[GRASS-dev] latlong problem

[Martin Landa]

Hi Glynn,

2007/3/7, Glynn Clements <glynn at gclements.plus.com>:

> > there is a significant problem in LatLong location. Try the following:
> >
> > g.region n=80 s=-80 w=-170 e=170 res=1;
> > v.in.region out=reg;
> > g.region n=90 s=-90 w=-180 e=180 res=1;
> > d.erase;d.vect reg
> > [1] should be [2]
>
> No, [1] is correct.
>
> Given two points at the same latitude, each 10 degrees either side of
> the 180th meridian, the line segment between them is deemed to be the
> one which subtends 20 degrees and crosses the 180th meridian, not the
> one which subtends 340 degrees and crosses the prime meridian.
>
> IOW, "shorter" has a higher priority than "doesn't cross the 180th
> meridian".

OK, then I understand. Anyway, the centroid should be placed inside
the area. It is at least confusing.

So the problem with "buggy" maps which Markus described still remains.

Thanks for explanation.

Martin

-- 
Martin Landa <landa.martin at gmail.com> * http://gama.fsv.cvut.cz/~landa *