Advanced information system for the investigation of deterioration of the floor in the Cathedral of Siena

The preservation and recovery of monuments are hotly debated topics in the field of cultural heritage conservation. In the early 1990's, our group in Siena started a study of the stone materials used in the architecture of Siena. The data were then processed by a GIS (Geographic Information System), which allows one to perform a series of interactive data analyses. An important example of the application of this methodology is the marble floor of the cathedral of Siena, consisting of 58 main scenes framed by decorations, for a total of 2500 in 2. The analysis involved: a petrographic study of the main lithotypes used in the scenes and of the various types of deterioration detected; realisation of a full digital photo-image and of digital models for the reliefs; identification of anomalies beneath the floor by means of geo-radar and geo-electric instruments; monitoring of thermohygrometric conditions; mapping of the 22 stone varieties employed, their state of preservation (33 types of deterioration) and the previous restoration interventions.