Interpolating missing timestamps in GPS track

Question

I have two tracks from a recent outing. One is a detailed representation of the route without timestamps (derived from a map), and the other is a coarse GPS track (a point every 5 to 15 minutes or so) with timestamps.

I have combined them into a single track where each track point corresponding with the coarse GPS track has a timestamp (including the first and last), while the rest do not. (That is to say, only some of the <trkpt> elements have a <time> element in the GPX file).

I'd like to attach timestamps to the remaining points by interpolating between the ones that current have timestamps, taking distance into account, and writing a new .gpx file with the interpolated timestamps.

Is there a tool that would allow me to accomplish this in a straightforward way?

I've found tools that will let one interpolate times for a whole track with no timestamps by specifying a start and end time, and even a tool (Linetime) where one can specify some “keytimes” manually along the way, but none that can take a track with some timestamps already filled in and interpolate the rest based on that.

Hoping for an open source tool that I can use from Linux. Command-line or GUI is fine.

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This is distinct from Seeking tool to manipulate timestamps in GPX file, which is specifically about tools to add timestamps to a track with no existing timestamps by specifying just a start and end time, and the answers are geared toward that specific task. As I mentioned above, I had already come across several such tools myself. This question is looking for a tool that can take a track where some track points have timestamps and others do not throughout the file, and interpolate and fill in the missing timestamps based on the present ones.

Even if one of the tools there can do both tasks, they are still distinct tasks, and most of the tools mentioned there cannot solve this one, so it would be nice to have this question with suggestions and instructions for solving this specific task. (The only tool mentioned there that sounds like it may be able to handle this task is EditGPX, a French-language, web based tool, with no instructions given there for usage for either task. I would prefer an offline tool I can run from Linux.)

Answer 1

GPS-Utility did the job for me, [GPS-Utility][1] [1]: https://www.gpsu.co.uk/

Opening the GPX file will will correct the missing tags by copying over the last known value to the all subsequent trackpoints without a timestamp.

After opening the trackpoints are shown in a Table view. The UTC-Time column will have some entrys having the exact same timestamp , these trackpoints did not have any timecode. Go to the first trackpoint having the same timecode and highlight it with the Record / Mark Highlighted command or just click the small cell right of the Trackpoint ID. Go to the first trackpoint having a different timecode and highlight it as well.

From the Tools menu, click the "Set Time between highlighted" .

You will get new timestamps according to the average speed between the to highlighted Trackpoints.