A team of researchers has transformed 86 million photos - gathered from sites such as Flickr, Picasa and others - into stunning time-lapse videos of some of the world's best-known landmarks. The time-lapses show how landmarks as varied as the New York skyline and sand banks in Thailand have changed over the years, using nothing more than thousands of different photos taken by sightseers.

The project - led by researchers from Google and the University of Washington - delivers a completely automated way of adpating the millions of images that are posted to the internet every day. "First, we cluster 86 million photos into landmarks and popular viewpoints," explains the research paper issued by the researchers. "Then, we sort the photos by date and warp each photo onto a common viewpoint. Finally, we stabilise the appearance of the sequence to compensate for lighting effects and [to] minimise flicker."

The researchers generated more than 10,000 time-lapse videos from the 86 million images, showing the enormous potential of the technology. It could, for example, be used to monitor the effects of climate change, showing how glaciers and water levels recede over the years. It also demonstrates how city skylines are changing over time, as buildings are demolished and new skyscrapers appear in their place. Even renovations of individual buildings are captured from the thousands of tourist images.

Not all of the time-lapse videos generated were considered a success. The team claims that 45% of the videos were "good and interesting" with a variety of technical faults marring others. The researchers note how the timestamps that are automatically added to photos by cameras are not always accurate, potentially adding out-of-sequence images into the mix. Combining night and day shots can also create a strange twighlight effect in the resulting time-lapses. At other times, the imaging technology struggles with the rapid rate of change in a particular landscape. "The time-lapse of Las Vegas shows blurring in areas where the geometry changes significantly over time," the researchers note.

Nevertheless, the researchers believe they've found a new way of monitoring many of the Earth's most photographed beauty spots, without relying on specialist camera equipment. "The scale and ubiquity of our mined time-lapses creates a new paradigm for visualising global changes," the claim. "As more photos become available online, mined time-lapses will visualise even longer time periods, showing more drastic changes."