If I auto tag images using a tracklog imported from my GPS unit, altitudes visible in Lightroom are quite inaccurate. Is this because Lightroom reads altitude data from the GPS tracklog which is inherently inaccurate? If I manually place photos on the map, then the altitudes are nearer to the correct values. I am guessing that my reasoning is correct here, but is anybody able to confirm this for me?
Which version of Lightroom are you using? Are you working on Map > Tracklog > Auto-Tag Photos command to view the data?
You might use this plugin Jeffrey Friedl's Blog » Jeffrey’s “Geoencoding Support” Plugin for Lightroom and see of that shows a different set of GPS tracklog.
Using Lightroom Classic CC 7.2 release.
Some experimentation has shown me that it is my GPS altitude data which is inaccurate and Lightroom is reading altitude data from the GPS tracklog during the autotag process rather than from the mapping data. The solution is to improve my GPS data though at the moment I don't know how. Unfortunately Lightroom can't do that for me!