I bought a new Olympus Stylus TG-3 camera last week with. It has lots of nice features (water proof, shock proof, small, good macro photos, not terribly expensive) but possibly most interesting is the ability to track my location with GPS. It seems to embed the GPS (or other location data like "Quasi-Zenith Satellites System and GLONASS" (pdf page 70)) data in the jpeg exif data (which I wrote about as well but for the pictures from my cell phone) but also has the ability to track your location continuously regardless of taking pictures or even being powered on.
Before using the GPS I needed to update the A-GPS information using the Olympus Apps (there are two) and turn on the GPS and tracking info from the camera's menu. After riding to work and taking a few pictures I connected the camera to my computer and grabbed the GPS log files. They are stored in a GPSLOG folder on the SD card and have a .LOG file extension.
The data are stored in an NMEA file format which looks like this
$GPGGA,153232.3,4738.8924,N,12223.8371,W,1,,,,M,,M,,*55
$GPRMC,153232.3,A,4738.8924,N,12223.8371,W,,,081014,,*18
Those are the only two "sentences" that come down from my camera: $GPGGA and $GPRMC. The $GPGGA is the "Global Positioning System Fix Data" and the $GPRMC is "Recommended Minimum Specific GPS/TRANSIT Data". I'm not sure why there are both but there are.
There is a part in the intro in the gpsinformation.org site that describes how you determine the datum of that data in your file. Apparently, Magellan and Garmin will commonly use another datum and will specify what is being used by including one sentence at the top like
but
Most other units always output NMEA messages in the WGS84 datum. Be sure and check the user documentation to be sure.
In general, I guess this is a great format for recording but doesn't import well into other programs[citation needed] so I started looking at how to convert to something else.
Open Street Map has a great page about converting NMEA to GPX which says to use GPS Babel (which I had seen from a few other pages already). I downloaded, installed, and even though there are commandline tools the GUI opened right up and I had already converted my file to KML (I changed my mind about GPX though it actually worked exactly the same).
I'll just include the command for completeness
"C:\Program Files (x86)\GPSBabel\gpsbabel.exe" -i nmea -f "14100801.LOG" -o kml -F "14100801.KML"
Now this KML file imported into Arc and I know I can plot KML files into Google Earth and Google Maps.
Keeping in mind this is super inaccurate and really only cool for recreational use like taking pictures while hiking. There is not enough info included in the downloaded file to correct the GPS data or to sufficiently describe it's quality if you are really wanting to use it. I.e. the file from my camera does not specify the number of satellites in view, how good the lock is on them, the error associated with each data point. On a better GPS file there would be one line per reading per satellite. Here the camera has mashed it all up into one line.