[mkgmap-dev] [PATCH v1] MP: Join tags by intersection and not by union

Sun Mar 7 19:19:02 GMT 2010

In case multiple ways were joined to a polygon the polygon was tagged 
with the union set of tags of all joined ways. This algorithm is not 
compatible to the tag join algorithm described on the multipolygon 
relation definition 
(http://wiki.openstreetmap.org/wiki/Relation:multipolygon#Tagging).

Additionally it can produce weired results. Example:

MP, Tags: type=multipolygon (no more)
Way 1, role=outer, Tags: boundary=administrative, highway=primary
Way 2, role=outer, Tags: boundary=administrative

The resulting polygon was tagged with
boundary=administrative, highway=primary

So a primary road was created around the complete region.

The new algorithm creates a polygon with boundary=administrative only.

WanMil
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