Jamie Thingelstad's personal website

GPS Track Rant

Why is it that almost all GPS units decide that when you save your active track into memory that they should degrade functionality? Yes, it is true. Nearly all GPS units upon saving do two things. First, they discard the time and date information from the track. Secondly, they remove “unnecessary” points from the track, sort of smoothing it out. This reduces the size of the saved track.

The second item, removing “unnecessary” points isn’t entirely evil, but I do question it. However, removing the time and date stamp upon saving is terribly evil!

I went back into my saved GPS tracks to do some geo-association with photos from Switzerland and the matching program came up with a big clueless expression. The time and dates are all gone. Ugh!

I’m left with only one decent option, writing a program that will associate known times with some number of points in the track and then interpolate the remaining times. Sigh…


  1. Interesting. Not all GPS units to that. For example Garmin watches keep the locations and time and can be used to plot a workout against time and heart rate with certain models.

  2. To clarify, the only time it drops the time data is when you save the “active tracks” into a saved track file. I’m guessing that the watches don’t have the ability to save tracks into memory permanently and thus it isn’t applicable?

    The time data is never lost for the “active track”, but the problem with that is only so much information can be kept in the active track.

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