Re: altitude measurement

hello johann.

> Is it possible to explain when and why are altitude expressed in feet 
> and when and why are meters utilised.
> I know that in aviation and in mapping  feet are still used and in 
> construction meters, why the difference?
> What is the correct or rather preferred unit to be utilised.

your preferred depends on your application and/or end user. unit 
conversions are trivial as long as any measurement has a unit attached 
to it. the discussions on the list were not about units, but the fact 
that there are various methods of how to *measure* altitude (barometric 
vs. GPS) and to *express* altitude (WGS vs. EGM), regardless of how the 
value is then represented in some unit. the issues i raised were related 
to the question if and how various measurements/references should be 
exposed (if a device is capable of making them). the majority voted for 
the device magically coming up with "the altitude" (whatever algorithm 
the device uses to combine potentially conflicting measurements), and 
this one value will then be exposed through the API.

cheers,

erik wilde   tel:+1-510-6432253 - fax:+1-510-6425814
        dret@berkeley.edu  -  http://dret.net/netdret
        UC Berkeley - School of Information (ISchool)

Received on Tuesday, 5 May 2009 17:08:31 UTC