The mix and match of digital convergence is constantly creating hybrid products that change what we can do. A scientific/military tool — the global positioning system device — has spawned consumer spins ranging from vehicle navigation systems to a modernization of the good old scavenger hunt, aka geocaching. Tie a GPS unit to a digital camera and you have yet another variation — photo geotagging.

The Basic Process

In its most basic form, photo geotagging involves identifying where you took a picture with GPS co-ordinates — longitude, latitude, etc. The process is possible because both the camera and the GPS unit contain a clock. Synchronize the clocks on the two devices and you have a way of creating time-matched data. The data from the camera are simply the images you take. The key GPS datastream is found in the track log (not all GPS units create a track log; for photo geotagging, you’ll need one that does, and usually following a standard such as the NMEA 0183 data protocol). The third component is a software utility that uses synchronized clock data from the two devices to match the data streams. Simply put, if you took a photo at 2:14 pm, the software will find the location co-ordinates logged by the GPS unit at 2:14 pm, and then tag that photo with the location information by writing the appropriate GPS data into the EXIF header of the digital image file.

The basics of geo-tagging might not seem too exciting unless you are a database freak, but there is a fourth component that puts photo geotagging on a world stage. Match those GPS-tagged photos to something like a Google Map and suddenly you have a way to show people what the ground space actually looks like at any given map point. And that is the essence of photo geotagging. Many photo-geotagged pages can be found on popular photo sites.

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