Hi!
I’m just wondering why the ele-Key is used so rarely. Most (if not all) gps trackers are able to capture the current height above sea level. So why not using this information for every street node? I think it would really help people who work on 3D visualisation. The wiki says, the ele-Key “is mainly intended for mountain peaks but could also be used for elevation of airport runways and many other objects”. Is there a special reason for not capturing the elevation of streets?
Elevation is the least accurate value given by a typical handheld GPS unit. At least it is on the three units I have. I think you’d need to average quite a few readings to get a believable elevation. If you want to do 3D visualizations, there are Digital Elevation Model (DEM) datasets available for most of the world without cost or copyright issues. Most are based on the SRTM data collected by the U.S. Basically it provides a grid of elevation values for an area. One could use that as a base layer to add the OSM data to for 3D display.
This is what is commonly being done today. Unfortunately, the openly available DEM are too coarse for street-level 3D visualization, so it would be preferable to get better data.
You are correct, though, that consumer GPS units don’t offer sufficient vertical accuracy. It’s not an easy problem to solve.