Near-infrared focus-stacking photogrammetry for surface morphology analysis and text recovery in Herculaneum papyri

Greek papyri are an important source of information about materials and manufacture of ancient bookrolls, and the texts they transmit contribute to our knowledge of classical literature and history. Nevertheless, access to their contents is not always effortless, such as in the case of carbonised Herculaneum papyri, where the black charred substrate is morphologically complex and the text on it is indistinguishable. Herculaneum papyri– the only classical library directly survived from antiquity – were preserved through carbonisation by the eruption of Mount Vesuvius in 79 AD. The capacity of reading the text, hidden between papyrus folds and overlapping layers, is crucial for their interpretation, representing, at the same time, a methodological challenge. In this paper, an experimental approach has been developed by using Near-Infrared Macro Focus-Stacking Photogrammetry aimed at enhancing our ability to read the text contained in unrolled papyri and gaining new information about the morphology of the papyrus substrate.