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Measuring altitude on a garmin device

Former Member over 13 years ago

Hi there
I'm a final year student currently doing my dissertation. My project is to create a 3D map of a real world location on the computer. For this I need to know spot heights of certain areas.
I have been told that garmin devices can give a read out of the altitude through barometric pressure.
My question is to what sort of accuracy does this read out give. Are we talking a few cms or potentially a few metres?

Any help would be appreciated.
Cheers Tom

0 Former Member over 13 years ago

A few meters errors, horizontally would satisfy most Garmin users, but the vertical errors are much greater. You can minimize them by calibrating the gps at a place of known altitude, then move to where you want to make the measurements, hoping that the atmospheric pressure did not change due to factors other than altitude.

Altitude changes have been reported even by exerting some pressure on the body of the gps, such as using a touch screen.

Now, I'm talking about consumer grade hand-held gps units. There are professional units out there, quite more expensive and less portable that can do a much better job for you, as they for surveyors...