Survey Methodologies for the Preservation of Cultural Heritage Sites

Abstract

In the Italian landscape there are a lot of Cultural Heritage sites, thirty seven of which are parts of the Unesco world heritage list. It means that frequently the disaster management has to deal with Cultural Heritage problems, such as preservation, safeguard, reconstruction, etc. Preserving Cultural Heritage for future generations is a duty; the importance of this task is proved by the attention which important international organizations have towards it (UNESCO, ICOMOS, CIPA).

It is possible to conceive two different risk typologies for Cultural Heritage runs. The first one, which could be called “ordinary” is the normal (inevitable?) decay due to age, so a low traumatic but continuous action; the second one refers to isolated impulsive events (earthquakes, fires, floods…). The correct approach to face these two kinds of risk is to get an accurate documentation of objects, buildings and sites. In fact, a whole knowledge of the object is able to lead both the common planned maintenance, and possible extraordinary restorations.

To correctly document an object, it would be important to have a 3D realistic model; its exploration could let the user achieve differently detailed data (both shape and radiometric), depending on the level of inquiry. Nowadays, the preferred way to achieve this goal passes through an integrate use of different survey technologies; in addiction a unique site reference system should be adopted. As a result of such choice, it would be possible to integrate all the surveys made at different epochs; moreover, alphanumeric information coming from different kind of studies could be associated to this precise geometric base in a GIS environment. This kind of tool is important for the management, registration, maintenance, and updating of the data; besides it makes consultation easier and offers the chance to join data for interdisciplinary analysis.

This article focuses on the integrate use of digital photogrammetry and LIDAR, which in recent years were involved in a deep technology progress; an interesting recently conceived tool, that can be easily created by adopting these two techniques, is the so called solid image. It lets the user access and manage 3D data through simply viewing a 2D monoscopic image; it adds correct 3D metric information to simple photos, so that information is much easier to be gained also by people who are not survey experts. The results of some test applications are exposed. The tests were carried out on some decoration stones in the Guarini Chapel, in Turin, where the Holy Shroud was held before the tragic fire in 1997. Another set of tests was carried out in cooperation with the Cultural Heritage Safeguard Office of Valle d’Aosta (northern region of Italy) and centred around the creation of a GIS for the management of the archaeological data on the walls of the important and well preserved medieval Castle of Graines.