3D Digital Microscopy for Characterizing Punchworks on Medieval Panel Paintings

This article is devoted to a novel application of the micro-3D modeling based on shape from focus. A 3D portable digital microscopeprototype has been used for the first time in order to analyze gold punchwork on medieval panel paintings. In general, the3D domain provides a more flexible and complete characterization of these decorative elements than traditional photographicdocumentation. Low-magnification 3D digital microscopy is well suited for analyzing morphologies, depths, and profiles of differentpunch marks. Here, we used these parameters for interpreting the punching process and recognizing sliding and bouncingeffects. The 3D reconstruction of the surface engraved also allowed identifying types of anomalies that could be useful as possibleauthentication markers. The advantages of the present approach with respect to the photographic documentation are of generalvalence and can be exploited in order to document, parameterize, and interpret a variety of engraving works on panel paintingsand metal artifacts.