Stratigraphic Excavation from the Field to the Computer: The Pompeii Prototipe

This work is included in the MURST - COFIN 1998 project under the responsibility of Prof. A. Carandini, University of Roma La Sapienza , Italy. The principal aim of this project is to develop a computer assisted method that could help in excavation management and support Stratigraphic Unit (SU) forms with as much information as possible. Our work intends to give a 3D visualisation of the excavation broken down into its elements: Stratigraphical Units. We want to complete the usual graphical documentation (plans and prospects) with a format showing surfaces and volumes of SUs excavated. We decided to test this prototype in a room of a Pompeian domus (Casa della Pescatrice) excavated in the year 2000 investigation by the University of Rome La Sapienza . As a SU was located, a picture was taken using a Nikon Reflex digital camera. Every shot also includes 4 small targets outside the SU in order to allow the orthorectification and joining with the 3D model. Secondly we surveyed the targets, the border and the internal surface of the SU using an ETS. The internal surface was surveyed at a rate of 100 points per square meter, but in the case of rugged surfaces we went down to 400 points per square meter. Only two persons (one using the ETS, the other keeping the prism) were engaged in these operations, carried out every time our colleagues decided to remove a SU. We do not believe this kind of work retards normal field operations and at the same time does not waste energy. Topographical data were successively transferred from the ETS memory card to a Personal Computer and then processed with the same software used for the management of the entire project: ESRI ArcView. We interpolated our points in order to make our surface as detailed as possible using ArcView 3D Analyst extension. The next step was to orthorectificate the images of every single SU and to insert them as themes in the same ArcView project. The resulting surface could be oriented as much as desiredon every one of the 3D axes, allowing unlimited different views of the same SU. We want to emphasise that any of these operations requires neither complicated Information Technology (IT) skills nor weeks spent in processing data: on the contrary, each of them can be carried out in a short time. Another important point is that the SU presented are in a format that bases itself on the data taken with a very accurate instrument that reduces enormously the errors resulting from manual plotting operations.