The Heritage Building Information Modelling System for non-destructive optical techniques: The case study of the restoration of a Marble sculpture on the façade of the Gesù Nuovo Church in Naples

The study focuses on an angel marble sculpture, placed on the central portal of the Gesù Nuovo church in Naples. The non-destructive and non-invasive optical techniques used were Active Thermography (AT), Colorimetry and 3D scanning. The measurements were carried out before and after the restoration of the marble sculpture, consisting in the consolidation of some disintegrated areas and in the removal of both black crusts and biodeteriogens, present in various areas of the sculpture. AT images provided a map of the structural inhomogeneities of the investigated areas, measuring the thermal response. 3D scanning, on the other hand, provided a 3D model of the entire sculpture and measured on a millimeter scale any structural variations due to the restoration. Lastly, colorimetry allowed a quantitative measurement relating to the color variation of the surface of the sculpture due the cleaning process. All this information was collected and entered into the HBIM (Heritage Building Information Modelling) system, which allowed a systematic cataloguing, providing a complete database on the made measurements.