drivers: gnss: Add geoid separation to gnss_info

[maxmclau]

Currently altitude is only provided above MSL. Adding geoid separation allows for ellipsoidal height to be determined. This is important for many applications.

Curious whether others think this should live in navigation_data or gnss_info

[bjarki-andreasen]

Do you foresee an application using both references? I would expect the altitude reference to be selected using a kconfig, so its ether MSL, or relative to ellipsoid, or some other

[maxmclau]

Do you foresee an application using both references? I would expect the altitude reference to be selected using a kconfig, so its ether MSL, or relative to ellipsoid, or some other

We're working on an aviation application where both are needed. We use geoid separation to convert between ellipsoidal heights (measured from the ellipsoid) and orthometric heights (measured from the geoid). It's used along with a DEM for distance-to-ground approximation and terrain avoidance. We still report MSL altitude though, so we need both available.

I don't love it living in navigation_data, doesn't feel important enough. Maybe gnss_info?

[bjarki-andreasen]

Do you foresee an application using both references? I would expect the altitude reference to be selected using a kconfig, so its ether MSL, or relative to ellipsoid, or some other

We're working on an aviation application where both are needed. We use geoid separation to convert between ellipsoidal heights (measured from the ellipsoid) and orthometric heights (measured from the geoid). It's used along with a DEM for distance-to-ground approximation and terrain avoidance. We still report MSL altitude though, so we need both available.

I don't love it living in navigation_data, doesn't feel important enough. Maybe gnss_info?

All for putting it in gnss_info :)

[maxmclau]

Do you foresee an application using both references? I would expect the altitude reference to be selected using a kconfig, so its ether MSL, or relative to ellipsoid, or some other

We're working on an aviation application where both are needed. We use geoid separation to convert between ellipsoidal heights (measured from the ellipsoid) and orthometric heights (measured from the geoid). It's used along with a DEM for distance-to-ground approximation and terrain avoidance. We still report MSL altitude though, so we need both available.
I don't love it living in navigation_data, doesn't feel important enough. Maybe gnss_info?

All for putting it in gnss_info :)

Agreed - just moved it to gnss_info

[tomi-font]

Looks good, other than you forgot to update the commit message (and optionally, the PR title). 🙂

[maxmclau]

Do you foresee an application using both references? I would expect the altitude reference to be selected using a kconfig, so its ether MSL, or relative to ellipsoid, or some other

We're working on an aviation application where both are needed. We use geoid separation to convert between ellipsoidal heights (measured from the ellipsoid) and orthometric heights (measured from the geoid). It's used along with a DEM for distance-to-ground approximation and terrain avoidance. We still report MSL altitude though, so we need both available.
I don't love it living in navigation_data, doesn't feel important enough. Maybe gnss_info?

All for putting it in gnss_info :)

whoops 😅 - fixed