Computer-based method to digitally reconstruct axially symmetric fragmented heritage: the case of a medieval bell

The shape and tuning of bells provide archaeologists with valuable insights into their historical origins and casting methods. Unfortunately, the availability of fully preserved medieval and Renaissance bells is limited worldwide due to the remelting of many specimens following fractures, wear, or traumatic events such as earthquakes. The original geometry is therefore reconstructed by archaeologists by examining uncovered external mould during excavations. However, determining the symmetry axis and interpreting the profiles of small fragments is not trivial, and fragments are not always easily reassembled along their fracture surfaces. To solve this issue, this paper presents a computer-based method that enables the automated virtual reconstruction of ancient bells from their external mould fragments. The approach performs geometric and differential analysis of discrete models obtained from 3D scans of the fragments, facilitating the retrieval of a consistent 3D shape, thereby aiding in the preservation and understanding of historical relics.