Rome can be built in a day -- with photos

SEATTLE, Sept. 17 (UPI) -- The ancient city of Rome wasn't built in a day and it took nearly a century to build St. Peter's Basilica -- but now the city can be digitized in just hours.

A new University of Washington computer algorithm uses hundreds of thousands of tourist photos to automatically reconstruct an entire city in about a day.

The tool is the most recent in a series developed to harness increasingly large digital photo collections available on photo-sharing Web sites. The digital Rome was built from 150,000 tourist photos that were downloaded from the popular photo-sharing Web site, Flickr.

Researchers led by Assistant Professor Sameer Agarwal said computers analyzed each image and in 21 hours combined them to create a 3-D digital model that allows a viewer to "fly" around Rome's landmarks, from the Trevi Fountain to the Pantheon to the inside of the Sistine Chapel.

Earlier versions of the UW technology are known as Photo Tourism. That technology was licensed in 2006 to Microsoft, which now offers it as a free tool called Photosynth.

"With Photosynth and Photo Tourism, we basically reconstruct individual landmarks," said study co-author Noah Snavely. "Here we're trying to reconstruct entire cities.

The project that included Rick Szeliski of Microsoft Research, Professor Steve Seitz and graduate student Ian Simon is to be presented next month in Kyoto, Japan, during the International Conference on Computer Vision.