1) Aim of the research
2) State of the art
1) Aim of the research
First aim of the search is the reconstruction of the virtual shape of an archaeological find through the management, on CAD system, of information obtained from the analysis of available fragments. This objective demands the setting up of a methodology, supported by computer science systems, for the acquisition, by means of automatic machine of measure, of relative geometrical data to the lower surface and the upper wing surface of the elements of surface of fragments. With a limited number of measure points it is possible to obtain the definition, sufficiently near the truth, of the surface that envelops them. Moreover, it is possible to employ, beyond that the traditional techniques, also techniques of scansion with scanner 3d laser or television cameras in order to optimise the times or to improve the virtual reconstruction of the object of perfect shape.
A second aim, connected to the first one, is the development of a classification
system and coding of the characteristics of the fragment. That particularly
demands to considerate the geometric nature of the two surfaces, the inner and
the external one, and of the main characteristics of the thickness that, as
an example, could be its main value and its maximum variation percentage. These
data, joined to those of descriptive type that the experts of archaeology will
suggest to take in consideration, will be the base of the classification and
coding system by means of which, with an appropriate algorithm the rebuilding
of fragments pertaining to the same object or the same productive technology
could be operated. The resetting operation, in particular, could be made easier
from the comparison with virtual elements gathered from the analysis of intact
or already restored objects and inserted in the classification system in order
to act as guide elements of the selectioning algorithm.
The rebuilding of fragments could therefore be operated at first in virtual way, using the parametric capabilities of employed CAD system that will follow an algorithm of genetic type in order to define the shape that better draws near the external or inner surface of the object.
The third objective, in fact, coming out from the definition of geometry, consists
in the construction using Rapid Prototyping (RP) techniques, of the virtual
object. All that to reach the definition of the inner surface of the object
which functions as external surface to the supporting model of the real fragments
that will be rebuilt after the necessary cycles of analysis and synthesis to
obtain, with the best approximation, the shape of the report to restore.
The file relative to the digitised model of the approximate inner surface of the manufacture to reconstruct can in fact be directly transferred to the RP equipment. It is employed in order to generate the model in resin to employ as support surface of the fragments that on it will be fixed with suitable glues, before in temporary way and therefore, after the necessary replies, in definitive shape.
2) State of the art
present proposal is originated from the crescent interest that the archaeologists
recall in a generalised manner in relation to their valorisation like fundamental
economic resource of the Italian territory and in particular of the southern
region. In the southern territory, that corresponds in great part to that one
of the Magna Greece, in fact, There are the signs of the civilisations that
have marked the more flourishing periods of the history. It is thought of fundamental
importance to bring a methodological and technological contribution to the valorisation,
through the recovery, the classification and the restoration, of this huge patrimony.
The technologies, today available, whose employment is shown here, are in a
position to bring a substantial contribution to the irreplaceable and passionate
work of the archaeology experts. The present proposal must be considered a contribution
to the cause of archaeology in the spirit of the multidisciplinary co-operation
that is the only approach that concurs, in the diversity of the roles, the most
effective valorisation of the specific competencies.
job that the archaeologists carry on, at first previews the collection and the
classification of fragments recovered during the dig, and therefore it demands
the reassembly and the reconstruction of the original objects from which they
Sometimes there are very small fragments (also of the order of magnitude of ten millimetres) that, with a manual and laborious procedure are in first, cleaned up and classified for zone of recovery, thickness, colour, quality of the paste and therefore for shape. Subsequently it proceedes to the aggregation of the fragments that are judged pertaining to the same find and, therefore, they pass to the definition of the shape of the original object through the acknowledgement of the curving by means of the employment of opportune characteristic shapes and of the resemblance to already known archetypes. The experience, the sensibility and the acquaintances of the researchers engaged in a such kind of job produced permit to reconstruct an object destroyed many centuries before, replacing the numerous fragments. All the described operations are conducted manually. The acknowledgement of the shapes and the attribution of the qualitative parameters are only fruit of the acquaintance and the subjective experience of the operator.
if subsequently it has been done a certain progress because the phase of classification
and of acknowledgement of fragments, with the purpose to recompose the single
objects, has been managed, by means of an appropriate program, with the aid
of the computer, other systematic applications of the computer science technologies
are not still diffusely employed. After recent but episodic applications, of
the solid modelling and the rapid prototyping to the reconstruction or the duplication
of particular works of art, it comes the consideration that would be today possible
to co-ordinate and apply to all the available experiences and to obtain very
important results integrating, in an only procedure, a series of techniques
Great part of such acquaintances constitutes a cultural patrimony, within the disciplinary area of the Drawing and Methods of the Industrial Engineering.
present plan of search foresees, moreover, the use of multiple computer-aided
systems and therefore the necessity to guarantee the continuous transmission
of information. The management of reference protocols for data exchange is integrating
part of the present job in object.
The actual studies lead on the problematic dealing with data exchange between CAD systems, by means of neutral translators (IGES, STEP), have evidenced which problems are in the transfer of the surfaces constructed in different ambits of development (each characterised from a specific inner format of system) , to different ambits of use (virtual reality, rapid prototyping). A Correct data exchange of the surfaces demands a particular attention to the parameters of accuracy (that control the generation of geometry) and to the zones of connection between different "patches" of surfaces (presence of gap or overlapping).
For the individuation and the correction of eventual errors and inaccuracy of the geometry, object of a reconstruction or an operation of transfer, will be used CAD systems more advanced or " dedicated " to the management of the surfaces.