Scanners throw laser light on the 'dark ages' in Orkney

By Huw Williams
BBC Scotland reporter

image captionOne rune carving is on a stone hidden by grass at the base of a wall in ruins of the Bishop's palace

The latest laser scanning technology is being used to investigate ancient inscriptions left on Orkney by the Picts and the Vikings.

Experts from Sweden hope their software will make it possible to recognise the work of individual carvers.

The study may tell us more about the transition between the different groups who occupied sites like the Brough of Birsay over hundreds of years.

The team are hoping for preliminary results by the start of 2020.

image captionThe scanner fires out beams of laser light which bounce back and are captured by cameras to build up a 3D model of the stone

But before you can scan inscriptions, like the one on a stone at the base of a wall in ruins of the bishop's palace in the Brough of Birsay, you have to find them.

After several minutes of searching they've found the right place. Then a brief chat about whether it's alright to rip up the turf threatening to overwhelm the carving.

That done, dozens of reflective target point stickers are attached to the stone, and then the scanner is passed over it several times.

A detailed three dimensional image starts to build up on the laptop on the grass alongside the wall.

image captionAs well as the stone that's still in situ there are a number of other carvings inside a building at the Brough of Birsay
image captionIt is much easier to see the laser in in operation on one of the stones that is on show inside

It is possible to spin and rotate the image on the screen - even get the computer to illuminate it from different angles with virtual light which can sometimes throw up details that are not visible with the naked eye.

But the real trick - the thing that makes this project unique - is the powerful software that analyses all the data gathered by the scanner.

Dr Laila Kitzler Åhfeldt, from the Swedish National Heritage Board, developed the program.

"By statistical analysis, I can 'see' if several carvers have been involved. And sometimes I can distinguish between individual carvers, or carver groups", she told BBC Radio Orkney.

image sourceNeil Hanna
image captionThe team came to Orkney after starting by scanning Pictish symbol stones from Orkney and Shetland in the National Museum Scotland in Edinburgh
image sourceNeil Hanna
image captionLooking at the scans on screen may throw up new details - but the real trick is statistical analysis of all the data

That means she should be able to say if two different carvings have been done by people from the same workshop, or who were trained by the same master. Or even if they were done by the same individual craftsman.

And it turns out that the Brough of Birsay, and Cunningsburgh in Shetland, are really special places to do this work.

"They are the only two places in the world where you have three alphabets occurring together from this period", said Dr Adrián Maldonado, Glenmorangie Research Fellow at National Museums Scotland.

"You have runes coming from Norway; Ogham, which was used in Irish and Pictish areas; and you also have the Pictish symbol stones."

image captionAlex Sanmark from the Institute for Northern Studies says the hope is that the study may reveal new details about the transition from the Picts to the Vikings in Orkney

Dr Alex Sanmark, from the Institute for Northern Studies at the University of the Highlands and Islands, hopes the study may reveal new details about how the Vikings took over from the Picts in Orkney.

"There are different ideas of what happened when the Vikings settled," she said. "Some people say that they killed every single Pict. Other people say maybe there was more interaction, and that the Picts gradually disappeared and became Norse."

One possibility - if the software really can distinguish the work of individual masons - is that they might find someone who had been carving Ogham or Pictish symbols who later moved on to carving Norse runes.

"If we found that, that would be absolutely amazing", Alex Sanmark said. "And it would tell us much more about the interactions, rather than there being a brick wall between the Picts and the Vikings."

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