INTEGRATED SURVEY METHODS TO OBTAIN INTERPRETATIVE MODELS AIMED
AT CULTURAL HERITAGE CONSERVATION
G. Tucci\ V. Bonora 3 , A. Spanò 3
a Dept, of Scienze e Tecniche per i Processi di Insediamento, Politecnic of Turin,
Castello del Valentino, Viale Mattioli, 39 10125 Turin, Italy - grazia.tucci@polito.it
KEYWORDS: Cultural Heritage Documentation, Surveying Methods, Digital Photogrammetry, Conservation.
ABSTRACT:
New tridimensional models can be useful for programs of conservation of cultural heritage. Models make easier the understanding and
the communication of particularly shaped architectonic structures, through a synthetic vision.
Our aim is to integrate different survey techniques (with their own accuracy) with computer graphics technologies, to create a dynamic
3D model representing phenomena and processes to be considered for preservation and restoration planning.
We show some experiences of survey on different periods structures, stressing the close relationship between survey techniques and
conservation problems:
Some buildings of “Borgo del Valentino” (Torino), a neomedioeval complex, with structural problems that make an accurate survey
necessary in order to restore it;
Povil Casaforte (Aosta), a medioeval building, in which metric survey has been a support for stratigraphic analysis of the complex
wall texture;
Villa Raggio (Asti), a 1900’s villa, where we used a digital direct photogrammetry (control points are only used to verify the
results).
The model obtained can combine two different needs. On the one hand it had to be accurate in order to guarantee the usability for
different technical purposes such as following the reconstruction projects or to schedule the routine maintenance and simulating technical
installation. On the other hand it had to be photorealistic and user-friendly for an easy and effective representation, useful in virtual
reality and other similar application.
1. INTRODUCTION
Every science needs to survey data end every scientific experiment
needs to organize them; this is true also in the investigation of old
buildings. As everyboby knows the survey has a gnoseological
and epistemological function and it doesn’t exhaust itself in
the knowledge of geometry and in the measurement operation.
Different geometries exist of the same object; we need to know
what kind of geometry and what kind of measures are enough to
describe, in exhaustive way, cultural heritage: this is a critical
operation. The next step is how to connect the specific measure
with a theory of observation: this involves methodological aspects.
Finally there are rapresentation aspects to evaluate how to describe
the same geometry. So, despite the accuracy raising and the new
techniques that allow us to acquire the greates amount of data as
possible, e.g. laser scanner technology, the survey assumes specific
connotates in function of different aims; the result is the inability
and uselessness of an objective and complete survey.
Therefore is required an act of conscientous and complex
evaluation, that is not reduced to a definition of the measurament,
but that is finalized having total knowledge of the object to be
explored, deciding on the information that is to be obtained by
means of observation.
The primacy of geometry and of the measure does not complete
the whole praxis of the survey.
There are other measurable components: materials, patologies,
colors, phisical and chimical phenomena in general, that need to
be rapresented on the geometric base.
Furthermore, these particular objects cannot be read and studied
applying a stereotype that locates symmetries, orders, hierarchies,
classification, repetition and series: cultural heritage needs a case
by case study, in accordance with the aims, rappresentation scale
and accuracy. The general criteria is that all the data must be
verifiable.
This implies the exact procedure and instrument description to
give objectivity to the entire work.
Interdisciplinary character of the acknowledgement process
orients the data acquisition procedures and in order to comply
with requirements of the specific case of study involves different
survey techniques and different measuring instruments.
New possibilities and new questions have been brought to light
using the ever increasing scientific and technological innovations
in the field of surveying, imaging and database management: for
instance, the introduction of laser scanner in architectonic and
archeological survey.
Pending the knowledge of the real usability of the laser scanner
data model with some work in progress, here are presented three
different metric approaches of heritage knowledge will show in
order to meet three different requirements: survey to describe
historic evolution and support restoration procedures; survey to
higthlight stratigraphy and materic consistence and rapid survey
in emergency cases.
2. DATA COLLECTION
For this purpose, instruments were used that would allow us
to have satisfactory results linking the advantages deriving
from the modem topographic method (having a very “detailed”
measurement programme of the form) to ones deriving from the
use of digital images (both for the photogrammetry and for the
qualitative characterization of the surface).