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en:help:1.4:landmarks:statistics [2014/11/02 21:51]
alpinequest [Tracks statistics]
en:help:1.4:landmarks:statistics [2017/09/12 11:21] (current)
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 In order to compute these values, it's important to define more precisely what means "along the track"​. In order to compute these values, it's important to define more precisely what means "along the track"​.
  
-A first definition would be to take into account **the altitude differences between mountain passes and summits**. If you start a hike at +150m, climb to a summit at +500m, then go back to your start location at +150m, your gain will be 350m. In practice, trails usually don't go straight forward to the summit, but will go uphill for some time, then downhill a little bit, then uphill again, etc. This first definition doesn'​t take all these small changes into account, and will then lead to an **under-estimated gain**.+A first definition would be to only take into account **the altitude differences between mountain passes and summits**. If you start a hike at +150m, climb to a summit at +500m, then go back to your start location at +150m, your gain will be 350m. In practice, trails usually don't go straight forward to the summit, but will go uphill for some time, then downhill a little bit, then uphill again, etc. This first definition doesn'​t take all these small changes into account, and will then lead to an **under-estimated gain**.
  
 Another definition would then be to take into account **the altitude differences between all the locations that make the track**. Now imagine a track recorded with a GPS along the sea. The GPS, having an imperfect accuracy, will record altitudes of [+1m, +2m, 0m, +1m, -1m, +2m, ...]. With this small segment of 6 locations, we have a gain of +5m. With a track of 1000 locations, it would lead to a gain of more than +800m which is a very **over-estimated gain**, since the track is along a flat shoreline and should have no gain. Another definition would then be to take into account **the altitude differences between all the locations that make the track**. Now imagine a track recorded with a GPS along the sea. The GPS, having an imperfect accuracy, will record altitudes of [+1m, +2m, 0m, +1m, -1m, +2m, ...]. With this small segment of 6 locations, we have a gain of +5m. With a track of 1000 locations, it would lead to a gain of more than +800m which is a very **over-estimated gain**, since the track is along a flat shoreline and should have no gain.
  
-At then end, the "​perfect"​ gain definition would be something between these two last one. In order to compute the best gain approximation,​ the application will first remove noises from the track (including the GPS inaccuracy) to create a smoother altitude profile, and then compute the gain based on each location altitudes.+At then end, the "​perfect"​ gain definition would be something between these two ones. In order to compute the best gain approximation,​ the application will first remove noises from the track (including the GPS inaccuracy) to create a smoother altitude profile, and then compute the gain based on each location altitudes.
  
 {{:​icon_help.png?​nolink}} You can disable or increase the default noise reduction. In the statistics settings section, click on the ''"​**Edit**"''​ button {{:​icon_01.png?​nolink}},​ and change the ''"​**Noise reduction**"''​ setting {{:​icon_02.png?​nolink}}. {{:​icon_help.png?​nolink}} You can disable or increase the default noise reduction. In the statistics settings section, click on the ''"​**Edit**"''​ button {{:​icon_01.png?​nolink}},​ and change the ''"​**Noise reduction**"''​ setting {{:​icon_02.png?​nolink}}.

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