Integration of Non-Destructive Acoustic Imaging Investigation with Photogrammetric and Morphological Analysis to Study the "Graecia Vetus" in the Chigi Palace of Ariccia

Integrating complementary information from many available technologies is a question of growing interest among the Cultural Heritage community, due to the complexity of the cultural assets under study and of their contexts. Recently, this need has pushed the development of appropriate data fusion procedures for this sector, among which the authors wish to propose their approach for treating multi-source data from image-based methodologies, experimented with in a representative case study. The Chigi Palace of Ariccia hosted our investigation campaign on a precious monochrome painting by Giuseppe Cades (1788), the Graecia Vetus. The study encompasses a photogrammetric survey and two acoustic diagnostic methods, the innovative Frequency Resolved Acoustic Imaging technique and the more traditional Acoustic Tomography. The photogrammetric survey allows reconstruction of the surface morphology of the painting, generating a 3D Digital Elevation Model, while the acoustic methods detect the structural damage beneath the surface due to detachments and flaws, generating 2D images. The output of this heterogeneous datasets fusion is a multi-layer map, each layer representing a type of dataset that clearly shows how some deformations of the surface morphology appear correlated with the presence of sub-surface anomalies, wide air cavities and more superficial detachments revealed by the acoustic diagnostic methods. Beside the exam of the conservation state of the Graecia Vetus, the proposed procedure effectively guarantees access to the integrated information, offering the possibility to understand the correlation between the causes and the effects of the decay process, as well as the retrieval of the single analysis in order to deepen one specific aspect.