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Last Updated: Tuesday, 10 July 2007, 11:31 GMT 12:31 UK
New software lights up archaeology
New software which works out much more realistically how ancient buildings would have looked in their glory by generating accurate plays of light sources has been developed by scientists in England.

Virtual Hagia Sophia
The software maps lighting details onto virtual recreations of places

The project, developed at Warwick University in the West Midlands, brings ancient architectural features to life through a revolutionary sophisticated modelling of light.

This allows archaeologists to study how buildings and artwork would have really looked at the time, right down to the differing lighting provided by the types of candles used.

"What you need to do to get an accurate image is model exactly the physics of the light - what colour the light source is, how it moves within the environment, and how it reflects and refracts off all the different surfaces," said Alan Chalmers, professor of visualisation at the Warwick digital laboratory.

"Once you've modelled the physics right, you're modelling closer to what nature does - and you're achieving a realistic, physically-based image, and you can use that as a tool to understand what the environment really was like."

Lighting difference

The software works by modelling the environment of a ruin or a building with laser scanners, and creating a three-dimensional image of what it would have looked like - as most computer modelling software is able to do.

But the next step is to model the light with a spectral radiometer, which tracks how much red, blue and green is in the light. The software then works out how the materials reflect that light.

I think people are always interested in the past - if they go to Rome or Pompeii and see the frescoes, they think, 'what did this look like in Roman times?
Professor Alan Chalmers
The final stage is displaying the image. Professor Chalmers explained that computer monitors are typically very bad at displaying images, with the difference between the lightest and the darkest pixel being 100 to one - which means it cannot properly show bright images.

Consequently the Warwick team got a high-dynamic range display from Canada, where the difference can be up to 75,000 to one.

Professor Chalmers said that he could not stress enough the difference that accurately rendered lighting makes.

"It's chalk and cheese - it's the difference between some artist's impression and the real illumination," he said.

"Try it yourself - if you take your room at home with the main light on, and then compare it to what it look like with just a single candle on, your whole perception of the environment is very different.

"The Byzantines were using a lot of gold in their artwork, and that's very important, because the gold reflects this light, and the flickering is really picked up in the glow and the halos of the saints - they are really accentuated by the light."

Replica candles

The project is based on Byzantine art found in Cyprus - a major part of the Byzantine empire.

Byzantine mosaic detail in The Chora Church, Istanbul
Placement of lighting was crucial to Byzantine artwork

It is known from evidence from historical documents and chemical analysis what materials were being used to make their candles. To accurately recreate the lighting, the project makes replica candles from the same materials, and then records how bright and colourful they are.

But while such efforts may appear only of interest to a select group of archaeologists, Professor Chalmers insisted they have relevance to ordinary people too.

"I think people are always interested in the past - if they go to Rome or Pompeii and see the frescoes, they think, 'what did this look like in Roman times?'," he said.

"This technology will allow you to do that. But of course it is not only applicable to archaeology - the same techniques of physically modelling the light can be used for if you want to repaint your apartment. You can see what it would really look like if you changed the lighting scheme.

"We use it for product design and medical visualisation and lots of other things - it's just that archaeology is a particularly challenging application, which is why we've focused on it."

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