The stone of elephant, the survey of what was not surveyable

Giorgio VERDIANI / Federico PIRAS / Giovanni GUCCINI

(Facoltà di Architettura di Firenze, Italy)

Methodology/Approach: In the northern part of Sardinia, in Italy, there is a volcanic stone, it is very different from the huge number of all the other similar stones on that island because of three reasons: the natural forces worked on it giving to the stone a strange elephant shape; the ancient humans worked on it carving sepoltures for their deaths; in the contemporary age, after centuries when the monument was lost and forgotten, the works for a new road brought to light the stone which became one of the famous symbol of the Sardinia history.
Behind those things, this stone is a very interesting monument because it’s a mix of natural and architectonic events and it’s a very interesting case study for any real surveyor because it has the shape of an elephant and it’s a shape that is almost impossible to survey with traditional measuring solutions. In facts the stone is big enough, irregular enough, placed on a difficult enough terrain, to resist to any kind of low tech survey solution.
At the same time its strange and original shape give no guaranties about the health status of this monument: if a small part should get lost it will not be easy to verify the real damage and if a large damage should happen, how can be a restoration project planned? Will it be based on old pictures only? If the natural transformations will take centuries to cause transformations, the stone is now placed along a road and it’s freely accessible night and day without any kind of surveillance; so, what will happens in case of a car crash or in case of some tourist with an hammer and bad intentions?

Results: A complete survey of the shape of the stone was needed and a very accurate one. So our survey laboratory decide to go there to produce a meaningful case study, facing the unsurveyable stone with contemporary laserscan technology and with our research experience. The work takes place in the last November and required only two days to be completed, producing an accurate laserscan survey integrated by a topographical network build using a total station.
Here we present the first results of this work, where we define the real shape of this ancient monument in a specific moment, producing an useful archive which defines the definitive shape of the elephant stone at the beginning of the XXI Century, starting from now any transformation can be clearly verified as well any complete study can be developed starting from a very accurate three dimensional model.

Keywords: Sardinia, Italy, Digital survey, Laserscan, Modelling, ancient monument.