Low Cost Geotagging

I decided a while ago that it would be useful to "geotag" my photographs, i.e. to automatically record the location from which each is taken and add that to each images's metadata. As my next photographic trip is to Iceland and I rate my chance of correctly remembering and spelling all the Icelandic names as about 0%, this could be very useful.

I looked at commercial solutions, but they have several drawbacks, including the need to carry at least one more gadget, and some questions about how they would fit with my photographic workflow. Then I realised that I could achieve a similar result using just my new mobile phone and some low-cost software which can integrate neatly with my Bibble-based workflow.

The core of the commercial solutions is a small dedicated GPS receiver which records your "track" over time. However, as most recent smartphones also incorporate GPS this is something the phone should be able to do, and true enough there are "apps" for most phone platforms which achieve this. My HTC is based on Windows Mobile 6.5, and the choice was a bit limited, but I tracked down a free piece of software called GPSToday from www.geoterrestrial.com which does the job fine. I have it set to get a GPS location every 10 mins when it can get a signal, and this seems to be a reasonable balance between resolution, file size and battery drain (no more than an extra 5-10% per day).

When out shooting you just need to make sure that your phone and camera are set to the same time (and time zone if they support it), and that your phone is exposed enough to get a regular GPS fix. I try and remember to get a manual fix at the start and end of shooting at each location, but this is probably not strictly necessary.

When you've finished shooting and downloaded your images, the next step is to get the tracks into GPX "track" format. (This is a standard XML format for this type of data.) You may be lucky and your phone/app support this directly, but if not you'll need to convert your track file(s) using GPSBabel ( www.gpsbabel.org), which can convert any GIS data format into any other. This can take a bit of work to set up, but eventually you'll have files full of <track> elements and you're good to go.

The actual geotagging is done by the Geotag program. This is written in Java and doesn't need much installation, but you'll also need to install and locate ExifTool (www.sno.phy.queensu.ca/~phil/exiftool) which does the work of reading and writing the image metadata. It's worth reviewing the settings and in particular how the location data is saved. You have the option of writing direct to the image file, but it's probably safer and in some ways easier to select the "Always write to XMP files" option.

The first step is to "Add images from directory..." - simply browse to the directory with your incoming images. If you shoot RAW+JPEG like me you probable want to just select the RAW files. Next, you select your track file via "Load tracks from file...". Then you select the images you want to tag, and right click to first "Find locations - for selected images", then "Location Names - for selected images" if you want toad textual location information as well as coordinates. If you need to manually adjust any of the tagging information then Geotag makes it easy to do so.

The geotagging information is saved automatically. You can then open the images in Bibble. The act of doing so copies the geotag information to Bibble's settings, so it is written to Bibble's own XMP. Files, and into any output files. Once this is done you can get rid of the Geotag XMP files.

All this software (apart from Bibble) is available for a small donation and on most platforms. Have fun!