Photogrammetric survey and 3D model as experimental tool for mapping of polychrome marbles in artworks: the case of two Baroque altars in Bari (Italy)

This paper focuses on the use of the photogrammetric method to obtain 3D model of artworks for their characterisation and conservation. The high-resolution reproduction of a piece of art allows both the identification of constituent materials, decorative elements and detailed features and its digitalisation and enjoyment and then enhancement. In this study the approach was applied to the polychrome marble altars in the crypt of the St. Sabino's cathedral and in the St. Giacomo's church, both in Bari (Italy), significant evidences of virtuosity of Baroque sculptors and of use and reuse of precious Roman marbles combined with more recent and local stones. For this purpose, firstly, a three-dimensional model and high definition survey were performed by collection of numerous photographs and their processing using photogrammetric method and digital survey software; in addition, identification of Roman marbles and other decorative stones was carried out in terms of lithological classification, provenance locality, the historical period of employ. Results, obtained through an inexpensive, fast and complete survey, allowed to produce a high definition representation of the altars for a complete mapping of used material and decorative features and to guarantee their conservation, sharing and enhancement.