Putting a face to the past

The computer system helps speed up the process of re-creation.

By Monise Durrani
Producer, Click On

What do Johann Sebastian Bach, Saint Nicholas, and the firstborn son of Pharaoh Rameses II all have in common?

The answer? All their faces have been reconstructed using cutting-edge computer technology.

Dr Caroline Wilkinson is a forensic anthropologist, recreating faces from human remains for archaeological and police investigations - bringing the past to life.

Her workshop at the University of Dundee is covered in model heads, created using traditional methods of layering clay on top of a plaster-cast skull. Sharing the space is a large computer system.

"Today we can use information from 3D surface scans or CT scans of the skull, import them, and use 3D modelling or 'virtual sculpture' to create the same muscles that we would create in real clay" said Dr Wilkinson.

Feeling bones

She has adapted technology originally developed for industry, for example when multiple exact copies of objects, such as engine parts, are required.

Animators and artists next picked up the process and it is now widely used for 3D modelling.

It makes people respond to it in a more human way - they see it as an individual rather than human remains Dr Caroline Wilkinson

The system has one crucial piece of hardware; a mechanical arm with a pen-like attachment at its end.

It is used in a similar way to a computer mouse, but with a key difference - the tool gives haptic feedback, which means that the user can "feel" the surface of the model being worked.

Said Dr Wilkinson: "It's not quite the same as using your hands, it's more like sculpting with a tool - you can feel it in exactly same way."

Dr Wilkinson's pioneering reconstruction project was the skull of a 3800 year old Egyptian mummy which had already been through a CT scanner.

The CT scan allowed Dr Wilkinson to see and remove layers from the original object.

With a mouse click she could swoop through the sarcophagus, wrappings, and preserved soft tissues, to the bone beneath.

The first stage of virtual reconstruction mirrors the real process - the placement of pegs that indicate tissue depth.

When modelling by hand, wooden pegs have to be placed using a ruler and a scalpel - the computer is simpler and much more accurate but not faster.

Facial reconstruction is always a painstaking process

"We have to follow the same rules and go through the same analysis, so it takes the same amount of time," said Dr Wilkinson.

Lost looks

What does speed up the reconstruction is that the database of pre-modelled muscles alongside features such as ears and noses that can be applied - far faster than building them from scratch every time.

Adding the muscles gives the face its shape.

"We all have the same muscles, but because every skull is a slightly different shape, each muscle is slightly different on each individual" said Dr Wilkinson.

Throughout the process, she relies on the haptic tool to shape and mould the face. After the muscles comes eyeballs, ears and the nose - stretched to fit the individual - and then finally the skin and hair.

A key advantage of the computer system is that as Dr Wilkinson works, she can turn layers on and off, switching from skin to the muscles or bone. "We can refer back constantly, which is something you can't do with the traditional methods because as soon as you put clay onto a skull you're covering it up".

And importantly, the technology means that delicate human remains can be analysed without handling them. "We can be non-invasive, so if we have an ancient Egyptian, we don't need to remove the soft tissue to see the bone." she said.

Information can also be transferred quickly - scan data can be e-mailed from anywhere in the world, rather than having to transport skulls or casts of the bone. "It's a more adaptable and flexible way of doing reconstruction."

The technology also allows Dr Wilkinson to assess the accuracy of her work, comparing her models to faces of living people. And she believes that people react well to the realism of the computer images. "I think it's why people respond enthusiastically.

"They're getting a 21st century version of a face of someone who lived two or three thousand years ago, and that can be quite moving," she said.

"It makes people respond to it in a more human way - they see it as an individual rather than human remains."

Click On can be heard on BBC Radio 4 at 16.30 on Monday 1 September 2008 and on Listen Again for a week after broadcast.