Geotagging (sometimes called Geocoding) is tagging, or marking, your photos with information about the location where they were taken. Why might you want to do that? It would be good to know if you wanted to go back and take the same photo at another time. Or if you wanted to be able to see on a map, or show someone else, where the photo was taken.
When you Geotag a photo, the location information (latitude, longitude, and possibly elevation) are saved in the metadata of your photo, specifically, in the EXIF portion. Many photo editing and viewing programs will display that data if it is entered. Here is an example of how that data is displayed in Adobe Lightroom.
Many websites will display where a photo was taken if embedded location information is detected. One example is Picasaweb (http://picasaweb.google.com/). Here is a map showing where the photos I uploaded in one album were taken.
Some cameras will Geotag a photo at the time the photo is taken. Many of today’s cell phones have a built-in GPS, and will automatically tag your photo with location information when you take a picture. And there are add-on devices that will communicate the location information directly to some cameras when you take the photo.
There are a number of devices on the market that are designed to log your position when a picture is taken. Most of these are inserted into your camera’s flash shoe. But you don’t need to use a dedicated device. I currently use a hiking GPS, a Garmin eTrex Vista HCx, and just carry it with me in a pocket or backpack. It is constantly logging my position and time. I later Geotag my photos using a computer program. The program works by reading the time each photo was taken from its EXIF data, then finding the closest time from the information recorded in the GPS track. Once the closest time is found, if the time is close enough to the time of the photo, it records the location from the GPS track into the EXIF information in the photo. This does mean that you need to accurately set the clock in your camera.
Other programs allow you open your photo and open a map, then show on the map where the photo was taken. The program will then record the location you have specified into the photo’s EXIF data.
I use RoboGeo (http://www.robogeo.com/home/) for most of my Geotagging. It costs $79.95 for a single user license, which allows you to use RoboGeo on up to three computers. I have found RoboGeo easy to use and very complete, accomplishing everything I’ve wanted to do, and many things I didn’t know I wanted to do until I used it. You simply point it at the photo (or photo folder) and a GPS track log file, and it will match up the times and write the location information to the photo. It can also write viewable information to the image, and create a Google Earth KML (or KMZ) file showing where each photo was taken.
Another fun thing I use RoboGeo for is to create KML files from GPS tracks that show your track in Google Earth. This is a fun thing to do after a trip – for instance, a hike, motorcycle trip or car trip – to show where you have been. Each point on the route includes your elevation (if your GPS records elevation), location, time, speed, and other interesting information.
Also note that Google Earth can now read GPX (GPX eXchange Format) files directly, but the information displayed by Google Earth alone is not nearly as complete as the information recorded by RoboGeo.
If you didn’t happen to have your GPS along (or forgot to turn it on – my favorite trick) when you took a photo, you can use RoboGeo in conjunction with Google Earth to manually locate where the photo was taken (assuming you know) and then RoboGeo will write the designated coordinates to the photo.
If you use a Garmin GPS device, Garmin’s BaseCamp can Geotag your photos. There are also a number of free programs that can Geotag photos.