Virtual unraveling may sound like what you do when you’re trying to understand Donald Trump’s financial arrangements. In fact, it is a sophisticated mix of technologies that may provide a key to accessing information held on ancient and damaged scrolls, if the work of Cardiff University researchers and others bears fruit.
The U.K.-based university says in a statement that researchers have been able to use virtual unraveling on a 16th-century scroll from Diss Heywood Manor in Norfolk, England, to access details on it. The scroll was “severely charred, damaged and fused together with no possible way of physically opening the scroll without destroying it.”
The 270-millimeter-wide document should contain information on everyday life at the manor, such as details on property transactions, disturbances of the peace, and fines, as well as names of jurors. The researchers’ first use of virtual unraveling was on the Bressingham Manor scroll 5 years ago (see a “fly through” of it here). Since then, they and collaborators elsewhere have refined their technique. It includes x-ray tomography—usually applied in the medical field—which was used to create thousands of thin cross sections of the scroll. In each cross section, says the statement, “ink from the scroll is made visible as bright blobs. … Using highly advanced computer algorithms, the team are then able to piece together each of the cross sections and their associated ink marks to form a flat representation of the scroll.”
Challenges and Successes
Paul Rosin, a professor at Cardiff University’s School of Computer Science and Informatics and principal investigator on the project, tells NewsBreaks, “The X-ray scan is a 3D volume of data, i.e. a stack of thousands of images. We analyse this data to reconstruct the shape of the parchment. This allows us to determine the appearance of the parchment, and to synthesise an image of it as if it were unrolled.” He and his colleagues began working on virtual unraveling in 2008.
Rosin says that segmenting the images is the most difficult aspect of the work. “That is, in each image from the stack of images provided from the X-ray scanner, the sheet of the parchment has to be separated from the background (mostly air) which is relatively simple, and also from other parts of parchment which it touches if it is tightly rolled. The latter is very challenging, as the layers of parchment are often squashed together, and no gap between them is visible.”
The Diss Heywood scroll contained four sheets of parchment and many touching layers, which meant text could possibly be assigned to the wrong sheets. In the statement, Rosin says, “In addition to this, the scroll was heavily discoloured and creased and was covered in soot-like deposits over the entire exterior. Nevertheless, we’ve shown that even with the most challenging of samples, we can successfully draw information from it.”
The project involved collaborating with experts at Queen Mary University of London—where the X-raying and scanning was undertaken—Beihang University in China, and the Norfolk Record Office. Extensive technical details can be found here.
The Future of Virtual Unraveling
Rosin says in the statement, “We know that there is a large body of historical documents in museums and archives that are too fragile to be opened or unrolled, so we would certainly welcome the opportunity to try out our new techniques.” The Cardiff University method “is heavily automated, opening up the possibility of exploring a larger range of documents and even other types of media, such as old and damaged camera films.”
Rosin hopes to undertake further work on other damaged documents. He tells NewsBreaks, “We have gotten in contact with several new people in the last month, and we are hoping to get some documents scanned. But it takes a long time to organise, as there are many formalities to sort out before archival documents can be transported. Also, we have to check that scanning is feasible, e.g. the document is not too big, the ink has sufficient X-ray contrast, etc.”
He adds, “Over the years we have been able to scan new scrolls, some of which are in a more damaged state than we have seen in the past. This has necessitated developing our techniques to cope with the new data. For instance, our original result for the Bressingham [Manor scroll] … was only [being] able to process half the scroll, whereas our new results published this year were able to process all the scroll. In the future we will continue to develop the technique to cope with parchments that have increasing amounts of damage.”