Where in the World? Finding Geotagged Photos

Geotagging is de rigueur on most web 2.0 sites these days, location-based social networking tools such as FourSquareFacebook PlacesGowalla coupled to aGPS-enabled smart phone or other devices are obligatory for the technorati, while countless uploads from millions of digital cameras automatically add a place, or geotag, to your photos opening up a whole world of information.

Photos sites, such as Flickr and mashups with Google Maps already allow you to home in on specific images in specific places and geo-referenced data can be very useful to artists, scientists, and armchair tourists as well as many others. A geo-reference associates a place with a piece of information (which could be anything including a photo), geo-referencing can be at the level of a precise grid reference, an address, a street, a town, or country. Given that places are “everywhere” it is easy to see how such referencing could be very useful but also overwhelming, especially when there is such a wealth of photos of so many places online.

Extracting the geo from structured data is difficult but from unstructured data it is even harder. How does a search spider or software agent distinguish between the hotel known as the Paris Hilton and the celebrity of the same name and what does the distinction know about location?

There are various tools, including the aforementioned Flickr, which allow geotagging of images whether or hotels or celebrities. And the numbers seem to be growing exponentially, which means exponential growth in information and perhaps the same growth rate in effort needed to extract anything useful from the repositories. For example, in 2003, there were just 10,000 geotagged photos on Flickr. That had grown tenfold by 2006 in 2009 there were 100 million and today the site reports that it has 148,749,626 geotagged images.



Flickr’s map tool lets you explore the world of those geotagged images, as does the Panoramio tool from Google. Each has its pros and cons according to Davide Carboni of the Centre for Advanced Studies in Pula, Italy, and colleagues. They have compared and contrasted Flickr’s and Google’s approach to visualizing geotagged photos and also throw into the mix their own tool – Geopix: Fractal View (http://opensource.crs4.it/geopixrun/script/fractal.html – built for demonstration purposes only; an iPad app is available here). They have also carried out users tests using eye-tracking software and questionnaires to find out which kind of tool is most useful to users attempting to search and study geotagged photos.



The researchers suggest that both Flickr and Panoramio require an excessive visual effort for users continually flitting between thumbnails to the map and vice versa. Whereas their Fractal View tool an entirely new interface. “Fractal View implements the magnifying glass metaphor: the nearer the objects are, the larger they are displayed and vice versa,” the team explains.



Eye-tracking software showed, contrary to intuition that the “distances” moved by the users’ eyes (saccades) were actually almost identical between Flickr, Panoramio and Fractal View. However, the team points out that, although their software has some shortcomings, the amount of useful eye movement when using it is much greater than with Flickr or Panoramio.



In Panoramio, and to a lesser extent in Flickr, long saccades are needed to move from the thumbnails to the map after having selected an item. The saccades in Fractal View are merely for wandering from one image to another rather than involving user effort and so are useful rather than functional, the team says. They are currently implementing improvements to the system based on user feedback.

Davide Carboni, Valentina Marotto, & Pietro Zanarini (2011). Visualisation of geo-tagged pictures in the web Int. J. Web Eng. Technol., 6 (3), 220-242

This article has been reproduced from Sciencetext technology website. Copyright David Bradley.


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About David Bradley Science Writer

David Bradley has worked in science communication for more than twenty years. After reading chemistry at university, he worked and travelled in the USA, did a stint in a QA/QC lab and then took on a role as a technical editor for the Royal Society of Chemistry. Then, following an extended trip to Australia, he returned and began contributing as a freelance to the likes of New Scientist and various trade magazines. He has been growing his portfolio and and has constructed the Sciencebase Science News and the Sciencetext technology website. He also runs the SciScoop Science Forum which is open to guest contributors on scientific topics.
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