In
the present program of activities for interventions on the cultural
heritage, now decidedly oriented for goods preservation, the
photogrammetric survey is an irremissible tool for documentation,
measure and documentation... |
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PHOTO-PLAN |
Photo-plan
of the flooring 
When
we say "photoplane of the flooring" we mean a mosaic of
several digital photos each of which, through the use control points
directly measured on the object with topographic instruments, is
transformed in a metrically correct image... |
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USED-TECHNIQUE |
Definition
of the used technique 
Given a photo (i.e. a central
projection) in which is represented a well visible flat element, it is
possible to carry out a transformation (the so called
"rectification") in order to bring the flat surface from its
original perspective position to the orthogonal projection... |
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THEORETICAL
PRINCIPLES |
| Theoretical principles
The transformation on
which this process is based (improperly called rectification) it
defined in geometry as "photogrammetric restitution with
homography application". Homography is a transformation between
two flat spaces and it is ruled by eight parameters... |
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INSTRUM.
DESCRIPTION |
| Instrumentation description
The list of the main equipment and
instruments used for the photoplane production are the following... |
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PROJECT
OF THE SURVEY |
| Progetto del rilievo
La pianificazione del lavoro ha
previsto la realizzazione di circa 70 riprese per la copertura totale
delle aree di interesse, (che ammontano a circa 2150mq)... |
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CALCULATION
SCHEME |
Scheme of
the calculation of survey parameters 
Per
la determinazione dell'angolo di campo della fotocamera e quindi della
porzione di superficie che si puň coprire con una singola ripresa si
č operato come di seguito descritto. |
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SCAFFOLDING
DESIGN |
Scaffolding
design 
The
project of the scaffoldings have been very complicate since the wide
field to be covered and the considerable heights to be reached, it
made necessary the realisation of scaffoldings encumbering and out of
industrial standards. |
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ON
FIELD OPERATION |
| On field operation
Topographic survey of control points -
Assembling of the scaffoldings - Photogrammetric shots |
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PROCESSING |
| Processing
...After this sessions of
data preparing, it was possible to start with the rectification process
using the ARCHIS software, a package developed by Siscam which, starting
from control points co-ordinates, it is able to operate an homographic
transformation on the original images... |
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SURVEY
RESULTS |
| Survey results
The photogrammetric survey realised
with the digital photoplanes technique, is, without any doubts, a
basic and irreplaceable means for the documentation of marble tarsias
decorations of the Siena Cathedral flooring... |
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DELIVERED
MATERIALS |
| Delivered materials
The delivered materials are only
digital images and vector data recorded on cd rom that, when
necessary, can be plotted at the wanted scale (although the best
representation is at 1:50 – 1:25 scales)... |
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