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andreynovikov / trekarta

Simple, responsive map for your trek. You decide how to journey today, not the application!
https://trekarta.info
GNU General Public License v3.0
175 stars 25 forks source link

GPS altitude #76

Closed hungerburg closed 4 years ago

hungerburg commented 5 years ago

Toying around in Trekarta, I find the reported elevation (in the extended info box left hand, and in recorded traks) consistently about 50 m too high. The "GPS-Test" app shows a much better match. This is with a Mediatek SOC and also with hillshades, just in case, that matters. Is that a bug?

hungerburg commented 5 years ago

I guess, I have found a bug. On a place with altitude known from local governmental GIS, Trekarta elevation is off by ~50m; EGM96 for this very location is ~48m.

To me, that looks like Trekarta does its own Geoid corrections on system readings, which already are corrected. If system values depend on OEM device configuration or android version, Geoid corrections should be configurable in preferences.

andreynovikov commented 4 years ago

Previously Android didn't apply geoid correction to altitude. Looks like modern versions do it. I will remove it from Trekarta.

ulipo commented 3 months ago

I resume this old issue as I noticed the same behaviour on v. 2024.03.22, see attached screenshot with split screen. Screenshot_2024-06-01-17-57-55-00_0692018f22614dd5789e3464f05cf011