Display / record altitude above mean sea level

[Leeb64]

I have already addressed the problem. At that time it was said that from Android 14 on the altitude would be correct.... I have an Android 15 device there now. The "altitude" is just as wrong as with the old one.. It shows 219m instead of the correct 165m. The device is a Google Pixel7.
The GPS test program shows the correct value.

[devemux86]

@Leeb64 Thanks for the report.

GPS tool apps parse the GPS data to extract the altitude, a complicated process and not battery friendly to do it constantly.

On Android 14+ we use the Android API Location.getMslAltitudeMeters with documentation:
"Returns the Mean Sea Level altitude of this location in meters."

What altitude do other users see on their devices?

[devemux86]

@Leeb64 What location service do you use, Android or Google?

[Leeb64]

OK thats the Problem! With the Android location service it works!

[devemux86]

@Leeb64 Interesting, we would expect Google service to work better.

[bios4]

What altitude do other users see on their devices?

My device (Android 14, One UI 6.1, Cruiser 5.2.1) shows an elevation of 571m, while I am at an altitude of 522m.
The value is the SAME with both location services, Android as well as Google.

I don't use the altitude display at all during navigation, but I would still like to know how this discrepancy can occur!?

[WolfgangZ42]

In Wikipedia my village is on 504 m above sea level.
Another internet source (https://coordinates-converter.com/en/altimeter) says 506 m.
The Android app GPS-Tools varies between 544 m and 563 m.
Cruiser with Google service shows 554 m.
Cruiser with Android service varies between 499 and 509.

I never use the altitude panel, knowing to sit ~0,9 m over ground is enough. 😉

[devemux86]

@Leeb64 @bios4

What do you mean correct altitude? How do you know it is the "correct"? How do you verify it?

What 2 altitudes the GPS tool programs display, normal and MSL compared to Cruiser?

[bios4]

How do you verify it?

For my part, I use the official topography data of my federal state: https://gis.stmk.gv.at/

And: I don't use any other "GPS tool", I just displayed the altitude in Cruiser out of curiosity after reading this thread...

[bios4]

Attached the different altitudes from Cruiser (same value with both location services) and from the (freshly installed) "GPS Logger" app:

[bios4]

Addendum: the "GPS Logger" app had an option "EGM96 correction" avtive when I took the above screenshot.

When I deactivate this option, also the GPS app shows an altitude of approx. 570m!

[MotoUKRider]

Samsung S20 (Android 13) running latest Cruiser and an S9 (Android 10) running one of the last v4 builds. None of the configurations (even with MSL correction in v4) will display the correct Altitude on a Panel. I am ~20m ASL at home and Cruiser displays ~60m.

OSMand on the S20 displays the Altitude correctly.

GPSTest, using the GeoID option, works just fine and has done on a variety of devices for around 15yrs.

[devemux86]

@MotoUKRider

Samsung S20 (Android 13) running latest Cruiser and an S9 (Android 10) running one of the last v4 builds. None of the configurations (even with MSL correction in v4) will display the correct Altitude on a Panel.

Cruiser 4 parsed the NMEA sentences, but this is still not reliable. The reason is explained in this Android issue:

"some apps (including GPSTest) parse the NMEA sentences provided by Android devices via the OnNmeaMessageListener to obtain the MSL altitude."

"this method is unreliable because chipset vendors often have errors (some apparently due to lack of precision in the geoid model bundled with the chipset) that result in bad N and H values. This results in bad MSL altitude values being shown to users."

---

OSMand on the S20 displays the Altitude correctly.
GPSTest, using the GeoID option, works just fine and has done on a variety of devices for around 15yrs.

"Other apps have decided to bundle the geoid model, or N values, WITHIN the app APK itself. However, given that the model file is tens of MB in size, this significantly increases the size of the app APK, increases app storage space after installation, and introduces performance penalties required to read the file."

[bios4]

Sidenote: OSM asks to call it "Elevation" instead of "Altitude", as the latter usually refers to the height above ground (= flight altitude - or the 0.9 meters mentioned above by @WolfgangZ42 😉).

Source: https://wiki.openstreetmap.org/wiki/DE:Altitude

So an update of the ENG translation would be nice (the GER translation is not affected), but of course this is a minor issue.

[devemux86]

Technical details (by GPSTest developer) exist in this Android issue where the new MSL altitude was introduced in Android:

"Altitude is commonly represented two different ways: meters above mean sea level (MSL), and meters above the WGS84 ellipsoid."

"some apps (including GPSTest) parse the NMEA sentences provided by Android devices via the OnNmeaMessageListener to obtain the MSL altitude."

"this method is unreliable because chipset vendors often have errors (some apparently due to lack of precision in the geoid model bundled with the chipset) that result in bad N and H values. This results in bad MSL altitude values being shown to users."

[devemux86]

Everyone please install the GPSTest app and check both "Altitude" and "Altitude (MSL)".

Compare these altitudes with Cruiser using both Android and Google location services.

https://play.google.com/store/apps/details?id=com.android.gpstest

[devemux86]

@Leeb64 What Android versions?

[MotoUKRider]

Cruiser v5 (S20, v13): AndroidAPI : ~65m / GooglePlay: ~64m (but more stable)
GPSTest Alt: ~57.8m / Alt (MSL) : ~7.5m
According to BaseCamp (using the terrain data) and FreeMapTools, I am at 18m ASL.

The GPSTest app I have always used is a different one. But the above readings came from this app we're being asked to try.

I've always been weary of Android-based GPS devices - they seem to simply get worse/slow over time (and even more so if they are air-gapped from the WWW). I guess if you want a proper discrete GPS system you have to buy a dedicated sat-nav.

[devemux86]

S20, v13

@MotoUKRider Android 13? MSL altitude was included natively in Android 14+.

[MotoUKRider]

@devemux86 The S20 only gets security updates now - I would have to root it and install my own ROM if I wanted a newer OS.
I won't use my main phone on the bike, so have always used the one I've just replaced.

[Leeb64]

-->The Android versions:
Ullefone:10
Sony:10
Pixel7:15

[devemux86]

An alternative is to compute the altitude from the atmospheric pressure using the phone barometer.

But barometer is not a common sensor like the GPS that's usually found in all phones.

[MotoUKRider]

@devemux86 ...and there's the idea I had a while ago 🤔

I'm sure there's a way that allows everybody to enjoy a feature without causing too many programming headaches or device slowdown?!

[devemux86]

@MotoUKRider

Getting elevation from routing or hill shading data is an alternative, but involves queries to the file system.
So it's not very good when this is done continuously every second with every GPS position update.
It is more useful when there is a user request for the elevation of a location, like seen in that thread.

[devemux86]

I thought of an improvement for the MSL altitude.
It will be available in the next update.

(should work on all Android versions)

[devemux86]

Display / record altitude above mean sea level is available in:

• Cruiser 5.3.0 Beta 12 #734

It works on all Android versions.

[devemux86]

• Display / record altitude above mean sea level is available in Cruiser 5.3.0 #757

It works on all Android versions.