Thursday 12 December 2013

Split and move GPS track segments

Some GPS devices record tracks with random errors like this:

I followed a smooth path here, the actual GPS track looks pretty irregular. To fix it you need to move every point, or just use a real GPS (instead of a smartphone "GPS" :-).

Other times your track may look something like this:

Note that the first part of the track follows the road but then it "decides" to leave the road (in reality, I never went off-road there) and then, later, it returns back on the road. To fix a problem like this one until now you had to use the "Edit points" option and move points one by one.

This is a problem people from CadenceVR had. For their product (a virtual reality cycling/training application), they need to have reliable tracks files. But when the GPS make an error like the above -- they need to fix many (thousands!) points by moving them one by one, and every move by the same few meters in the same direction.

After a few days of emailing back and forth with ideas on how to fix problems like this one, a new feature of Trackprofiler is born. You can now use the Segment editor to split segments and move them around:

How to do it...

  • Click on the track to split the segment into two new (you can merge them back later)
  • Drag the marker with the number at the start of the segment. The entire segment will move accordingly. 
  • When the segment is moved where it should have been you can merge the segments again.

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