X-ray shape-from-silhouette for three-dimensional modelling applied to ancient metallic handworks

The shape-from-silhouette algorithm has been applied to the reconstruction of the three-dimensional profile of metallic handworks from their X-ray absorption images. The acquisition technique is similar to tomography: several radiographies are taken all around the object, each of them is used to obtain the silhouette of the object at a given projection angle. Some reference points are placed on a structure that co-rotates with the object and are acquired on the X-ray images for calibration. The reconstruction algorithm gives finally the external three-dimensional appearance of the handwork. We present the analysis of a bronze pendant of 6th-7th centuries B.C. (Venetic area, Italy) completely hidden by corrosion products. The three-dimensional reconstruction shows that the pendant is a very elaborated piece, with two embraced figures that were completely invisible at the excavation. (C) 2013 Published by Elsevier Masson SAS.