[maemo-users] Fwd: [maemo-users] how to determine track's length from GPX-file

[From: Nils Faerber]

Armin M. Warda schrieb:
>   Hi Andew,
Hi all!

> thanks for your Ruby-Script, this solves my problem!
> 
>   http://highearthorbit.com/projects/geolocation/gpx.rb
> 
> To process one particular file generated by Maemo-Mapper I had to add abs() to the sqrt() call, see:
> 
>   http://armin-warda.de/gpx.rb
>   http://armin-warda.de/Track-1
> 
> Btw. I removed the redundant count variable, added track segment length output, and changed it from miles to km ;-)

I do not want to start nitpicking here but that solution is rather
inaccurate. It might serve as a first rough estimation but it neglects
the fact that the earth is not a perfect sphere.
The used so called ellipsoid model in GPS is WGS84 and should be taken
into account. There is no formula for calculating the distance on such
an ellipsoid but there are several algorithms to do so - sorry I do not
have one at hand right now...

>   regards, Armin.
Cheers
  nils faerber

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