[glideplan_swproj] Re: Line drawing
- From: Kuba Marek <blue.cube@xxxxxxxxx>
- To: glideplan_swproj@xxxxxxxxxxxxx
- Date: Tue, 24 Apr 2012 19:35:56 +0200
Look here:
https://secure.wikimedia.org/wikipedia/en/wiki/Great_circle_distance#Radius_for_spherical_Earth
It should be within 1% (?) for the quadratic mean radius that Ales is
using. There seems to be another way of calculating it, that works on
ellipsoidal earth
( https://secure.wikimedia.org/wikipedia/en/wiki/Vincenty%27s_formulae
), but looks a bit too complicated to me.
Harder question now:
The great circle distance should be available to all parts of updraft.
Where to put it? Utils::Location?
K
> Hi
>
> yes it's an approximation that should be sufficient in most of the
> cases (imho).
>
> A.
>
> 2012/4/24 Tomáš Zámečník <pulcik@xxxxxxxx>
>
> > This is not distance on ellipsoid WGS84, but on some sphere with r =
> > EARTH_RADIUS_IN_METERS.
> > T.
> >
> > > ------------ Původní zpráva ------------
> > > Od: Ales Zita <ala.zita@xxxxxxxxx>
> > > Předmět: [glideplan_swproj] Re: Line drawing
> > > Datum: 24.4.2012 09:56:34
> > > ----------------------------------------
> > > Hi
> > >
> > > I use the following distance calculation in airspaces:
> > > have a look at
> > >
> > https://github.com/updraft/updraft/blob/master/Updraft/src/plugins/airspaces/oaengine.cpp
> > > row 509 :
> > > double oaEngine::DistanceInMeters()
> > >
> > > A.
> > >
> > >
> > > 2012/4/24 Tomáš Zámečník <pulcik@xxxxxxxx>
> > >
> > > > I don't know how to compute distance on WGS84, maybe there are
> > > > some routines in osg/osgEarth.
> > > > Have you any idea?
> > > > Maybe it would be sufficient to subdivide the line with
> > > > osgEarth::Symbology::MeshSubdivider to some level (subdivision
> > > > step is defined with radians) and somehow take the data from it.
> > > >
> > > > T.
> > > >
> > > > > ------------ Původní zpráva ------------
> > > > > Od: Kuba Marek <blue.cube@xxxxxxxxx>
> > > > > Předmět: [glideplan_swproj] Re: Line drawing
> > > > > Datum: 24.4.2012 00:36:21
> > > > > ----------------------------------------
> > > > > Is there any realistic chance someone is going to use tasks
> > > > > this
> > large?
> > > > > Because if there is, then I need to fix calculations of task
> > > > > distance (now it uses euclidean distance in XYZ, it would
> > > > > probably be better
> > to
> > > > > use great circle distance)
> > > > >
> > > > > K
> > > > >
> > > > > > I found an easy way how to draw lines on the earth surface.
> > > > > > It can be done with osgEarth::Symbology::MeshSubdivider,
> > > > > > which subdivides (any?) geometry according to ellipsoid
> > > > > > surface. It's
> > very
> > > > > > easy to use - just call one method on your geometry and
> > > > > > specify wheter you want to interpolate according to great
> > > > > > circle or not.
> > ...I
> > > > > > send screenshot (in attachment) of declaration of 25000km
> > > > > > FAI triangle :-)
> > > > > >
> > > > > > T.
> > > > >
> > > > >
> > > > >
> > > >
> > > > To visit archive or unsubscribe, follow:
> > > > //www.freelists.org/list/glideplan_swproj
> > > >
> > >
> > >
> > >
> >
> > To visit archive or unsubscribe, follow:
> > //www.freelists.org/list/glideplan_swproj
> >
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