- 107 - 
Figure 4. 3D edges extraxted from reflectance image. 
edge points has been measured and referred to the absolute 
system. After this, they were imported in the Autocad software, 
where, using the spline command, has been possible to build a 
three-dimensional wireframe model of the whole locals. This 
operation was conduced verifying the exact reconstrucion of the 
geometries as soon as comparing them with the drafts traced 
during the survey. The following step, always thtough Autocad 
software, was the construcion of the surfaces that have allowed 
to complete the reconstrucion from a vectorial point of view of 
the geometric model. The same procedure was followed for the 
external tambour side survey. 
The choice to use this method instead laser scanner survey is 
because the geometry of these architectures was very simple 
and easy to register by a classical topographic instrumentation. 
It would be useless to describe a planar surface with a cloud of 
milion points. Moreover traditional survey methods have also 
allowed to test the 3D model obtained from laser scanner. The 
inner profile of a decoration along the tambour has been 
surveyed by both methods. The profiles extracted from two 
survey technics (traditional with total station TPS 1103 and 
laser scanning) present a maximum gap equal to 2 cm. 
3. TRADITIONAL SURVEY 
4. LASER SCANNING AND TRADITIONAL SURVEY 
INTEGRATION 
Total station 
survey 
Two rooms 3D 
reconstrucion 
Total station 
survey 
External side 
of tambour 
reconstrucion 
Photogrammetric 
survey 
Two facades 
reconstrucion 
3.1 Photogrammetric Survey 
For large planar and regular surfaces, like the external two 
façades of the sacristy, photogrammetric single image 
techniques has been considered the best solution. It combines 
true scale geometric measurements with full image information 
under quite inexpensive instrumentation costs. To make this 
survey 22 images and 40 control points were needed. The 
software used during streightening and merging operations is 
Rollei MSR.The result obteined at the and of this elaboration 
has required a small intervention of photograph retouch to 
eliminate sudden changes of contrast or illumination between 
the images. 
For each position the scanner yelds a point cloud in the sensor 
coordinate system. The data sets of all the positions have to be 
orientated relatively to each other so that homologous points 
have the same coordinates. An absolute orientation can be 
performed if the coordinates of some object points are known. 
In this case on the scanned surface was present 10 signalised 
and measured target points. Their identification on reflecatnce 
images was very easy because the echos of the retro-reflective 
targets have much higher intensities than the surrounding area. 
In a second step other points were mesured to increase the data 
for scans orientation. These points were generally characteristic 
parts of the ornamentation. 
3.2 Geometric Survey 
Leica total station TPS 1103 was used during the geometry 
inquiry and the control points measuring for photogrammetric 
survey. 
This instrument has permitted to survey two little rooms 
enclosed to the sacristy. By this technic the coordinates of many 
Figure 5. View of two surveys in 3D STUDIO 
The 3D model of the sacristy was made from merging the 15 
scans in an indipendent coordinate system and then transformed 
using a 3D coordinate of target points into the absolute 
coordinate system.