All About Digital Photos
 
Geotagging Digital Photos

Do you know exactly where that beautiful digital photo was taken? You (and everyone else) can know this forever if you put in the location co-ordinates (geographically encode) into your digital photos. The EXIF header (the photographic information header of a digital photo) has the ability to record the latitude, longitude, altitude and the facing direction of the photo. It's still somewhat early days for geotagging, and the caveats that I've posted about IPTC/XMP digital labelling information apply; not all software supports geographic co-ordinates in the EXIF header, and some will in fact strip it out. Software that I have mentioned on this site, such as Breezebrowser and Adobe Photoshop, do support it. However, like IPTC, test it with your favourite photo editing software to make sure any geotagging survives photo editing.

Many compact cameras and smartphones come with GPS built in but it should be noted that these tend to be slow (long time to get a lock) and inaccurate (they don't have the antenna capability and processing power of a dedicated GPS unit). So treat the co-ordinates they deliver with a grain of salt. As of this writing, most higher end cameras (digital SLRs) don't have built in GPS, the techniques listed below will help you obtain accurate GPS data for your photos.

I'm not going to get into a detailed tutorial on the topic, there are many other sites on the internet that conver this topic in detail. I'll just introduce the concepts.

Manual, Automatic, GPS, no GPS

You don't need a GPS (Geographic Positioning System device) to geotag photos, but if you do have one it opens up more possibilities.

Manual, no GPS: You can use a paper map to obtain the geographic co-ordinates of the location that you've photographed. Most countries offer detailed topographic maps with latitude and longitude marked on them. However a much easier and free method is to use Google Earth to obtain the co-ordinates. This works best in areas of detailed satellite coverage. Google Earth continually improves the detail of their database, so if your area doesn't yet have detailed coverage, it should in the next few years. Co-ordinates obtained can be manually recorded and then entered into the photo (see Software below).

Automatic, no GPS: Automatic co-ordinate entry can be done through the latest version of Picasa and Google Earth. It simply involves choosing the photo(s) in Picasa andselecting the "Tools > Geotag > Geotag with Google Earth" option, select the location in Google Earth, then press the "geotag" button to write those co-ordinates to your selected photo(s). Very easy.

Manual, GPS: If you have a GPS unit, you can manually record the location of each photo by simply marking a "waypoint" (most GPS units support waypoints). At the end of the day, match your waypoints to your photos and manually transfer the data (see Software below). If you are in a car that has a GPS in it, some can mark a co-ordinate (i.e. "Where am I"), check the manual for this type of function.

Automatic, GPS: This is the fastest, simplest way to batch geotag photos. You'll need a GPS unit that can record a "track log" and dump that track log to a computer. You'll need software that can match that track log to your photos. The software (see Software below) does this by matching the time stamps of the track log to that of your photos. So, the main thing you have to remember is to check the time setting on your camera to make sure it is accurate (the GPS automatically gets the time from the satellites it monitors). Purists will match the time on the camera to that shown on the GPS unit.

Another point to remember is that what you're really getting in terms of co-ordinates is the position of the GPS unit when you took the photo. If you're carrying the GPS unit, this will then be your position (not the position of the subject of your photo), which is accurate enough for many people (it's the "point of view" of the photo). Those striving for more accuracy will have the foresight to (if possible) put the GPS near the subject of the photo.

One final note here is that most GPS unit take track log readings at specified intervals (i.e. every 30 seconds) - check this and adjust to your needs before you start. For optimal accuracy, leave the GPS unit in place for at least two of those intervals (wait one interval, take the photo, wait for the next before moving the GPS).

Software

I'm only going to mention four products here. For casual use (and if you're already using it for other reasons such as I am), Breezebrowser Pro (www.breezesys.com) does manual geotagging or can use a GPS tracklog.

Picasa (picasa.google.com) is a good geotagging option since it is free and can do easy geotagging using Google Earth.

If you use a GPS that generates a tracklog, then a good companion program is RoboGeo (www.robogeo.com), an inexpensive piece of software directly made for geotagging. It will allow you to do all your geotagging (automatic using GPS track logs, manual entry or Google Earth). Despite the complexity of what it's doing, Robogeo seems well designed and easy to use. Best thing is to download the demo and try it out (note that the demo version deliberately changes the co-ordinates a bit).


Another geotagging program is Geosetter (www.geosetter.de), a freeware program that will let you apply and display geotags.

Happy Geotagging!!



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