Wrong time offset, only with some files

[feklee]

Applies to: Version 13.18 (x86_64, Qt 6.6.1)

Have a look at the following tracks. Both were recorded with GPSLogger on Android while in Japan.

• 20231211.gpx.gz: All good, times are correctly shown in the local Japanese time zone UTC+09. According to what I see in GPXSee, I start moving around 8:00, which is plausible.

• 20231212.gpx.gz: According to GPXSee, GPS tracking starts at midnight, and I head out around 1:30 in the morning. This is incorrect. Garmin BaseCamp and Google Earth Pro both report the start of the GPS tracking at 7:33.

Is this an issue with GPXSee?

In the files themselves I cannot see anything special. Not sure if this is even a time zone issue. It looks like GPXSee simply moves the first time in the file to midnight.

PS: Downloading this version from SourceForge took more than 2 hours. I tried from Indonesia, from the UK, and from Finland.

[tumic0]

I have investigated the files and the "problem" is not in the time/timezone. Your tracks are a combination of a car ride and a walk and this does not work very well with the outlier elimination algorithm. If you disable outlier elimination in the Options (Data->Filtering->Eliminate GPS outliers) then you will get a much "cleaner" path and the times will be as expected.

And by the way, thank's for the donation :-)

[feklee]

Your tracks are a combination of a car ride and a walk and this does not work very well with the outlier elimination algorithm.

Thank you for pointing that out! I will keep this option disabled as I generally use multi-mode transportation. In this case it was walking plus using train, metro, and taxi.

However, the problem with the offset did not go away. See my photo DSC_0361.JPG.gz. I took that with my phone at 12:05:47, stopping at a shop window when walking. Yet, according to GPXSee, I was near that location at 03:32:06:

[tumic0]

03:32:06 is the relative time from the track start. If you want the absolute time, you can enable it under Data->Position Info->Date/time (it will be shown next to the position marker on the map).

[feklee]

Thank you, that explains it all!

For most of my GPX files, the relative time is equal to the absolute time, simply because the app that I use for tracking on my phone starts a new track at midnight. Occasionally, my phone is turned off at midnight. This when I get the “offset”, which isn’t an offset after all.