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

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