(YouTube Link)
The above video is a reconstruction of the Croatian city of Dubrovnik. Rebecca Boyle writes in Popular Science that computer scientists at the University of Washington's Graphics and Imaging Laboratory have been using Microsoft's program Photosynth to compile Flickr images of major landmarks in order to create 3-D digital models:
"The key difference is that Photosynth was aimed at doing a single monument or landmark, which meant that it was scaled to a couple hundred or a thousand photographs, after which it became too slow," said Sameer Agarwal, an assistant professor at UW who worked on the project. "We can now process truly huge data sets -- the big breakthrough here was being able to match the images fast."
A series of videos on the project Web site lets visitors fly through landmarks like St. Peter's Basilica, the Colosseum and Venice's San Marco Square. For much smaller Dubrovnik, you can see the whole city, including mountains in the distance.
Each video includes clusters of small diamond shapes, which represent each photographer and his or her vantage point.
http://www.popsci.com/gear-amp-gadgets/article/2009-09/building-virtual-cities-automatically-150000-flickr-photos