[OSM-talk] NMEA altitude versa barometric altitude

[Nick Hill]

Hello Stephan

Nick Whitelegg has a project called freemap. It is based on the data 
collected via openstreetmap and generates a map with contour lines based 
on on freely-available NASA SRTM contour data.

http://nick.dev.openstreetmap.org/openlayers/about.php

As far as I know, almost all GPS units register elevation as well as 
latitude/longitude and time. But as Andy Robinson says, the elevation 
data is generally wildly inaccurate. (I have seen GPS elevations around 
my house vary between 70ft and 500ft averaging at 120ft, the actual 
variation in the area is around 12ft) and the old OS maps put the 
elevation at 200ft. So typical Garmin Geko elevation accuracy is around 
+/-300ft - useless for most purposes. (However, I find the Lat/Lon 
accuracy pretty good).

Stephan Schildberg wrote:

> I hope for altitude metrics will be a solution in the near future.
> 
> Stephan.
>