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Geotagging: how much do your photos give away?


Smartphone camera

In the vast majority of cases, your smartphone will automatically embed your location into every photograph you take. (Source: fotostorm/iStockphoto)

If you don't understand the technology you use, every now and then your ignorance will come back and bite you.

One expensive example of this happened back in 2007 on a US military base in Iraq. Because some soldiers took photographs and posted them on the web, the US taxpayer lost over $100 million.

This new-ish technology that the soldiers didn't fully understand is called 'geo-tagging'. What it means is that when you take a photograph or video, your geographical location is almost always embedded in the digital files of that photograph or video. This happens automatically with practically all smart phones that have a camera built in, and with a few specific digital cameras.

This geographical identification data is usually stored as 'metadata' in what is called an EXIF file, as part of your digital photograph.

EXIF stands for exchangeable image file format. It is an industry standard that specifies the format for images and sound used by digital cameras. But it doesn't store only images and sound. It also stores date and time information, the camera settings that we use to take a photograph or video, a small thumbnail picture to preview the image on the camera's LCD screen, and so on.

But EXIF files are now being used to store extra information, such as your latitude and longitude coordinates. Furthermore, the geo-data stored can also include your altitude above sea level, the direction the camera was facing when it took the photograph, how accurate is your camera's estimate of your location, and even place names.

But how does your smart phone know where you are?

There are a few different ways. They all involve the 2000-year-old technique called 'triangulation'. In triangulation, if you have three known locations, and if you know your exact distance from each of them, then there's only one place you can be.

The first modern method of triangulation uses 'real' GPS, and gets location and time information from GPS satellites orbiting some 20,000 kilometres overhead. But that's expensive. So you don't have to use the satellites. Instead, your smart phone can also work out your whereabouts by knowing the location of the nearest mobile phone towers, or any Wi-Fi hotspots, including the one in your house.

But regardless of how your smartphone knows where you are, the important thing to realise is that in the vast majority of cases, it will automatically embed your location into every photograph you take. If you want to stop it from doing this, you have to dive deep into the settings of your smart phone. However, if you did accidentally imprint geotags on your photos when you took them, you can later remove them with the many so-called 'metadata removal tools' available on the web.

This has "interesting" privacy considerations. If you take a photograph of a painting on your bedroom wall, and then post that photograph on Facebook, anyone can work out the location of your bedroom. A thief can work out that you have gone on holidays by checking your location via the photos you post on the web.

Getting back to the snap-happy soldiers who cost the US taxpayer lots of money, back in 2007 at a military base in Iraq, they took delivery of some AH-64 Apache helicopters. These are not cheap choppers. In 2012, the price of a brand-new one was $38 million. The soldiers proudly took pictures of their new attack helicopters, and then uploaded them onto the web. Almost certainly, the soldiers did not realise that geo-location tags were embedded in those photographs.

According to Steve Warren, a US Army Manoeuvre Centre Of Excellence intelligence officer, "the enemy was able to determine the exact location of the helicopters inside the compound and conduct a mortar attack, destroying four of the AH-64 Apache".

That was an expensive $150 million mistake — but I guess that the soldiers now have had drilled into them just what geo-tagging is. I wonder how long before all us civilians learn about the "Oh My God"s or "OMG"s of geo-tagging.

Tags: mobile-phones, computers-and-technology, information-technology

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Published 05 June 2012

© 2013 Karl S. Kruszelnicki Pty Ltd