Laser scanning technologies for 2D and 3D imaging of decorated

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Laser scanning technologies for 2D and 3D imaging of decorated Powered By Docstoc

Fantoni Roberta1, Ferri De Collibus Mario1, Fornetti Giorgio1, Guarneri Massimiliano1, Ricci
Roberto1, Caneve Luisa1, Colao Francesco1, Fiorani Luca1, Palucci Antonio1, Ortiz-Calderon
Maria Pilar2

 ENEA Technical Unit for the development of applications of radiations, V. E. Fermi 45, 00044 Frascati (RM) Italy;
name.surname; 2Dpto Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide
Carretera de Utrera km 1, 41013 Sevilla, Spain; mport@upo.sp

Active remote sensing systems, generally known as lidars (laser radars), have recently found application
in high resolution scanning devices for mapping the actual preservation state of cultural heritage surfaces.
Conservators are interested both in structural damages (surface cracks and/or delaminations) and surface
deterioration from either physical or chemical agents, the latter due to surface reaction induced by
inorganic and organic pollution. Whatever is the damage, its precise location on the surface is a valuable
piece of information suitable to be visually conveyed by means of images, especially upon rendering with
real or false colors.
Laser scanning prototypes, formerly developed in remote vision and in metrology devices based on the
amplitude modulation technique, have been specialized for multispectral applications suitable              for
characterizing the large surfaces that are commonly found in cultural heritage monuments.
A three color imaging topologic radar (RGB-ITR, ENEA patent1), specifically developed for 3D imaging
of frescos, has successfully been utilized in chapels of churches dating back to the Renaissance period.
The high resolution (sub millimetric) 3D models reconstructed, allowed for hyper-realistic rendering of
colored features on frescos and for identification of surface irregularities - in terms of either in the color
layers or on the thickness of the underlying plaster - possibly related to otherwise undetectable damages
(scratches and detachments). Some preliminary yet promising results of tristimulus remote colorimetry
have also been obtained by means of the system.
An innovative LIF (laser induced fluorescence) line scanning system, capable of fast 2D monochromatic
image acquisition on up to 90 different spectral channels in the visible/UV range (ENEA patent 2) has
been developed to investigate the presence and the deterioration of consolidants, as well as the
occurrence of biodeterioration both on frescos and painted wood surfaces.
A further step towards the technological development of this system has been made by attempting to
integrate the two prototypes and test them in laboratory and field experiments,. The aim was to precisely
position surface damages identified by the LIF system, onto the corresponding RGB-ITR 3D high-
resolution model.
Examples of data collected during recent field trials on frescos, carried out by means of the RGB-ITR
(The Universal Judgment in Oratorio di S. Pietro Martire Rieti, “Amore and Pyche Lodge” in Rome) and
LIF scanning systems (S. Ana and S. Telmo in Sevilla; S. Jeronimo Granada, Marquena Dome), will be
reported and discussed, by assessing the significance of the results obtained for the conservation of
painted surfaces.

1 - G. Fornetti, L. Bartolini, M. Ferri de Collibus “Three dimensional Radar optical method and device based on three
    modulated RGB diode lasers for metrological and art work applications” Italian patent RM2006A000651
    submitted on 6.12.2006
2 - L. Caneve, F. Colao, L. Fiorani, A. Palucci “Portable laser radar system for remote surface diagnostics” Italian
    patent RM2010A000606 submitted on 17.11.2010.

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