] surfaces, a 
ion free dome 
yretic surface, 
its, regularly 
fact might be 
n as "border 
utside, led us 
ture occured. 
the lack of 
addition, the 
the ivan and 
  
The photographic coverage was arranged in a non-stereoscopic 
way. Due to the particular shape of the monument, and the 
available room around it, the stereo-taking would be much more 
difficult. The very particular pattern of the ceramic tiles helped in 
finding suitable control points. Again the plotting was performed 
by PhOX photogrammetric System. It resulted only in a digital 
output, being the 3d co-ordinates and their accuracy list. We 
estimate the accuracy in the order of few (one-two) centimetres. 
The evaluated points were 651. Again the plotting resulted only 
in a digital output. All the images were regarded as non metric 
images. 
This work allowed us to appreciate the deviations of the main 
meridian rib and the trend of the centres of the circumferences 
passing through the mean dome. The radius of the circular 
parallel of the cylindric drum varies from 7.03m at the base to 
7.15m on the top, 4.12m being the elevation difference. At the 
base all the dome points, regularly distributed, fall “inside” the 
interpolated rib. This fact may be due to the interpolation method 
used. There is an area of the dome surface where the points 
measured fall outside the mean cylinder. This fact is surely due to 
deformation. The plane co-ordinates of the centre of the base ring 
(X=63.086; Y=33.649, Z=25302), interpolated as a 
circumference, almost coincide with those of the top point of the 
dome (X=63.142; Y=33.620; Z=37.40). The difference in 
elevation is 12.10 m. The thickness of the dome wall is 
decreasing: from 0.84m at the base, to 0.35 of the top (we do not 
take into account the decreasing thickness of the ribs). 
4.CONCLUSIONS 
The study of damages and deformations of domes arc usually 
complicated for their surface and their location in the 
monumental complexes. This work shows that digital 
photogrammetry is an ideal tool to record every information. 
The speed up and the completeness of a larger set of points in the 
survey and the ideal geometrical configuration (the operator is at 
the centre of a sphere: ie. spatial irradiation) represent a real 
change with respect to previous applications. 
The disadvantages arising in the case of the domes considered as 
“difficult” geometrical shapes, become advantages in the spatial 
irradiation technique (all the points are detectable). The large 
number of the measured points profitably substitute the lack of 
iperdetermination. 
The integration of geodetic and photogrammetric techniques 
enabled the monitoring of the structural disruptions. 
The monitoring relies on the comparison of the present geometric 
state of the building with the ideal geometric shape of the design 
(symmetry, lack of discontinuity, flatness, verticality of planes 
and lines, sweep of overlapped domes, constant thickness of the 
walls). 
There are no doubts that the fact of getting an exact rendering of 
the apparent envelope will allow us to georeference the 
information gathered by means of the prospecting described 
above. 
The whole geometric data obtained in the continuous form were 
used as a bases for the digital reconstruction and simulation in 
3D CAD. 
  
Fig 5 The 3D CAD reconstruction of the double dome 
505