Photo Geotagging is the process of embedding GPS data into an image or video. It's the same as writing details of the time and place on the back of a conventional photograph. I know that my parents have heaps of old photographs without any notes on the back - when & where - all unknowns which makes the photograph pretty much a mystery.
Probably the best known example of geotagging is Google Maps streetview, where Google have captured images of streets and have integrated them into their maps.
Now, using our GPS units, digital cameras, and some clever software we are able to tie it together for our own images.
Where was this taken? Which country? When?
The process of geotagging usually involves taking a GPS tracklog, and matching it to images. The images will have a time and date stamp as part of their EXIF metadata if taken with a digital camera. Software will perform a match between the GPS tracklog and the photo (say if the photo was taken within a few minutes of a point in a tracklog) and embed the latitude/longitude-coordinates into the EXIF metadata of the image.
The GPS tracklog doesn't have to be an ultra high resolution 1 second track, in the example below I used a auto tracklog interval set to 'normal' from a Garmin Quest.
The Geotagging software I use is called Microsoft Pro Photo Tools 2, and in the past I have used GPicSync, but there are heaps of other options out there. Start with http://freegeographytools.com/category/geotagging for a bit of an overview.
The workflow in Microsoft Pro Photo Tools is simple:
Step 1. Drag the images I want to geotag into the image thumbnail pane (grey area) of MS Pro Photo Tools. Select all of the images by pressing <CTRL-A>
Step 2. Click on the 'Load from file' button to choose a gpx file that was recorded on the road trip that the photo was taken on. Once the program has read the tracklog, you will see a map showing the gpx tracklog. Any images that were taken at a time not within the tracklog will be flagged.
Step 3. Click the 'Place Images' button. A 'pin' will be shown on the map where the picture was linked to the tracklog location
Step 4. Confirm the placement, zoom in, adjust the time sliders if required. Click the 'Done' button
Step 5. Save the images with the geotagged data. The File menu has a couple of options allowing you to save selected, save all, or export.
Note - After Step 4, you can click on the 'Get Location Text' button and the program will do a lookup and return additional information like the Region and Country which is also inserted into the EXIF metadata. In the above example it returned 'Canterbury' and 'New Zealand'. Very cool!
Once Geotagged, the location the photo was taken is available for use:
- The photo sharing group Flickr has specific geotagged information it shows with tagged images
- Panoramio is a geotagged photo search engine - interfaced with Google Earth
- Google Earth and Google Picasa also use geotagged images
- And future generations will be able to tell where a photo was taken, without having to resort to scratchy memory recall!
Now you can see where the photo was taken!