Matt Amos wrote: > On Fri, Oct 31, 2008 at 2:53 PM, Stefan de Konink <[EMAIL PROTECTED]> wrote: >> Matt Amos wrote: >>> quick question: if your schema used ordered relations instead of ways, >>> do you have an unordered relation type as well? >> That is a client rendering issue. The order is maintained as how it is >> inserted with an explicit idx. If mapnik/geoserver doesn't care about order >> and it is just a bunch of nodes all being campingplaces, it is just that. > > would you represent a Y-shaped road as three relations, then? one for > the left fork, one for the right stem as a way-relation, then another > to group them together?
Yes, but with role='independent'. Otherwise the idx of the subtrees would create a pyramid shape. >>>> The amount of tables is reduced, that means the amount of joins are >>>> reduced. And the indices required for database searches are now more >>>> efficient. Queries therefore get shorter, no need for a specific way >>>> renderer. >>> except when your relation doesn't relate linear features. >> What do you mean with linear features? The relation still has the ability to >> relate nodes or a relations. So I don't really see what you mean. > > when you say "no need for a specific way renderer" - there is still a > need, as (in your example) you wouldn't want to render a bunch of > camping nodes as a linear feature. you'll also want to render > buildings filled. in other words: there isn't a single, specific way > renderer anyway because tag inspection is required. For Mapserver I have created a ColumnsToPoints, ColumnsToLineString and ColumnsToPolygon. What is chosen depends on the tags used. So for example a road has a tag 'highway'. This would select it in ColumnsToLineString. On the other hand, if k=Area v=True|Yes|1 it will be selected when Polygons are required. In the first version of the RelationOSM thing I created the same thing in the relationship code, when the api 0.5 was used. If the tag way=true was present, it would be rendered as <way><nds/></way>. Stefan _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev
