[Tilesathome] Splines

[Andre Hinrichs]

Am Mittwoch, den 01.07.2009, 15:18 +0200 schrieb Chris-Hein Lunkhusen:
> Hi,
> 
> Is there a way to turn of the splining (automatic rounding
> of curves) in osmarender?

I don't know of any OSM tag to do so. For local rendering you can add
rules to Osmarender which use the pseudo-class no-bezier (see
http://wiki.openstreetmap.org/wiki/Osmarender/Tips). On
http://wiki.openstreetmap.org/wiki/Osmarender/BezierCurves you can find
a description of known problems with bezier curves.

> <http://www.informationfreeway.org/?lat=51.7925353&lon=7.395977&zoom=16>
> 
> Mapnik: OK, canal in the middle of nature-reserve-area
> Osmarender: out of the middle

A way of solving such problems would be to introduce a new osmarender
special tag (e.g. osmarender:bezier=yes/no) which has also already been
mentioned on the wiki page. This has to be discussed since this would
cause many changes to the rules.

Another problem with bezier curves is with lines with far-off nodes
where the difference of the linear projection and the curved projection
can be very big (see
http://www.informationfreeway.org/?lat=60.87&lon=77.04&zoom=12&layers=B0000F000F where the difference is approx. 650 meters). Currently the only way of solving this is to add more nodes but I dream of a possibility to define that the curvature starts/ends near the nodes.

Anyway, I think that bezier curvature should by default be off for
borders.


Regards
Andre

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