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Pilot, Miniutti, Auditore 
We began by surveying the principal network in order to determine the vertices of orientation that delineate the area of Torcello. To 
carry out this frame, we decided to operate by setting up standings on three points of the GPS IGM 95 network in Saint Mark’s 
Square in Venice, in Roncade and in Fossalta di Piave. 
The 1000, 2000, and 3000 points constitute the primary vertices of the network located in the surrounding area of the island. The 
length of the bases to determine required varying acquisition times, depending on the survey methods and the level of precision to be 
obtained. 
In the network of Torcello, the bases take on dimensions of between 10 and 20 km; so, given the use of double frequency receivers, 
the sessions were set at intervals of about one hour each. 
Fig.l: The Photoplan of the Island of Torcello 
Subsequently, we proceeded with survey of a detailed network, using the system defined by the three principal vertices as datum 
(1000,2000,3000), in a static mode. 
The acquisition time in this phase was significantly reduced thanks to the diagram of the network realised; once the three receivers 
were positioned in the vertices of the principal network, each new point was surveyed from the inverse intersection to the vertices of 
known co-ordinates. In this way, the baseline between the vertices of detail were not considered, but exclusively those with the 
principal vertices. 
The need to identify the position of the points where it was impossible to make standings using the traditional methods, for instance, 
on the poles in the lagoon, led us to do part of the measurements in the RTK (Real Time Kinematic) method. 
GPS measurements done with this method are constituted by a base station (master) located in correspondence to a vertex of the 
fundamental network and a mobile antenna (rover) located, in this case, on board a boat to reach the points to be measured.