Offsetting time for GoPro Max

Contributing and equipment Command line tools
1

My GoPro Max has excellent GPS, I’m finding! The paths the sequences go along are far more accurate than what my phone’s GPS can create.

But with 360° time lapse photos, it misplaces images about a full second ahead of where they were taken.

I use the following command:

mapillary_tools process --import_path Trip1 --cutoff_time 10 --duplicate_distance 1.5 --duplicate_angle 360 --interpolate_directions --offset_angle 0 --overwrite_EXIF_direction_tag --user_name jesseakaraccoon --advanced

I get a situation that looks like this:

Sequence: >==A=====a===B======b===C==>

Where A and B are the ACTUAL photo positions, and a and b are what their geotag says, and thus where they show up on mapillary, too far ahead. At faster speeds, this can be a difference of over 10 meters!

What additional commands or subprocesses can you suggest to correct this?

EDIT: Turns out the solution is exactly as simple as adding “–offset_time 1” to the command. It then looks like:

mapillary_tools process --import_path Trip1 --cutoff_time 10 --duplicate_distance 1.5 --duplicate_angle 360 --interpolate_directions --offset_angle 0 --offset_time 1 --overwrite_EXIF_direction_tag --user_name jesseakaraccoon --advanced

I’ll just leave this here, since the official readme is kinda lacking in real-world explanations of offset time. I was afraid I’d have to, like, create a GPX file, since the ONLY examples the readme gives for offset time involve a GPX file.

3 Likes
2

Hi,

I’ve been trying to use --offset_time 1 to correct the GPS position of my Gopro MAX photos, but whenever I run the process command and offset the time, I open the photos in JOSM and they are still at the exact same position. Do you have an updated workflow that addresses this issue?

I’m using mapillary_tools 0.10.0a on Linux Mint 21.

3

Since v0.8, the process command does not modify the original images by default (it should be called “extract” instead TBH).

To overwrite EXIF tags, use “process --overwrite_EXIF_time_tag”, or “process --overwrite_all_EXIF_tags”.

5

I’ve been using the interpolation_offset_time flag to move my geotags. If you need the updated geotag in the metadata, you have to do what @tao said and pass the --overwrite_EXIF_gps_tag flag.

–interpolation_offset_time INTERPOLATION_OFFSET_TIME
Time offset, in seconds, that will be added for GPX interpolation, which affects image
locations. Note that it is applied after --interpolation_use_gpx_start_time. Only works for
geotagging from gpx, gopro_videos, nmea, blackvue_videos, camm. [default 0.0]

–offset_time OFFSET_TIME
Time offset, in seconds, that will be added to your image timestamps after
geotagging/interpolation. [default: 0.0]