A NEAT APPLICATION of archaeology, tomography and computer science has virtually unrolled a fragile 2000-year-old scroll. In today’s title, I invoke the memory of Superman/Clark Kent’s boss, Perry White, editor of Metropolis’s Daily Planet, who often exclaimed “Great Caesar’s Ghost!” Here, however, it’s Lucius Calpurnius Piso, Caesar’s father-in-law, who deserves partial credit.
Lucius Calpurnius Piso, c. 100 B.C.–43 B.C., was likely the owner of a grand villa in Herculaneum, near Pompei. The villa contained an extensive library, many of its papyrus scrolls carbonized by the eruption of Mount Vesuvius in 79 A.D.
Recovery began in the 18th century, but the library’s charred documents have challenged archaeologists trying to decipher them. Over the years, Herculaneum scrolls have been damaged or destroyed, until modern non-intrusive methods were developed.
Another excavation site, En-Gedi in Israel, yielded similarly wrapped papyrus dating from a bit later, 100–300 A.D. This site was discovered in 1970, though again the fragility of its scrolls has challenged researchers.
An En-Gedi scroll. This and the following images by Dr. W. Brent Seales.
W. Brent Seales is a computer scientist at the University of Kentucky. He and his colleagues developed a means of peering into these extremely fragile tightly wrapped scrolls and revealing their text. Details are given in their paper, ”From Damage to Discovery via Virtual Unwrapping: Reading the Scroll from En-Gedi.”
Briefly, this virtual unwrapping involves an X-ray scan of the scroll using micro-computed tomography, a technique typically employed for fine-resolution analysis of biological tissue. The virtual unwrapping has three stages, segmentation, texturing and flattening.
At left, cross-section of a scroll, its white lines representing the rolled layers. At right, a reconstruction of one layer.
Segmentation recreates layers of the wrapped document that may hold writing. A triangulated surface mesh then forms a piece-by-piece approximation of the chosen surfaces.
Texturing identifies intensity values in the geometric model, blobs of ink versus plain papyrus. Analyses in this stage help to overcome “noise” in the imaging and incorrect location of blobs on surfaces.
Flattening, as its name suggests, transforms the 3D model into a 2D virtual surface. These pieces of virtual manuscript are then optimized into the final document.
The En-Gedi scroll, virtually unwrapped.
The En-Gedi scroll turns out to be the first eight verses of the Book of Leviticus. It is the oldest Pentateuchal scroll in Hebrew other than those of the Dead Sea Scrolls. These latter were discovered between 1946 and 1956, relatively well preserved in arid caves of Qumran in Israel’s occupied West Bank.
Seales and his colleagues will be applying their Volume Cartography technique to the Herculaneum scrolls. He also notes that their collection of software will become open source (that is, freely available and upgraded) when his government grant ends. ds
© Dennis Simanaitis, SimanaitisSays.com, 2016