Geo-tagging videos and photographs

Synchronizing Video Footages with Mission Planner log

If you are using a GoPro camera, or any non-GPS-enabled video camera, you can use the web service, GPS4Sport.com to synchronize your video (must be uploaded to youtube or other video-hosting websites) with your APM log (in GPX format). GPS4Sport then displays an animation of your flight in Google Earth in your browser with an insert showing the synchronized video footage. Playback requires Google Earth Plug-in to be installed in your browser. This service is free for now,and relatively user friendly.

Click on the image below for an example of a Google Earth-synchronized video of our orangutan nest hunt in Sumatra.

gps4sport

Synchronizing Photographs with Mission Planner log

Although we use GPS-enabled cameras for our drone missions (see Sensors), the GPS data logged by consumer-level cameras might not be as precise as those logged by the APM. Fortunately, the Mission Planner contains a hidden function for geo-tagging aerial photographs using GPS data logged by the APM. Here I describe how to use this function.

  1. Select the aerial photographs you wish to geotagged and put them in a new folder.
  2. Also put the “.txt” APM log file for that same mission in the same folder. (Note that this “.txt” log file is not from the telemetry. You’d have to download it from the APM to your laptop via the Terminal screen of the Mission Planner.)
  3. On the “Flight Data” page of the Mission Planner, hit Ctrl-F. This brings up a window with several hidden functions.
  4. Click on “Geo ref images”. This brings up a new window for this function. See image above.
  5. Use the button to browse to the “.txt” log file. Also browse to the Directory (folder) where the pictures are located. If your Canon camera was on GPS time during the mission, then there would be no need to specify a time offset. Otherwise to calculate time offset between GPS time and camera time, take a picture of a GPS-corrected clock with your camera (e.g., time display on a handheld GPS). For example, if your camera time is 5 seconds behind GPS time, then you should enter “-5” in the time offset box.
  6. Hit the “Do it” button. This creates a series of 5 new files in the picture folder, including a KML, a GPX, and three text files containing the new 3D coordinates of each picture. For example, this is what you’d see in the file “location.tel”.
  7. To actually stamp the APM’s coordinate info onto the EXIF data of your photographs, you need to click on “GeoTag Images”. This creates a duplicate set of pictures, each with a suffix “_geotag”, containing the new 3D coordinates from the APM log.

For more detailed information, please refer to the APM guide for geo-tagging images.