Now, virtual landmarks can be created using online photos

A new computer technology has enabled people to make virtual models of actual landmarks after downloading their photographs from Internet.

Washington, Nov 2 : A new computer technology has enabled people to make virtual models of actual landmarks after downloading their photographs from Internet.

Usually, members of photo sharing websites snap pictures of their surroundings and then post these photos on Internet. But one group at the University of Washington has done the reverse by downloading thousands of photos from Flickr website and using them to recreate the original scenes.

The study authors, experts in computer vision, believe that online photo-sharing Web sites such as Flickr and Google are the world's most diverse, and largely untapped, source of digital imagery. But the freely available photos on these websites present a challenge: these are holiday snapshots and personal photos, not laboratory-quality research images.

"The big breakthrough here is being able to compute very accurate 3D models from people's vacation photos," said co-author Steve Seitz, a UW (University of Washington) associate professor of computer science and engineering. "The long-term vision is to be able to reconstruct the detailed geometry of all the structures on the surface of the Earth. Many people are working toward that goal, but by using online collections, this work brings in a whole new source of imagery and level of detail," he added.

To make the 3D digital model, the researchers first download photos of a landmark. The computer then finds photos that it will be able to use in the reconstruction and discards pictures that are of low quality or have obstructions. Photo Tourism, a tool developed at the UW, then calculates where each person was standing when he or she took the photo. By comparing two photos of the same object that were taken from slightly different perspectives, the software applies principles of computer vision to figure out the distance to each point.

The group has presently recreated the Notre Dame Cathedral, St. Peter's Basilica in Rome and a model of the Duomo in Pisa, Italy.

According to Seitz, creating 3D reconstructions of individual buildings is a first step in a long-term effort to recreate an entire city using online photographs. "We've downloaded about 1 million photographs of Rome from Flickr," he said. "We want to see how much of the city we can reconstruct-including exteriors, interiors and artifacts," he added.

The group hopes to make significant progress on the Rome project over the next couple of years.

ANI