Technology

PC 'rebuilds Rome in a day' using pictures from Flickr

3D model of Rome's Colosseum
Image caption Rome's Colosseum, as captured by millions of tourists

3D models of famous landmarks such as Rome's Colosseum have been recreated using millions of pictures from photo-sharing websites such as Flickr.

The images were analysed by a modified home PC and detailed models created in less than a day.

The team behind the system think it may help preserve heritage sites, ensuring they don't end up swamped by tourists.

It was created by researchers from the University of North Carolina, Chapel Hill and Swiss university, ETH-Zurich.

The technique of using millions of photos to recreate detailed scenes has previously been demonstrated by Microsoft with its PhotoSynth technology.

A technique built by researchers at the University of Washington also aimed to recreate famous sites.

But these other systems have needed powerful clusters of computers to perform the necessary image analysis, said Professor Marc Pollefeys.

His team, led by Professor Jan-Michael Frahm, used a home PC, albeit one equipped with four powerful graphics cards.

The cards were the key to being able to do the huge number of calculations necessary, said Prof Pollefey.

The first task was to identify pictures on Flickr tagged with the word "Rome".

Main attractions

A basic image analysis tool then created groups of photographs that had captured the same image - the west side of the Colosseum, for example.

By analysing how the object appeared from different viewing angles and distances, a rough 3D model of the object could be created, said Prof Pollefeys.

They then used detailed analysis of each pixel within the group of photos to study the target object's surface.

"This allowed us to recreate incredibly detailed models of the sites," he said.

As well as making eye-catching virtual models, the system can also highlight where tourists tend to congregate to snap the main attractions, he added.

"So you can also identify other locations where you can get great shots of the same landmark," said Prof Pollefeys.

That could help minimise the impact tourists have when visiting popular sites, by allowing officials to direct them to different parts of the attraction, he said.

It could also help them plan trips more effectively, he added.

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