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Fig. 1 - Sketch with the position of the nymphaea in the 
adjacents ’’House of the Small Fountain” (top) and 
“House of the Big Fountain” (bottom). 
2. TECHNIQUES APPLIED 
2.1 Photogrammetry 
The subject of the surveys (the nymphaea in Pompeii) is 
generally of a relative small size, with different kind of 
geometric characteristics, from a very simple structure to quite 
complex surfaces. 
For the photogrammetric image acquisition, and mainly due to 
handiness requirements, the choice has been for small and 
medium format semimetric cameras, but also a calibrated digital 
camera was adopted. In particular were used Leica R5 (24x36 
mm) and Fuji 690III (60x90 mm) film based cameras with 
reseau (equipped with wide angle and normal lenses) and Nikon 
D1 digital camera equipped with a wide angle lens. 
Normal and convergent photos were acquired, in order to apply 
classical stereoscopic plotting but also in some cases 
monoscopic non conventional techniques. A solution for a good 
stereoscopic coverage is represented by the use of the Cyclop 
system (Menci and Rinaudo, 2000). It is a single camera system 
(fig.2) that, simulating the use of a bi-camera, provides a 
specific software for mono- and stereo-restitution without 
requiring a topographic survey for ground control points 
determination. 
Fig. 2 - House of the Small Fountain: digital data acquisition 
using the Cyclop system. 
To provide a solution for the exterior orientation problem, three 
different approaches are applied: 
error ellipses of few millimetres, for the point determination 
and for the absolute orientation; 
- the scaling of the 3D model, derived from a relative 
orientation, by using distance measurements between well 
defined points; 
- the employing of the Cyclop system as a bi-camera, with a 
base value of 1.20, 0.90, 0.60 or 0.30 m depending on the 
size of the object (therefore adequate to the case in 
question). 
The orientation procedures (inner and exterior) are performed 
using a PC-based digital photogrammetric workstation 
(StereoView, Nikon Instruments) and also by an analytical 
stereoplotter (Digicart40, Siscam). 
Different products were until now produced and their use 
considered with archaeologists: 
- classical large scale three-dimensional vector restitution, 
either by analytical and digital stereoplotters; 
- monoscopic restitution of the main structure using digital 
photogrammetric programs, aided by automatic correlation 
and epipolar constraints for homologous point collimation; 
- design of profiles and sections; 
- digital surface model determination, either by manual 
operation and by automatic matching procedures; 
- digital rectified photos and orthophotos. 
Some examples are shown below, relative to surface modelling 
and derived orthophotos. Orthophotos, despite the difficulty of 
their application in architecture, provide a very powerful tool 
for restoration and documentation of monuments and materials; 
for their generation the capabilities of image matching 
procedures could be successfully exploited but they require 
appropriate a-posteriori manual editing (Baratin et al., 2000). 
Figure 3 shows the results of a comparison between manual and 
automatic (without editing) DSM generation, at a 10 cm grid 
spacing, for the Small Fountain nymphaeum; the surface was 
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- a conventional topographical survey of the GCPs, using 
special retro-reflective targets and high precision total 
stations (with normal EDM or reflectorless system): this 
solution provides the best results in terms of accuracy, with 
Fig. 3 - House of the Small Fountain: test for validation of 
automatic surface modelling (without editing) vs. 
manual DSM restitution on a simple mesh; values in m.