[done] Altitude Mismeasurement

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Wos
Posts: 9
Joined: Tue Aug 31, 2010 1:08 pm

[done] Altitude Mismeasurement

Post by Wos » Tue Dec 07, 2010 10:03 am

Greetings,I use Alpine Quest (Donated Version) for some time now.What i've noticed is that Altitude is NEVER correct.Sometimes it is +50Meters above what other GPS apps are displaying.

My device is HTC Hero, and i run on FroydVillain ROM 1.6.2(Android 2.2 [tested with more ROMs and problem is just the same]).Also i tried with various Radios.

Whats the problem?

Psyberia-Support
Site Admin
Posts: 4943
Joined: Wed Apr 14, 2010 9:41 pm

Re: Altitude Mismeasurement

Post by Psyberia-Support » Tue Dec 07, 2010 10:27 am

Hi Wos,
Thanks for asking your question here.

The altitude given in AlpineQuest is actually the raw GPS altitude.
This altitude differs from the altitude of topo maps because they don't use the same reference point (altitude 0). The GPS is based on a simple mathematical shape of the earth (WGS84), which define altitude 0. Topo map altitudes are based on a more precise shape of the earth (the Geoid), and both altitudes can differs up to 50m (+/-).

The GPS altitude can be corrected using altitude shift tables covering all the world, and I'll try to add this feature in AlpineQuest as soon as possible.

In the last versions of GPS Status, they added this correction of the GPS altitude. The number in parenthesis after the altitude is the elevation shift for the current GPS location.

You can get more information about altitude differences on this page.
Hope its help.

Regards
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Wos
Posts: 9
Joined: Tue Aug 31, 2010 1:08 pm

Re: Altitude Mismeasurement

Post by Wos » Tue Dec 07, 2010 12:32 pm

Nice to hear that.The other day i was at the top of mt Olympus and i was getting an error of ~50meters and couple of days ago i was in my flat @ Thessaloniki and i was getting 50-60 meters and i was on like 10-15 true altitude.Thats why i asked this question.

I hope you will be able to implement this as soon as possible, since it is one of the fundamental elements of the program.

Thanks again for the answer!

Psyberia-Support
Site Admin
Posts: 4943
Joined: Wed Apr 14, 2010 9:41 pm

Re: Altitude Mismeasurement

Post by Psyberia-Support » Tue Dec 07, 2010 12:43 pm

The question is normal and I also wondered why when I started to use my GPS's phone.
I'll try to find shift tables to adjust it in AlpineQuest, you're right that it's an important feature.
It hasn't been a priority until now cause only the display needs to be adjusted, but GPX files requires raw altitude. So all recorded data are correct. But now it's time to work on that.
I added this feature in wanted feature list.
Regards
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Wos
Posts: 9
Joined: Tue Aug 31, 2010 1:08 pm

Re: Altitude Mismeasurement

Post by Wos » Tue Dec 07, 2010 2:05 pm

Thanks again!I love Alpine Quest!! :D

Psyberia-Support
Site Admin
Posts: 4943
Joined: Wed Apr 14, 2010 9:41 pm

Re: Altitude Mismeasurement

Post by Psyberia-Support » Fri Dec 10, 2010 12:53 pm

Hi,
Altitude is now Geoid adjusted (in 1.1.2). You should get the same one than in GPS Status for example.
Moreover, when focusing a waypoint with altitude, the altitude shift is displayed between parentheses.
Regards
Do you like AlpineQuest ? Leave a small comment on Google Play !

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