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OpenTracksApp / OpenTracks

OpenTracks is a sport tracking application that completely respects your privacy.
https://OpenTracksApp.com
Apache License 2.0
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Show gradient of uphill/downhill #955

Open vsevjednom-cz opened 3 years ago

vsevjednom-cz commented 3 years ago

Is your feature request related to a problem? Please describe. My friend has good idea: show current gradient of uphill/downhill.

Describe the solution you'd like Calculation while recording. It's similar like speed count. I'm using for calculation something like this in PHP: round(100*($altitude-$lastaltitude)/$distance) Result is 10 % for example - it's hard uphill for bike 🚲 but I love it!

Additional context Another item in customize recording layout.

dennisguse commented 3 years ago

Nice idea!

One disclaimer: absolute altitude via GPS is not that precise (contains quite some noise). It might be better to use the barometric sensor (or some combination).

The good old MyTracks contained some max/min grade, but I don't remember how this was derived - might be by PlayServices API. Could be worth checking the old code.

dennisguse commented 3 years ago

One more thing: barometric data is already relative to the previous stored location (as the counter is set to 0m on storing it).

But it may contain values for DESCENT and ASCENT at the same time as both counters are stored to track changes in both directions between stored locations/TrackPoints. And we do not store the order in which ascent/descent occurred (so far). It's more of an edge case :)

rgmf commented 3 years ago

I love this feature and it'd great to see it in OpenTracks.

It also looks a good challenge :smile:

vsevjednom-cz commented 3 years ago

Yep, altitude data via GPS are not precise I know. You can use barometric sensor of course. But my mobile phone doesn't have barometric sensor as you know from my issue #756 (gain and loss still not works 🙄). Some combination sounds good 😋!

vsevjednom-cz commented 3 years ago

I tried gradient/slope calculation in PHP. GPS elevation values are sometimes weird 🤪. Better will be check gradient/slope for current elevation versus previous 3 (or 5) values for example. It could eliminate bounces.

Like this: round(100*($altitude-$lastaltitude3)/($distance+$lastdistance1+$lastdistance2+$lastdistance3))

(I wrote this code from my mind, it makes sense I hope.)

dennisguse commented 3 years ago

@vsevjednom-cz You may take a look at https://www.gpsvisualizer.com/tutorials/elevation_gain.html They explain nicely how to filter/ smooth GPS elevation values to compute gain/ loss. And if we have gain/ loss, the gradient will available almost out of the box.