Altitude profile and gain based on map altitude data

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marcs
Posts: 58
Joined: Sun Aug 02, 2015 3:58 pm

Altitude profile and gain based on map altitude data

Post by marcs » Sun Feb 16, 2020 8:56 pm

Hello,
When I record a path the altitude from the GPS is noisy and I often get spikes in the altitude even if the xy position looks correct.
As a consequence the computed altitude gain/loss are wrong.
Is it possible to compute the altitude profile and gain/loss based on the altitude data obtained from the map instead of from the gps ?

Alpinequest is a great app, the first I install and test when I need to change phone ! It works fine on my new Xiaomi Mi 9T.

Psyberia-Support
Site Admin
Posts: 4895
Joined: Wed Apr 14, 2010 9:41 pm

Re: Altitude profile and gain based on map altitude data

Post by Psyberia-Support » Tue Feb 18, 2020 6:19 pm

Hi,
The a track does contain elevation data, then the application will use it, there is currently no way to do differently. If you track is very noisy, you can increase the "Noise reduction" in the stats setting. Alternatively you can click on your displayed track, and select "Edit profile" to remove the erroneous points.
I'll see if and how I can add a setting to override the track elevation, but honestly I don't know when I'll have time (the waiting list grows much too fast those days).
Do you like AlpineQuest ? Leave a small comment on Google Play !

marcs
Posts: 58
Joined: Sun Aug 02, 2015 3:58 pm

Re: Altitude profile and gain based on map altitude data

Post by marcs » Sun Mar 08, 2020 8:48 am

Hi,
I think it would be a really nice feature given the lack of vertical accuracy of gps data.

On my device I sometimes get altitude "jumps" of 50 to 200 meters which are too big to filter. I checked recorded data in one example: 200 m jump from one measurement to the next, and then it takes about 20 seconds to come back to the correct value (with period set to 1s). AQ recorded gps accuracy was 13 meters max. Peak speed was 376 km/h (I'm a fast skier !!). There does not seem to be any error in the horizontal position. During the 6 hours record, max accuracy was 17 meters.

I read that there is also a vertical accuracy value provided by the Android gps function. Is it used by Alpinequest ?
Any suggestion to suppress or filter this behaviour ?

Thanks

Psyberia-Support
Site Admin
Posts: 4895
Joined: Wed Apr 14, 2010 9:41 pm

Re: Altitude profile and gain based on map altitude data

Post by Psyberia-Support » Mon Mar 09, 2020 12:34 pm

Hi again,
The vertical accuracy is available from Android 8, but right now it's not used by AQ.

If you have big spikes in your elevation profile, you can manually clear them using the "Edit profile" tool as explained previously, right now it's the only way.
Do you like AlpineQuest ? Leave a small comment on Google Play !

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