Fakers and Mold-Makers: The Use of Structured Light Scanning to Detect Forgeries of Pre-Hispanic Effigies from Oaxaca

Abstract

A common forgery technique is to use molds to create a suite of objects. This article introduces a new technique to identify objects made with the same mold through the comparison of 3D models created using structured light scanning (SLS). SLS data, when analyzed with CloudCompare or other point cloud processing software, provides quantitative data on the variation between models that can be visualized in scalar fields. Inexpensive, adaptable, and non-destructive, the technique produces a digital signature for a mold that can be used to identify matching examples within a collection and be circulated between institutions. We demonstrate this technique on three forgeries of Zapotec urns from Oaxaca, Mexico, in the collection of the Royal Ontario Museum that were created in the early twentieth century AD.