"GPS Image Direction" is set to an incorrect value

[kudarisenmon]

Basic information

• Release version: 0.5.3
• System: Linux
• Capture Device: Action Camera | GoPro HERO3 | Garmin Logger

Steps to reproduce behavior

1. 0.5 seconds time lapse shooting with the GoPro HERO3 (GoPro HERO3 doesn't have a built-in GPS).
2. Record the location with the Garmin GPS logger.
3. Add "GPS Image Direction" to the Exif with the following command.
   mapillary_tools process_and_upload --advanced --user_name kudarisenmon --geotag_source "gpx" --local_time --interpolate_directions --overwrite_EXIF_direction_tag --overwrite_EXIF_gps_tag --geotag_source_path 2020-02-11.gpx --import_path /media/DCIM

Expected behavior

All photos will have the correct Exif "GPS Image Direction" tag embedded in them
As a result, the value of "MAPCompassHeading" in "Image Description" is also correct.

Actual behavior

One out of two, "GPS Image Direction" is set to an incorrect value (0).
"MAPCompassHeading" in "Image Description" is not correct.

Corresponding data

One in two isn't right because the time lapse is 0.5 seconds.

• sample Sequence key
  YEAlqO5djLS5a9ZH31H1sg

https://www.mapillary.com/map/im/waM3T8xr0jMpl6NMMidO8A

• correct direction
  
• incorect direction
  

[arocoun]

Is it possible that your GPS logger only records locations in full-second intervals? In that case, half the images would overlap. Then, when overlapping images have their directions interpolated, half of them will point in some random direction in an attempt to point at the same spot they're on.

I bring this up because I once took photos at 0.5 second intervals with my phone, and about 15% of them had duplicate GPS info because GPS didn't update rapidly enough. Your solution may be to take photos at slower intervals, or find a way to get your GPS coordinates to update more rapidly.