8 
measurements, performed in static mode with a 
sampling time of 15 sec in continuous acquisition for 
two days, double frequency receivers were used. 
Data processing has been performed by means of 
BERNESE vers.4.0 scientific software. In fig.4 are 
shown the rms values at 1c level of the WGS84 
geographic coordinates of 25 vertices of the network. 
During 1998, about 80 photographic support points 
have been measured, by means of the GPS technique, 
for a digital photogrammetry application along the NE 
rim of the phlegrean caldera (Camaldoli hill). Also if a 
future use of these points for monitoring purposes is not 
planned, as they will not be remeasured, the 
coordinates set thus calculated could be utilized, 
besides the generation of DTM (Digital Terrain Models) 
in aerophotogrammetric applications, also for SAR 
Interferometric applications (phase unwrapping). 
Fig.4 RMS values of the WGS84 geographic 
coordinates of the Phlegrean Fields network at 1c level 
2.4 Sar Interferometry (INSAR) 
Both the classical topographic techniques and the GPS 
technique, also if they are able to allow a tridimensional 
positioning of one point with up to under centimeter 
precisions, suffer from the disadvantage of providing 
informations related to a discrete number of points; so, 
in this case, is useful to utilize, together with these 
techniques, others which are able to allow an areal 
estimation of the deformation field. 
The INSAR is well suited for this purpose, providing 
also a ground deformations control during the time by 
means of the application of the technique in differential 
mode (DINSAR). 
Besides, the results obtained by spirit leveling and GPS 
measurements could both be used for a validation of 
those ones obtained by means of INSAR, and for a 
support in the interferometric SAR data processing 
(phase unwrapping): the innovative aspects of this 
research project are therefore directed to an integration 
of INSAR data with data obtained by means of other 
topographic techniques, classical or satellite 
techniques. 
The area selected for satellite (ERS1/2) INSAR data 
processing is a rectangle of about 40x30 km centred on 
the Phlegrean Fields. The images have been processed 
by means of PCI software on UNIX platform. 
In this initial phase it has been decided to generate two 
interferograms (with a pixel dimension of 40x40 m), the 
first one with August 1995/August 1996 images (fig.5) 
and the second one with November 1995/February 
1997 images. 
The possibility to get, for the first interferogram, a 
baseline short enough (about 11 m), has allowed to 
avoid the application of the interferometric technique in 
differential mode. In this case, the phase contribution of 
the topography to the interferometric signal, can be 
considered negligible, thus the resulting information of 
fig.5 can be evaluated only as a deformation signal. 
Fig.5 August 1995/August 1996 Interferogram of the Phlegrean Fields: in the figure it is possible to note just more then 
one fringe 
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Fig.6 Gee