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A delicate, antique Buddhist scroll crafted by Mongolian nomads has finally been unfurled after spending decades in museum storage. But the team at Germanyâs Helmholtz-Zentrum Berlin (HZB) research institute didnât risk any damage by physically unrolling itâthey peered inside using a combination of 3D X-ray tomography and AI assistance. The process, as well as what they found written inside, are detailed in a study published in the Journal of Cultural Heritage.
For centuries, the nomadic peoples of Mongolia owned only what they and their pack animals could carry. For Buddhist families, this often included a gungervaa, a portable shrine containing artwork, decorative objects, and other spiritual keepsakes. Some of the most notable items were dharanisâtiny, tightly rolled scrolls featuring common prayers wrapped in silk that generally measured no more than 1.9 by 0.7 by 0.7 inches. The tradition was almost entirely wiped out during the Soviet-backed Mongolian Revolution of 1921, with many of the artifacts destroyed in the process. One shine survived the era, and although its origins are unclear, the relic ultimately arrived at Germanyâs Ethnological Museum of the National Museums in 1932.
Much to conservationistsâ dismay, the shrine is no longer arranged as it was when it entered the archive. After being disassembled for storage, some items were damaged during World War II, and four gilded bronzes and a small painting have disappeared entirely. Nonetheless, over 20 objectsâincluding fabric flowers and statuesâare still preserved at the Ethnological Museum, along with three small dharanis in yellow silk bags.
Each scroll was wrapped in a yellow silk pouch. Credit: Journal of Cultural Heritage
Scanning at sub-volume levels
Until only a few years ago, accessing the scrolls required archeologists to extract and unroll the delicate papers without compromising the materialsâan extremely risky venture. Rather than risk ruining the scrolls, museum researchers requested to borrow a 3D X-ray topographical scanner from the countryâs Federal Institute for Materials Research and Testing (BAM).
The scanner relies on synchrotron tomography, an advanced imaging method that uses hard X-rays to compile 3D representations of an object, beginning at the microscopic level. While frequently used in engineering and material sciences (such as advanced battery research), preservationists are increasingly utilizing the technique for cultural and archeological work.
Operating the scanner on the dharanis presented a hurdle, however. The equipmentâs imaging beamlines have a limited field-of-view, requiring the handlers to image the objects as a series of âsub-volumesâ at multiple height positions. According to the study, each sub-volume required a stack of 2,570 projects taken over 180 degrees. Once finished, these scans could be combined to form a single, detailed image.
Each scroll was tightly wrapped around 50 times. Credit: Journal of Cultural Heritage
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