[OSM-dev] Drawing ways with bezier curves rather than line segments

Jochen Topf jochen at remote.org
Thu Jan 25 09:27:05 GMT 2007


On Wed, Jan 24, 2007 at 10:53:59PM +0000, Barry Crabtree wrote:
> >> I've been experimenting with using bezier curves to connect the
> >> segments in a way rather than using straight line segments as it is
> >> done at the moment. There is a before and after image at
> >> http://wiki.openstreetmap.org/index.php/User:Dotbaz - this was
> >> somewhere (Kobenhavn) I caught as it was going past my tiles at home so
> >> hopefully someone has recently edited this area and might know it!
> >the 2nd picture (with the railway station Wankdorf) is Berne,
> >Switzerland and i have to say it's impressive! at first i thought
> >rounding everything would be wrong since all geo-tools work with
> >straight lines (at least without the projection) but having seen it, i
> >have to say it's much nicer to present (not to work with, but for
> >rendering/presentation) and it doesn't over-compensate as i thought it
> >would
> 
> 
> It did the first time I ran it :-) - made for a very wavey map before I made
> sure it didn't make sharp angles curvy!
> 
> - it'd be nice to see it on a very long segment which has hard,
> >short turns on both ends. somewhat like a race-track but more straight
> >in the middle.
> >________
> >(________)
> 
> 
> It should deal with that fine - if the bends are sharp it doesn't try to
> over-curve them.

Generally the curved ones look much better, but there are problems: If
you look at the Copenhagen map in the park on the top (Kongens Have).
There are some footpaths that look like an X with a square in it, somewhat
like a diamond shape. These paths look better with straight lines.

So I think if we want to use beziers we'll have to have some hints in
the data telling the renderer whether its ok to use them.

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298





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