Researchers at London University's Queen Mary College and Cardiff University have used a combination of X-rays and computer modeling to offer historians something they could never have dreamed of: a way to read ancient parchments so fragile they cannot be unrolled.
The result: a system called Apocalypto that lets researchers read the unreadable by creating a virtual version of the documents.
In the pre-digital age, the project's researchers explained, people wrote on parchment paper that was very expensive at the time. For that reason, the pages, also known as palimpsests, were often used over and over again.
Made of organic materials like paper, cloth, and even bark, the scrolls were surprisingly long-lasting, but they were still vulnerable to the passage of time. And while digitization of material means that they can now be preserved and shared more easily, a lot of ancient scrolls are very fragile. That means they're safe as long as we don't mess with them, but if we try to open them they will crumble.
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Hence Apocalypto, a £1.3 million ($1.9 million) collaboration between scientists and historians to find ways to safely access data on degraded, at-risk heritage material.
Paper and parchment (animal skin stretched finely enough to write on) documents -- especially those that have been inscribed with metallic-based, or "iron gall" inks – are the first targets for the new technology. Due to its composition, anything written in metallic ink can be seen by an X-ray. Apocalypto will use a combination of micro tomography (industrial CT scanning) and advanced software-based visualization techniques to build a 3D map of the contents of these documents, revealing the hidden or overwritten layers underneath for the first time in centuries.
The Apocalypto team says they don't know what they might find -- if anything at all. "It's fairly safe to say that we're not likely to be seeing any lost works of Aristotle," Graham Davis, reader in 3D X-ray imaging at Queen Mary University and lead for the Apocalypto program, told Information Week.
"The iron content in the ink gives it its good X-ray contrast," Davis continued, "but this ink also can cause degradation of the parchment and may contribute to the reasons why a particular scroll cannot be opened."
If researchers do find information that's been lost for centuries, it'll because of this imaging technology. The special feature of the scanner, Davis explained, is its use of time-delay integration in the X-ray CCD camera. The camera is moved across the X-ray shadow while being simultaneously read out. The read-out speed and camera motion speed are precisely synchronized to produce a continuous high-quality image; as many as several thousand such images may be needed to reconstruct the full 3-D volume image of the target scroll.
But that image needs to be cleaned up, including removal of "noise" (data that's neither ink nor parchment) and the data fully projected and rendered. The process also involves the use of specially designed surface mesh construction and correction algorithms, Davis said.
"This is a milestone in historical information recovery," said Tim Wess, a colleague of Davis' at Cardiff. "The conservation community is rightly very protective of old documents and isn't prepared to risk damaging them by opening them. Our breakthrough means they won't have to. Across the world, literally thousands of previously unusable documents up to around a thousand years old could now become available for historical research. It really will be possible to read the unreadable."
The Apocalypto project is backed by the British government's EPSRC R&D arm.