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Understanding data in TCX file

Former Member over 11 years ago

Hello all,

I'm hoping someone else out there has looked into the syntax of the TCX data files (really just XML files) and can answer a specific question for me. From what I see, the data structure (and explanation) could be like so:

an Activity is one complete run/bike/swim,
each Activity has many Laps,
each Lap has many Tracks, and
each Track has many Trackpoints

This all makes pretty good sense to me. What doesn't make sense to me is that the very first Trackpoint seems to match up with the start of the Activity (based on timestamp), yet it also has a distance (expressed in the DistanceMeters property). How is that possible?

From what I could tell, the DistanceMeters attribute of a Trackpoint is calculated based on the distance between the longitude and latitude of the current Trackpoint to the longitude and latitude of the previous Trackpoint. On the very first Trackpoint, there's nothing to compare it to in order to do the calculation.

So, do I have this right? Is the first Trackpoint really the beginning point of the run, then the 2nd trackpoint and all others after use it as the beginning? If so, should I ignore the DistanceMeters of Trackpoint number 1?

Thanks,
SMB

0 ISLUPEPA over 9 years ago

Hello all,

I'm hoping someone else out there has looked into the syntax of the TCX data files (really just XML files) and can answer a specific question for me. From what I see, the data structure (and explanation) could be like so:

an Activity is one complete run/bike/swim,
each Activity has many Laps,
each Lap has many Tracks, and
each Track has many Trackpoints

This all makes pretty good sense to me. What doesn't make sense to me is that the very first Trackpoint seems to match up with the start of the Activity (based on timestamp), yet it also has a distance (expressed in the DistanceMeters property). How is that possible?

From what I could tell, the DistanceMeters attribute of a Trackpoint is calculated based on the distance between the longitude and latitude of the current Trackpoint to the longitude and latitude of the previous Trackpoint. On the very first Trackpoint, there's nothing to compare it to in order to do the calculation.

So, do I have this right? Is the first Trackpoint really the beginning point of the run, then the 2nd trackpoint and all others after use it as the beginning? If so, should I ignore the DistanceMeters of Trackpoint number 1?

Thanks,
SMB

I am also trying to find an answer to this question.
Thanks,

Per

0 jimrward269 over 9 years ago

without seeing your file, just out of curiosity, does the last track point have a distance value, maybe it writes one behind, as some sort of fail safe should power be lost or corruption

i will have a look at some of the files for my 705

0 ISLUPEPA over 9 years ago

without seeing your file, just out of curiosity, does the last track point have a distance value, maybe it writes one behind, as some sort of fail safe should power be lost or corruption

i will have a look at some of the files for my 705

Yes, the last track point has also a distance value.