How to geotag images
There are a variety of different ways to geotag photos. The one you use will depend on the device you're using to take them and the way in which you want to make use of the finished product.
The most accurate method of pinpointing your exact location when taking photos is to make use of the Global Positioning Satellite (GPS) network that is constantly sweeping through the skies above our heads. By tracking multiple satellites and comparing the signals received from each, a GPS receiver can determine where you are on the surface of the globe to within a couple of metres.
But while GPS capabilities are already in widespread use in personal navigation devices, they're yet to make the move into digital cameras. The biggest challenge is to find a way to add the feature without sacrificing battery life or adding significantly to a camera's weight.
However all the major manufacturers are working on it and we can expect to see GPS-enabled digital cameras on the market within the next 12 months.
But, while you wait patiently for these new models to appear, there are some simple ways you can start geotagging your photos right now:
external GPS receiver
Use an external GPS tracker
If you're using a digital camera, one option is to also use an external GPS receiver. There are various models available but all fall into two main groups.
The first takes a note of your position using GPS and keeps a log in an internal file. By synchronising the clocks in both the device and your camera, a PC-based application can later match the time stamps on your photos with the tracker's record of where you happened to be. This data is then added to each photo as a geotag.
The second option, if your camera supports it, is to directly connect an external GPS receiver. This feature is currently available only in high-end cameras (such as Nikon's D3 and D300 and Canon's 40D), but means that GPS positioning details can be added as each photo is taken, ensuring locations are recorded accurately.
Apple's iPhone 3G features GPS
Grab your GPS mobile phone
Now that growing numbers of mobile phones are sporting GPS capabilities as well as digital cameras, it makes them a natural choice for the geotagging enthusiast.
"Sailors and truckies have been using GPS for years but now it's becoming popular for everyone and being used for applications such as photography," he says. "It will eventually become the norm to geotag all photos in the same way as people have added captions in the past."
Nokia plans to make the software needed for geotagging a standard feature of future phones. Users of a range of existing handsets need to download a small application and install it on their device. Once operational, the software checks for a GPS signal and, if available, automatically adds the appropriate information to each photo as it is taken.
Other handset makers, including HTC, Sony-Ericsson and Motorola, are expected to add similar offerings to their GPS-enabled handsets.
Geotag photos manually using Google Earth and Picasa
Do it manually
Another option is to wait until you've finished taking photos and add all the location details once you've downloaded the images to your PC. There are a variety of ways to do this, but one of the most straightforward uses a combination of Google's Picasa software and the company's Google Earth application.
After downloading your photos into Picasa, it's simply a matter of clicking on the tools tab and selecting the 'Geotag with Google Earth' option. This opens the mapping application in which you navigate to the place where the photo was taken. A single click then embeds the relevant latitude and longitude details into the photo's EXIF metadata file.