On Thu, 2009-02-26 at 20:07 +0100, Nop wrote: > Hi! > > Jon Burgess schrieb: > > For highways, unimportant roads like unclassified and residential are > > rendered first and the motorways are drawn on top. This ensures that > > motorways are not obscured by more minor roads. > > > > In addition, the presence of a layer, tunnel or bridge tag also effects > > the z_order. This ensures objects on one layer render on top of objects > > on a lower layer. > > > > The are details which I have glossed over in the description above, you > > will have to read the source to see the exact calculations. Or ask some > > more specific questions. > > Thank you, that was pretty much the information I was looking for. In > detail, I need to know what tags I can strip during preprocessing and > what tags I need to preserve for osm2pgsql. > > Do you know whether the level tag is evaluated for the z_order?
No, level is not used at all by anything in osm2pgsql. The keys it looks at to determine z_order are: layer highway bridge tunnel railway Obviously the code works if one or more of the keys are missing from any particular way, but it will take them into account if they are present. The calculations are done in: http://trac.openstreetmap.org/browser/applications/utils/export/osm2pgsql/output-pgsql.c#L280 Jon _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
