Tuesday, February 9, 2010

Geotagging

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.

Happy Geotagging!

12 comments:

  1. Great post! Sometimes before I visit a place, I'll look it up on a Flickr map to see the photos that were taken there. Neat way to find places to go.

    Now that you have a GPS, have you tried Geocaching? It's like a scavenger hunt! I really like the ones where you have to solve riddles too.

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  2. Thanks Andrew. I haven't tried Geocaching yet although I've read about it. Sounds like fun!

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  3. Interesting Mick. I assume you have to tell the GPS unit somehow when you have taken a photo. Marked as a waypoint?

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  4. Hi John, no waypoints or marks necessary - that's the beauty of it I think! The track is time stamped within the unit and those times are used to synch with the photos. I turned the GPS unit on as i started walking - put it in my pocket - and didn't touch it again until I had finished my walk and was going home - then just saved the track and turned it off.

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  5. Ah. I assume that is why the time in the camera and the GPS have to match. I guess the computer program takes the time from the photo and finds the GPS reading made at that time. Very cunning ;)

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  6. Hi again John - yes very clever and certainly much easier than marking every point at which you take a photo.

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  7. Hi Mick
    .
    I do not have a GPS.
    .
    I would be reluctant to tell orchid thieves exactly where they might find rare plants.
    Not a problem with your waders, I acknowledge.
    .
    Cheers
    Denis

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  8. Hi Denis, of course it's not necessary to pass on GPS data. But I like the idea of relying only on your memory!

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  9. If you have no GPS data logger but you do have an iPhone take a look at my iPhone app GeoLogTag. It turns the iPhone into a GPS data logger and depending on where you manage your photos, it also geotags the photos (Mac & Flickr).

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  10. Hi Chris, I am aware of such apps but not all of us have IPhones!

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  11. Hi Mick. Interesting post - I have a GPS but never thought of tagging my photos. I may give it a go next time

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  12. Hi Tony, it's so easy to tag a whole series of photos together - wish I had worked this all out earlier.

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