This post is for anyone who has not yet started doing this with your photos. If you already know all about it - don't bother reading further!
Wikipedia says that "geotagging is the process of adding geographical identification to ...media such as photographs..." I have read about geotagging for some time now but have only just started using it. Now I am adding the data to my photos I can't believe it's taken me this long to get going! There will certainly be benefits to having GPS data attached to all my photos. I will now have precise location data attached to the exif data on each photo and over time can build a much more precise picture of how different species use the roosting sites.
I recently bought a Garmin etrex H handheld GPS unit. This is not a complicated unit but records tracks - which is the only thing I really need to geotag photos. Of course, the computer connection is also essential! The cables to connect to the computer are bought separately - and are very much more expensive here in Australia than they are if bought on-line.
My thanks to Matt (Neil and Kel's son) who downloaded and showed me the program he has been using to download info from a GPS unit. He has been using EasyGPS which is free software. Plug in the GPS unit to the computer and use this program to download all the information from it. Then save the track file - this will save as a GPS Exchange File (.gpx).
Matt also suggested that I try GPicSync which is a Free and Open Source Tool. This asks for two things - the folder where the photos are stored and the location of the .gpx file you have just saved. Then it synchronizes the two - and heh presto! All the photos in that folder now have GPS data written in the exif data! This is so much simpler than writing in data one photo at a time - which is what I was previously doing.
I found out last time that it's no use my posting a photo to show the GPS data in the exif as blogger strips this data off before it posts the photo. However, GPicSync also creates a Google Earth KML file and I have saved a jpg of that file. This shows exactly where I was walking out along the bay the other morning and where each photo was taken. (Click to enlarge the picture to see how icons have been entered at appropriate places.)
Now a couple of things to be careful about. Make SURE that the camera time stamp and the GPS unit's time are syncronized! Also for eastern Australia I needed to put in a UTC offset of +10 in GPicSync. Exif GPS data is written as degrees minutes and seconds - not decimal degrees so check what your GPS has been set to show.