Are there any parts of our planet's surface that don't yet appear in some selfie or another? Probably not, save for the deepest, darkest, wettest corners of our jungles and the coldest, driest, most forbidding windswept ice sheets of the poles. And even in those places, scientists have begun to set up temporary photography stations. Now, a team of engineers has figured out a way to put all those selfies to use – for science.

When we snap a photo, whether with our smartphone perched atop a selfie stick or the traditional way with a single-purpose camera, lots of the resulting images wind up sitting in online databases like Flickr or Picasa. And since many of those photos are publicly available, a group of researchers from Google and the University of Washington decided to analyse them using a process they call "timelapse mining from internet photos". 

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The notion of creating a timelapse from a series of photos is not new. Most smartphones now come equipped with software for creating them, and many timelapse videos have been created from cameras kept at particular locations, like camera traps trained on penguin colonies in Antarctica or set up to record a group of hyenas scavenging a tasty carcass. A bigger challenge is to combine photos taken by different people with different phones or cameras, processed with different software or applications, at slightly different vantage points and at different times of the day or year.

"Creating high quality time-lapses from Internet photo-sharing sites is challenging, due to the vast viewpoint and appearance variation in such collections," write the researchers. To overcome those obstacles, the team created a new technique for "producing extremely stable videos", in which changes in things like viewpoint or the amount of ambient light available become "almost imperceptible". That, they say, will allow viewers to focus on more important changes in a landscape that occur over a longer time scale.

In all, the researchers mined more than 86 million publicly available photos and from them discovered more than 10,000 timelapses. The shortest timelapse was constructed from 300 photos; the longest was made of more than 10,000 individual shots. 

But this isn't just a fun party trick. Timelapse videos such as these can help scientists look at vegetation growth season after season to see how phenology (the timing of biological events) changes as our climate changes. One of the timelapses the researchers created, for example, documented the blooming of flowers in San Francisco, California. They can also help document geological changes, like the retreat of a glacier or the growth of a hot spring due to mineral deposition, both of which also emerged from the researchers' algorithms.

Who knew? It turns out your vacation selfies actually do provide a service to science.

Top header image: CEBImagery, Flickr