GOUPIL 30101 <[email protected]> writes:

> Hello, have you also observed altitude errors of the order of 40 to 50 
> meters in addition to the actual altitude? Did you manage to correct this? 
> Cordially. 

This is complicated:

  The android location API returns "height above ellipsoid (HAE)" which
  is not what people call altitude.

  osmand is just a client using your phone's GPS (GNSS) receiver.
  First figure out if the phone is ok.   Install GPSTest which will show
  "Height Above Ellipsoid" labeled, somewhat confusing, as "Alt", and
  "WGS84 Orthometric Height", which is very close to what people mean by
  altitude as "Alt (MSL)".  You will notice that they are different.

  To look up the difference between HAE and WGS84 Orthometric Height,
  see
    https://geographiclib.sourceforge.io/cgi-bin/GeoidEval

  osmand has a downloadable map called world altitude correction.
  Without it, osmand displays HAE, and with it, WGS84 Orthometric
  Height, which is effectively a global definition of altitude.
  Make sure you have this installed.

  You would be correct to say that this is all unfortunate.  That the
  complexity exists is unavoidable, but that you are having to deal with
  it is because of the choices made in writing the Android API.

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