iPhone users - add GPS Data to your Digital SLR Photographs

Recently I have been exploring different methods for adding GPS data to images captured from digital SLRs. GPS data includes latitude and longitude coordinates as well as elevation. My goal is to utilize online technologies that allow sharing of geotag data such as Google Earth and Flickr. Although many camera makers have dedicated modules available for adding GPS data, they are quite expensive. As an option, several third-party manufacturers sell similar devices at half the cost, however they are still in the range of $100 or more.

A cost-effective solution for users of the iPhone 3G or 3Gs is an application called MotionX GPS. Using a solution based on software has several advantages over hardware devices including cost, as MotionX GPS sells for only $2.99. MotionX includes a host of features that should prove to be useful in the field. The basic function of a GPS tracking device is to record a constant “track” of movement. A track includes information such as time, speed, distance, max speed, and a map of your route. The saved track can then be synchronized with photographs taken during the outing.

So let’s see how this process works. The first step is to synchronize the clock in your camera with your iPhone. Without an accurate timestamp you won’t be able to accurately merge the GPS tracking data with your images. Step number two is to start a new track in MotionX GPS using the track recorder feature. From this point forward it will record my every movement as well as give me an elapsed time readout and distance information as well. At the end of the outing I’ll stop the recording and save the track giving it a unique name.

After the recording is completed you can view the track overlaid on a satellite ( you can also use road or hybrid views) map in MotionX GPS, which supports either MotionX maps, Google Maps, or Bing Maps. At this point there won’t be any correlation between your photographs and the recorded track, this will happen once the track is downloaded to your computer.

At this point I need to export the track out of MotionX GPS. One of the simplest ways to accomplish this is to share it via an e-mail which I send to myself. MotionX GPS can export in the standard .GPX format which can be used by almost any mapping program available.

Once I have downloaded the GPX file as an e-mail attachment, I’ll need to use geotagging software to merge the GPS data with my photographs. At the moment, my favorite tool for this is the HoudahGeo software. While there are free geotagging software titles available for MacOS X, I’m sold on HoudahGeo simplicity, robustness, and speed, which together create a best in class experience for me. While HoudahGeo is a Mac only application, there are many similar titles available for Windows users. There are really only three steps to merging the GPS data with my images with HoudahGeo. The first step is to drag my selected photographs into the HoudahGeo window. My main cataloging tool is Adobe Lightroom, so I create a collection in Lightroom for a specific outing. I then select the images in the collection and drag them into the HoudahGeo application. The second step is to select the downloaded GPX file which HoudahGeo then automatically synchronizes the GPS data with the photographs. The final step is to export the resulting data to Google Maps, or Google Earth, or upload to Flickr. HoudahGeo will create XMP sidecar files for storing the geotag information when using Raw image formats.

The process is now complete and you can take full advantage of the new geotagged data in your images. So what can I do with this new information? Well I can share my walks with the online community, I can illustrate my travels for a blog post, I can even jump start my fading memory when I have trouble recalling my shooting locations. For this quick tutorial I’ve uploaded a Google Earth file in the .KMZ format that includes 14 snapshots taken while on a morning walk along the central lagoon on Bay Farm Island. You will need to have the Google Earth application installed on your computer in order to see the contents of the HoudahGeoTest.kmz file. This link will take you directly to the file. HoudahGeoTest.kmz

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