A RESCUE mission is underway on the Scottish coast north of Edinburgh. Jonathan's Cave, with its rare trove of 1500-year-old rock art, risks being flooded by the sea or buried in a landslide. But rather than fight the elements researchers have opted to save the cave by putting the whole thing on the internet.
A team led by Joanna Hambly, an archaeologist at the University of St Andrews, UK, is using a series of laser and visual scanning techniques to recreate a virtual cave in minute detail.
Starting last year, the team brought in a low-flying drone to shoot aerial footage of the outside of the cave and the surrounding land. Lasers then scanned the cave, both inside and out, to build a 3D model of the site on a millimetre-scale.
The team also scanned the carvings several times using a variety of techniques. In one, a camera snapped images of the walls as they were lit from many different angles. And another approach, called structured light scanning, projected different patterns onto the walls and then read distortions in the patterns caused by the rock surface. This method provides detail down to the level of 100 micrometres – fine enough resolution to examine each individual hammer blow that made up the carvings.
"We're throwing everything at it. There is a danger that we may lose these caves," says team member Tom Dawson of the non-profit trust Scottish Coastal Archaeology and the Problem of Erosion.
An online walk-through of Jonathan's Cave will go live later this month. As well as clicking to move through the cave, you will be able to use the mouse cursor like a torch to illuminate more than 30 different carvings left by the Picts, who lived in Scotland during the Iron Age. These include images of men and animals, Christian symbols and the earliest known depiction of a Scottish boat. If all goes well, the team hopes to recreate the process for other nearby caves that are also in danger of disappearing.
"One of the objectives is to see which technique is most effective at recording heritage like this," says Hambly.
The project is not the first to create a virtual record of fragile archaeological sites.
"This scarce resource is being lost forever," says Frank Weaver, a documentary filmmaker who has been using Microsoft's Kinect depth-sensing cameras to record rock art in Paraguay. "What better way to save it for future studies and appreciation than online?"
Katherine Tsiang, an art historian at the University of Chicago, has used similar methods to digitally record historic caves in China. But she cautions that even high-tech archives are vulnerable to becoming outdated, or simply forgotten about. "All of this digital stuff isn't permanent unless it's carefully maintained," she says.
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References:
Rutkin, Aviva. 2014. “Digitising cave art will prevent it being lost forever”. New Scientist. Posted: Available online: http://www.newscientist.com/article/mg22229644.500-digitising-cave-art-will-prevent-it-being-lost-forever.html#.U2wCL8ejfmk
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