3D SURVEY TECHNOLOGIES TO DOCUMENT AND SUPPORT MICAELIC RUPESTRIAN ARCHITECTURE PRESERVATION. A CASE STUDY

Abstract. The paper presents the actions conducted for the case study of the Hermitage of San Michele a le Grottelle, in Padula (Italy) in the framework of the scientific collaboration between the Urban\Eco Interdepartmental Research Centre and the Diocese of Teggiano-Policastro focused on the development of specific programmes of preventive conservation for the rupestrian heritage dedicated to the micaelic cult. In this context, the hermitage hosts precious wall paintings which show signs of advancing non-uniform degradation: some frescoes are completely lost, unlike others that, despite being spatially adjacent, are still intact.

The investigation was oriented towards understanding the reasons for this condition and articulated in 4 main actions: (i) digitisation of the site through the use of optical sensors, in order to obtain a digital model of the geometric and colour components of the asset; (ii) collection of external environmental data for the statistical characterisation of the site conducted considering multiple parameters recorded as observations from several meteorological stations; (iii) manipulation of the reflectance data for the informative characterisation from a material point of view of the most degraded frescoes, correlated to the colour information as well as to the geological classification of the site; (iv) virtual simulation of the incidence of external environmental parameters on the surfaces of the 3D model of the site, inserted in the real territorial context, in order to determine the relationship of causality and relative weight between the boundary conditions and the degradation phenomena found in order to direct preventive conservation actions.