Techniques

Using GPS Hardware and Software to Document Where Your Photographs are Taken

by Donald Cohen | September 1, 2006

Software screenshotI have been doing a fair amount of traveling and photography over the last few years, and frequently run into problems determining exactly where any given photograph was taken. My camera does enable me to attach voice files to images, and I have thought of using this to record where I am, but this seems cumbersome and eats up space on storage media. I have long used GPS with my laptop to help us get around unfamiliar places when traveling, and recently I’ve come up with a practical system to use this technology to effectively and efficiently record exactly where my photographs have been taken.

The first step in the process is selecting a GPS receiver. This is a fairly small device which links to the Global Positioning Satellites (hence the term GPS), to determine your location in real-time. There are many such devices out there, but most require them to be used with a display unit of some sort, such as a laptop or PDA, typically with a serial port or USB hardwired connection. There are also “all-in-one” devices, but these are typically larger and heavier, and not suitable for what I am trying to accomplish.

I have been a long-term customer of Delorme, who makes mapping hardware and software, and not too long ago they came out with an intriguing little device, called the Blue Logger GPS Receiver. This compact unit has two features which made it ideal for my purposes: Bluetooth technology and internal storage.

The Bluetooth functionality enables it to communicate with various devices using a wireless connection. This allows me to use it with my laptop, and what’s even more fun, with the Palm T|X I purchased last fall. Combined with TomTom Navigator software (which I find superior to Delorme’s HandHeld software), I can use the BlueLogger and Palm T|X to create a very portable and versatile GPS system to use in the car, when hiking, and in other situations.

The internal storage of the BlueLogger is a crucial feature for photography: it can store up to 50,000 waypoints internally, functioning entirely on its own, with no need for a connection to any other device. Furthermore, you can program it to control the frequency at which it store points, according to travel speed, distance, etc. The bottom line here is that I can turn it on, clip it to my belt, and it will record exactly where I am as I shoot. That data can later be downloaded to my computer.

The BlueLogger is by no means the only device to provide this functionality, so this is not a commercial plug, and I certainly have no proprietary interest here. If you can find something that will enable you to log your location as you shoot, and later access those waypoints, then you’ll be in great shape.

The next part of the process takes advantage of one of the unique features of digital photography – virtually all cameras record a time and date stamp in the “EXIF” image data. And since the BlueLogger records my position by time and date, the final step will be to match the GPS and EXIF data.

There are several different software applications that I considered that can match up the time/date stamps from the GPS and EXIF headers. These are the ones I looked at:

  1. Earthmate Image Tagger: this is also free, provided by Delorme, and will create a map overlay in Street Atlas and similar Delorme applications, showing image location, with a thumbnail of the image as well.
  2. RoboGEO: this is a low-cost application ($34.95 as of the date of this article) and is extremely versatile. It allows you to add GPS coordinates to your EXIF headers, stamp this information to the image itself, and create Google Earth maps or mapfiles. This is the application I ended up purchasing and using.

GPS technology is not a fully “mature” field, so not unexpectedly, I ran into some file format issues. GPS data can be recorded in a variety of formats, with many applications, such as Delorme, using their own proprietary files. But fortunately, I found tools available to convert to or from virtually any file format. Here are the two most useful sites I have found so far:

  1. GPS Visualizer: a free, very helpful site, with versatile conversion capabilities. The conversions are done online, rather than having a separate, downloadable program.
  2. GPS Babel: also free, this is a command-line downloadable program. I haven’t had to use this yet, as GPS Visualizer provides an easy to use “shell” to access GPS Babel’s capabilities, without having to learn the somewhat complex user interface and command structure.

Let’s now move on to how this all gets used in the real-world. When I start shooting, I turn on the BlueLogger, put it on my belt, or in a pocket, and verify that it has initialized and locked in my position (a flashing yellow light appears). I then just shoot as normal, without having to think about location issues any more, other than to just periodically check that the GPS is functioning and locked on.

All of these programs work only with JPEG’s, not RAW files, so I first process my images with my usual workflow, and end up with a folder of JPEG’s. Next, using a Bluetooth connection, I couple my computer to the BlueLogger and download the data, using Delorme’s “GPL” format. I then go to the GPS Visualizer website, and using its GPS Babel shell, convert the GPL data to the more standard GPX format. This step is a little tricky, as it first gives you an XML version of the file. In IE6, just select View… Source… and then save this text file with the GPX extension, and you’ve got what you need.

RoboGEO v3.0 screenshot

Next, I open up RoboGEO, and it basically walks you through the next steps (see screen capture, above). You first point it to the folder containing your images, then the GPX file just created, and it then does its thing, matching up the time/date stamps. You then have several options on what to do next. You can add the GPS data to the EXIF headers, and/or create Google Earth files, which to me is what really makes this whole process a lot of fun.

Google Earth is a neat application, which allows you to navigate around the entire planet, viewing actual satellite imagery. Once you install the application on your computer, you can see an example of how this can be used with your photographs, by clicking on the following link:

I have to admit that in reading through this, it seems like it’s fairly complicated and time-consuming. And getting up to speed will require some time and effort. But once understood and set up, with all the tools in place, it works quite well and efficiently. It will fully document where your photos have been taken, and gives you many options in dealing with the geographical location and presentation of your photographs.

About the Author

Donald Cohen obtained his doctorate in medicine at State University of New York and has been practicing ophthalmology for twenty years in his clinic in Mooresville, North Carolina. His passion for photography goes back as far as thirty years; to see his images or find out about his 2006 Costa Rica workshop, please visit his website at www.dlcphotography.net.

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