In this post Colin Spencer gives us a good introduction to how to Geotag images. You can see some of Colin’s images here and learn more about him at the conclusion of this article.
I was recently reading about the geotagging of photographs’ and decided that I would investigate it further and if appropriate try it for myself.
What is Geotagging?
Geotagging is the recording of the latitude and longitude of the location where a photograph was taken and then the addition of this data to the EXIF information that was captured by the camera when the photograph was taken. The EXIF data is recorded within the digital image file that the camera records and this data can be read by any suitable software.
How do I Geotag an Image?
There are two ways to Geotag an image, the first is by looking at a map and working out exactly where the photograph was taken and then entering the information manually into the photograph.
The second is to use a GPS to log the location of the photograph and then add that information either automatically or manually to the EXIF data. Some digital cameras are now coming equipped with a GPS to record this data automatically and others allow the fitting of a special GPS receiver to the flash hot shoe and then they communicate the data to the camera usually by an additional cable connection. Alternatively the GPS and camera can be independent and the location data can be added later by software. This is the method I decided to explore.
What equipment do I need for Geotagging?
You will need a GPS that records ‘track data’, a cable to connect your GPS to your computer and a digital camera and some suitable software. I will detail the software that I used later in this article.
What equipment did you use for Geotagging?
I used an old Garmin GPS12 that I had as a spare hand held GPS from when I had a boat and a Canon EOS 20D.
How did you make it all work?
For this test I just took my camera and a 17-70mm lens and the Garmin GPS. Before I left home I made sure the GPS was working and checked the time that it was displaying from the GPS satellites. I then adjusted the time on my camera to match the GPS time. This is critical to ensure that when a photograph is recorded by the camera that the GPS knows where you are as the software uses the time the photograph was taken to match up with the GPS position at that time. Depending on the settings of your GPS this can cause a problem (more on this later).
As I left home I turned the GPS on and put it in my camera bag. I then put the camera bag in the pannier of my motorcycle. I then went out for a 30km ride and stopped a few times along the way to take some photographs. When I got back home I turned the GPS off.
I downloaded all my photographs onto my PC and then converted them all from RAW to JPEG images. I did no editing to them as this was just a trial to ensure that everything worked. The reason for converting to JPEG is that most of the automatic geotagging software will not tag RAW images and rightly so too I do not want any software writing to my RAW images.
The next job was to download the track data from my GPS. The software that I used was EasyGPS available from http://www.easygps.com/ and it is a free piece of software. I downloaded the track and saved it as a .gpx file which is one of the formats that the geotagging software I used wanted.
Once the track data was saved it was then time to start geotagging. The software that I used for this was GPicSync and that is available free from http://code.google.com/p/gpicsync/. I opened up GPicSync and entered the file locations into the appropriate places as shown here.
I had a problem at this point as mentioned above the track would not sync with the photographs that I had taken as there were no photographs taken within 300 seconds of any of the track points. It took me a while to realise that even though in my GPS setup I had corrected the time to my local time (+2 hours to UTC) the actual track point time recorded by the GPS was the UTC time not the adjusted time. This might be a foible of my Garmin GPS but it is something to be aware of. Once I entered +2 into the UTC offset box the photos and the track points synchronised perfectly.
Something very important to note here is the GPicSync will take a backup of your images before it alters them if you tick the appropriate box as above. By default this box is ticked.
The next screen shot shows GPicSync synchronising the locations and the photographs.
Once GPicSync had finished synchronising the data I pressed the ‘view in Google Earth’ button and this is a screenshot of what was displayed.
The route that I took is shown in blue and the photographs that I took are shown as small thumbnails at the location that I took them.
This screenshot shows a zoomed in view of the map with the photographs as larger thumbnails.
To the left hand side of this screenshot there are several blue and white dots. These show the location of photographs taken by other people who have uploaded them by location to Panoramio. The Panoramio website is at http://www.panoramio.com. This next screenshot shows what happens if you click on one of these dots (that become camera icons if you zoom in closer).
GPicSync saves this Google Earth image as a .kml file in the same directory as your photographs so that you can return to this view direct at anytime providing that you have Google Earth installed on your computer. It has also saved the location information and more into the EXIF data of the photograph and this can now be viewed with any EXIF data reader software. I use Photome another free piece of software from http://www.photome.de/. This next screenshot shows Photome displaying the IPTC data from within the EXIF of one of these photographs.
Here it has put meaningful place data as well as the latitude and longitude. This next screenshot shows Photome just displaying the relevant location data in the GPS section of the EXIF data.
What do I do with this additional information in my photograph?
Now that your photograph has this data in it if you upload it to Panoramio or Flickr for example they will make use of the location data for the display of where in the world that your photograph was taken. I am sure that other photo sites make use of this data too but these are the two I am familiar with. You could also use the Google Earth file to bore your friends and family with additional information about your photography.
My thanks go out to all the software authors mentioned in this article for their altruism in allowing us to use their software free of charge.
If you wish to contact me about this article please email me at colinsp@freeuk.co.uk and include Geotagging as the subject in your email.
Colin Spencer was born in the UK and took early retirement and now live in Spain. He is an amateur photographer and enjoy photographing a variety of subjects – some of his photographs can be seen at http://photos.turnspain.com and a pdf of this geotagging document can be downloaded from http://www.macameraclub.com/Geotagging.pdf.
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