V5.1.0 - 462 New altitude/heading shows incorrect Data

[Reinhard Punz]

Note: The displayed altitude is approximately 50 meters too high. Sometimes only 45 meters.

[Mzokk]

Standard GPS satellites don’t track your height from the actual ground (valleys, mountains). They measure your distance from a theoretical, mathematical model of the Earth called an ellipsoid. Your phone then has to translate that to "Mean Sea Level" using a gravity model, which can easily throw off calculations by hundreds of feet. In short your phone is not that accurate on the vertical plane. Even specific GPS devices such as Garmin are only accurate to +/- 30m unless they also take data from a topographic database which triangulates horizontal position with a topographical datum. My phone is a 60m out using MRA or OSMand (reading high) and my Zumo XT usually under or over reads by 20-30m

[Mzokk]

Oh and strangely it can be accurate at higher elevations. I was using MRA on a trip on Saturday crossing a pass at 448m and it was reading 447M passing the datum point??

[Mzokk]

I did a little experiment with this. My house is just below a 50m contour line. My phone using MRA gives 341ft or 104M.

Same with OSMand.

In OSMand you can download a correction file "World Altitude Correction"

This puts me at 157ft or 48M which would be within + or - 3m of my actual elevation.

Might be worth building in the correction file somewhere?

[Jörgen]

I noticed also that a correction of about -50 m is necessary.

[Jörgen]

Regarding the Noth segment display, I believe it was always correct.

[Guzzist]

I compared several apps and GPX Tools. Only OsmAnd Shows the correct value (at my home base in southern part of Germany.

[Rob Verhoeff]

It’s just a nice extra feature! It’s not like your life depends on the altitude display shown by the navigation system. I see it as a fun gimmick. Whether I’m driving at sea level or at 1500 meters in mountainous terrain, it’s simply fun to see — nothing more. And I believe that’s exactly how this functionality was intended: nothing more and nothing less. Apparently, some phones handle it better than others.

[Guzzist]

@Rob-Verhoeff I totally agree with you Rob. It was just this discussion, which let me check just at home, because I know the hight there

[Mzokk]

@Rob-Verhoeff Agree also. Just a fun thing. Elevation isn't even critical when hill walking. I'm more of a map and old Silva compass person for that activity. I have started to use OSMand a bit whilst walking.......its a slippery slope (sorry couldn't resist)

[Bouke Ent]

In The Netherlands our level is based on NAP. GPS level is based on a globel level. for yhe netherlands it is arround a 40 meter differance then our NAP.