Geotag GoPro Images with a Pixhawk Log File

Overview

To add geotags to your GoPro images you'll need to set your GoPro's time to GPS time, setup and fly a mission with your Pixhawk based UAV while taking pictures with your GoPro, then add geotags to your images using Mission Planner.

Set your GoPro time to GPS time

The minutes and seconds on your phone time are automatically synched to GPS time. Do the following to synch your GoPro's minutes and seconds to GPS time.

  1. Install GoPro's phone app.
  2. Use GoPro's documentation to pair your phone and GoPro.

  3.  
  4. In the GoPro app, select Settings > Set Date and Time to synch your GoPro to your phone's time.

Setup and fly a mission

  1. Make sure LOG_BITMASK is set to 655358. This will make your Pixhawk record CAM trigger messages in its log file. You'll use the messages to help determine the hour difference of your GoPro and GPS time.

  2.  
  3. Create your flight grid and add a DO_SET_CAM_TRIGG_DIST command. Set to 20 meters. This is just for writing a CAM message to your Pixhawk log file, not for actually triggering your GoPro.
  4. Set your GoPro to Time Lapse mode, take a picture about every two seconds and fly your mission.

Add geotags using Mission Planner

  1. Create a folder on your PC and copy the .bin file from your mission off your Pixhawk SD card.
  2. Start Mission Planner > Flight Data > DataFlash Logs tab > PX4 bin to log. Load your .bin file and save it as a .log file.
  3. Copy your pictures from your GoPro to the new folder with your log file.
  4. In Mission Planner select Control + F.
  5. Select Geo ref images.
  6. Select Browse Log and and select your .log file.
  7. Select Browse Pictures and select your pictures.

  8.  
  9. Select Time offset, then Estimate Offset. This example shows an offset of -17988.4. This is the difference between the time the Pixhawk recorded its first camera trigger message and the time stamp on the first picture. This number is not accurate since the GoPro was taking pictures before the UAV even took off, but it lets us know what number to use based on the time zone difference. Minutes and seconds on the image timestamps are already accurate, we just need to know how many hours to offset in seconds. There are 3600 seconds per hour. 5 hours offset is 18000. The real number we need for Seconds Offset is (negative) -18000.
  10. Hours Seconds
    1 3600
    2 7200
    23 82800

  11. Enter your corrected offset in the Seconds offset box and press the Pre-Process button. 
  12. Press the GeoTag Images button.
  13. Your geotagged images will be added to a new folder named geotagged inside the folder with the photos.