Elevation Correction

by pkan

Downloads: 64,344 (30) • Reviews: 11

Version:

1.9

Updated:

Nov 29, 2017

Elevation Correction Bugs

Elevation Correction Bugs

Postby like-to-tri » Wed Sep 01, 2010 8:39 am

The elevation correction plugin is stopping the display of (or removing) the uncorrected elevation information and is also giving inconsistent results.

Here's a sample of the behavior:

1) I have a .TCX file (they all seem to have this behavior) that when imported into ST with the Elevation Correction Plugin unchecked, produces 'Climb: +2,859 / -2,352'.
2) When this .TCX file is imported into ST with the Elevation Correction Plugin checked, it produces 'Climb: +3,664 / -3,609'.
3) If I now click on Edit->Undo elevation correction, I get: 'Climb: 0 / 0'
4) Now clicking on Edit->Apply elevation correction, I get: 'Climb: +3,129 / -3,027'

Notice that both the undone elevation is zero (#3) and also that the reapplied elevation correction (#4) doesn't match the initially corrected elevation.

I have used the Elevation Correction Plugin for 1-2 years before this time, and never had these problems.

SportTracks 3.0.3886
Elevation Correction Plugin 1.6.0
GDAL plugin 1.1.3.17
like-to-tri
 
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Postby pkan » Wed Sep 01, 2010 1:21 pm

I've investigated this using a .TCX file provided by like-to-tri, and it turns out that the problem is caused by the first trackpoint not having any elevation data, i.e., no AltitudeMeters XML element. GPS points with no elevation data are not properly handled by the plugin when saving the original elevation data, and the result is that the original elevation data is lost. This is why Edit->Undo gives Climb 0/0 (and an empty elevation graph). I'm not sure why you get different results from a second Edit->Apply. I can't reproduce it. You could try exporting to .fitlog after the first and second correction. Comparing the fitlogs should provide some clues.

Anyway, I will add a fix to handle GPS trackpoints with no elevation data. Until the new version is released my advice would be to avoid applying elevation correction to data from units which behave this way if you care about preserving the original elevation data.
pkan
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