[mkgmap-dev] boundary relations in splitter

Tue Feb 12 08:08:57 GMT 2013

Hi all,

the keep-complete processing in current splitter (r283) ignores all
type=boundary rels, means,
they are not added to the problem list. This is done to avoid adding
thousends of ways 
to each tile because of administrative boundaries covering huge areas.
(Boundary rels are treated like type=multipolygon rels, so splitter will
calculate the
bounding box of the rel and add the members to all tiles intersecting this
bbox.

The discussion in this thread
http://gis.19327.n5.nabble.com/Commit-r2478-Use-outer-polygon-tags-if-the-multipolygon-is-tagged-with-name-only-tp5748386.html
shows a need for more detailed filters.

I see  some options to handle this:
1) 
a) we can add type=boundary relations if they have a boundary=xyz tag and
xyz is in a hard coded 
include list
b) we can add type=boundary relations if they DON'T have a boundary=xyz tag
and xyz is in a hard coded exclude  list
I looked at taginfo and found quite a lot of candidates for both lists:
http://taginfo.openstreetmap.org/keys/boundary?filter=relations#values

2) we can pass the include / exclude lists as parameters (eg.
--incl-boundary-filter=national-park,national-forest   or
--excl-boundary-filter=administrative,postal_code

3) we can add (parts of) the style system to splitter to allow the same
filters

My opinion:
option 1) is too simple, option 3) is too complex (for me)

On the other hand, we may also filter type=multipolygon rels , for example
taginfo shows that type=multipolygon is often used with
boundary=administrative.

Comments?

Ciao,
Gerd

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