Three-Dimensional Analysis for the Documentation of the Restoration of an Earthquake-Damaged Triptych

The 3D digital reproduction of panel paintings is an efficient practice through which to document their state of conservation thanks to the ability to study artwork both at the microscopic level, visualising the craquelure and the detachments of pictorial layers, and at the macroscopic level, analysing support structures and their deformations. In recent years, research has focused on new methodologies to handle multiple 3D scans acquired over time and to achieve data fusion to obtain multi-resolution products. In this paper, we present the results of the acquisition of the central panel of an earthquake-damaged triptych using two different 3D techniques (close-range photogrammetry and structured light) before and after its restoration to carry out a multi-temporal analysis of the conservation status and document the effects of the restoration. Furthermore, we performed laser scanning micro-profilometry on a small area of the painting to study the artist’s technique and identify previous restorations. Finally, we merged the two 3D datasets (obtained by structured-light projection and micro-profilometry) to produce a multi-resolution 3D model with the aim of increasing the accuracy and readability of the final product.