The survey of "eu-topic paces": integration of traditional survey with computer techniques to the case of S. Pietro Infine

The ancient village of San Pietro Infine, located near the border between the regions of Lazio, Molise and Campania, is representative of the situation of many other Italian cities, which for natural or anthropic events, such as earthquakes or wars, suffered abrupt devastations which turned them into "non-places". Remained as it was immediately after disruption, since a new town was built elsewhere, San Pietro Infine has become a place for memory (eu-topic), where the nature is progressively reclaiming its former space. The survey for these sites assumes the special function of revitalization, as it determines a simplified process of knowledge aimed at "reconstructing" at least in part the urban reality, now composed of elements so tightly interconnected to be not easily intelligible even to the eyes of expert visitors. The complexity of the area requires to integrate traditional survey methods with innovative, nowadays increasingly used, instrumentations such as laser scanning and to combine them within representation tools able to offer not only a graphic reconstruction of the detected area but, moreover, to create an interoperability of heterogeneous alphanumeric and iconographic data. This paper describes the procedure adopted for the survey of San Pietro Infine: starting from a visual inspection, reports have been created in the form of tables according to the format defined by the National Group for the Defense of Territory (GNDT); a system has been then structured to combine the collected information with a 3D graphical model built by elaborating the cloud of dots obtained with laser scanning. While the first phase has been particularly complex due to the difficulty of inspecting the destroyed buildings, the mapping of information did not present particular problems, since the cadastral pre-war maps were available; for the building of the 3D models an auxiliary procedure has been implemented, initially tested on geometrically simple elements of smaller dimensions, aimed at handling the cloud of points in the information system. The results of this latter procedure has revealed encouraging. The key objectives of the research is to build a complex model of systemic knowledge and provide the basis for a virtual reconstruction of the former city, even with the use of holograms. An additional goal of the research consists in defining an algorithm capable of reducing the number of dots in the cloud and to make the latter more manageable by the information system.