Opened 8 years ago

Last modified 5 years ago

#3605 assigned defect

Mapnik doesn't render specific multipolygon configuration

Reported by: amdmi3@… Owned by: jburgess777@…
Priority: major Milestone:
Component: osm2pgsql Version:
Keywords: Cc: Ldp

Description

Situation: Small fenced park (leisure=park+barrier=fence+name=) being an "inner" of a multipolygon representing a larger park (leisure=park).

The problem: smaller park is not rendered by mapnik (even the fence is not rendered). If I change leisure=park to e.g. landuse=grass, both polygon and fence are rendered, however such tagging is not really correct.

I believe that's part of "compatibility" with broken multipolygons which are expected to have tags which belonging to multipolygon on both inner and outer ways. In any case, it should be fixed, as it prevents rendering properly tagged objects correctly, while masking data errors (however, I haven't seen such broken multipolygons in a first place).

Here's the problem: http://osm.org/go/0t21K6eJK--

Change History (3)

comment:1 Changed 8 years ago by Ldp

Cc: Ldp added
Owner: changed from mapnik-team@… to jburgess777@…
Status: newassigned

That seems to be correct. Multipolygons where both outer and inner ring(s) have the same tags are understood to be one and the same, and no geometry is created for the inner part.

This is due to early multipolygon understanding by many mappers. Perhaps it's time to eventually rethink this assumption and just deal with the fallout (early multipolygons).

comment:2 Changed 5 years ago by pnorman

Component: mapnikosm2pgsql

comment:3 Changed 5 years ago by AMDmi3

Note that the link in the defect description no longer demonstrates the problem - I've worked it around by creating multipolygon out of inner ring as well. But still it's really time to drop legacy and avoid the need for such workarounds - I haven't seen legacy multipolygons (with tags on outer way instead of relation) for a long time already.

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