[ gpsdrive ] libgps

[Jan-Benedict Glaw]

On Wed, 2008-12-24 17:43:02 +0100, Guenther Meyer <d.s.e at sordidmusic.com> wrote:
> Am Mittwoch 24 Dezember 2008 schrieb Jan-Benedict Glaw:
> > > Heading: %.2f\n  Time: %s\n", data->fix.track,utctime);
> >
> > This is track direction, not heading.
> >
> and this is not the same?

Not neccessarily. For a /car/, this is usually the same, because it
uses a static reference system (earth) for itself. However, the same
is not true for eg. planes or ships, because wind / water will move,
too.

Consider a river, flowing from north to south. Think of yourself
sitting in a very small boat, strictly /heading/ into west direction.
Your /track/ however is in south-west direction, because the flowing
water forces you southwards.

With some GPS receivers reporting track (from GPS) as well as heading
(from eg. a fluxgate compass), you can even have a changing heading
while staying at the very same position within your track.

So this is a wording issue. "Heading" is where you would go without
other forces, "track" is where you actually move to (due to outer
powers applied to you, usually outside of your control).

MfG, JBG

-- 
      Jan-Benedict Glaw      jbglaw at lug-owl.de              +49-172-7608481
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