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Project 
SINUS 
THE CREATION OF THE DIGITAL MODELS FOR THE PROTECTION OF 
CULTURAL HERITAGE: THE BAPTISTERY OF CREMONA 
D. Conforti Andreoni *, L. Pinto ? 
? Codevintec Italiana srl, Via G. Labus 13 - 20147 Milano - Italy; e-mail: dario.conforti@codevintec.1t 
b Dip. LLA.R., Politecnico di Milano, p.zza L. da Vinci 32 — 20133 Milano — Italy; e-mail: livio.pinto@polimi.it 
Commission V, WG V/4 
KEY WORDS: Photogrammetry, Cultural Heritage, Integration, Laser scanning, Targets, Texture, Precision. 
ABSTRACT: 
In the Spring of 2003, it was realised a survey of the baptistery of Cremona (Italy) combining photogrammetric and laser scanner 
techniques. All the survey is composed by 22 photogrammetric images taken with a Nikon D100 18/2.8 digital camera and 14 scans 
collected by Optech's ILRIS-3D Laser Scanner. The geo-referencing was carried out with some natural and artificial targets displaced 
in the structure of the baptistery. The artificial targets used for this survey, were purposely projected, in order to get the best 
radiometric response and univocal geometrical definition; instead the natural target were surveyed in a traditional topographic way 
with a Total Station. The solid modelling of all the monument was made using a commercial software called PolyWorks; this 
software allows to align different scans with different reference systems and mapping some topographic information recording that 
on the 3D model. 
This method permits to get a good architectural representation (accuracy about a centimetre, calculated with some control points) and 
map the images onto the numerical model; thus the metrical quality of the survey remains unchanged without loosing the semantic 
settlement. 
1. INTRODUCTION 
The Spatial Information technologies offer interesting 
opportunities for the architectural survey both for the 
positioning survey, form, geometry and colour and for the 
surveyed representation. For the survey of the monumental 
structures, for which it is difficult to have the contact with the 
object either for the operating context or for its valuable 
features, two are the leading techniques: the photogrammetric 
survey and the laser scanner techniques. 
The first can be identifying with a classic technique even if in 
the last years it is visible a rapid methodological evolution of 
the photogrammetric close-range due to the coming of the 
digital camera. The classic scheme of acquisition of one or more 
stereo-couples, with normal shots at the object and consequent 
graphic restitution by stereo plotter, has nearly totally left space 
to much more flexible geometric schemes where are normal the 
shots even much convergent or at a different scale making 
practicable the images analysis only by monoscopic systems, 
having the advantage of using the wide reliability of the multi- 
Images systems. 
The laser scanner for land use is certainly, the most innovative 
and promising methodology in the architectural survey 
panorama. The capacity of acquiring hundreds or thousands 
points per second with high accuracy allows the knowledge of 
the surveyed up to the minimum particulars, supplying 
important results. For this reason, it is very important the use of 
a software of data processing equipped with a high number of 
base functionalities and big operating flexibility able to explore 
all the points and re-construct by modelling the surveyed 
surface and at the same time able to filter the data and create 
geometric primitives by fitting. 
Of great interest is the union of these two methodologies, the 
photogrammetric and the laser scanner ones. 
it unbalanced from the photogrammetric side it can supply 
orthophotos of accuracy thanks to the precise detail of the 
digital model produced by the laser or, if laser is the main 
instrument, it can supply texture mapping on architectural 
surfaces which introduce the creation of virtual realities. 
In order to investigate the potentialities of the two 
methodologies, with special attention to the metric accuracy and 
to the georeferentiation issues, in Spring 2003, on the occasion 
of a lab training of a Photogrammetric Course organised by 
Politecnico of Milan, it has been carried out the survey of 
Cremona Baptistery. 
The building (figure 1) is in the main square of Cremona, a 
place around which the civic, religious and economic core of 
the Medieval City was established. The Cathedral, The 
Torrazzo, The Baptistery, The Town Hall and the Loggia of 
Militi are one of the most striking monumental architectural 
complex of Italy: particularly the Baptistery on the southern 
side of the square was built in 1167 on octagonal map and is 
very similar to The Baptisteries of Florence and Parma. 
The building, once wholly in terracotta tiles, is articulated with 
buttresses and decorations and on the top there is a series of 
single and double lancet windows. The structure suffered, since 
1533, different interventions of renaissance which produced the 
exclusion of two of the three entrance doors. The one towards 
the square was left and later it was leant by a protirus on 
stilofori lions. 
The ancient loggia with bartisan was substituted by the existing 
coping gallery surmounted by a band of open circle windows. 
Finally the northern and western sides were covered in pink 
bricks. On the top a lantern dominates a wide roof at triangular 
gores which lines a big covering with eight sides. 
The interior, enlightened by the skylight, keeps its typical 
Romanesque spatiality. 
The survey has been carried out only outside concentrating the 
attention to the finalities of the metric survey. The 
photogrammetric taken have been planned and realised by the 
students of the Course, who have also taken care of the 
supporting point by a topographic survey. 
To complete the acquiring of the metric information it has been 
carried out a survey with laser scanner, as to achieve, together