[mkgmap-dev] Multipolygon-Relation checks in mkgmap

Wed Jan 25 12:25:34 GMT 2017

Hi Gerd

Yes - please

I started looking at MultiPolygonRelation yesterday with a view of
trying to convert it to use the new ShapeSplitter algorithm.

I think that the way a self-intersecting polygon is rewritten after a
split using the Java2D library causes problems for the new algorithm
when it makes a later cut for points limits or subdivisions, even when
the next cut isn't in the overlapped area. 

All I've done so far is convert a few more places to use highPrec logic
and then slightly disparaging at the complexity of the whole thing.

Ticker

On Wed, 2017-01-25 at 09:05 +0000, Gerd Petermann wrote:
> Hi all,
> 
> I'd like to rewrite the code in MultiPolygonRelation so that it
> tolerates more mp-rels.
> For example, the relation  
> http://www.openstreetmap.org/relation/2199651
> produces these warnings:
> WARN: uk.me.parabola.mkgmap.reader.osm.MultiPolygonRelation 
>  f:\osm\rel2199651.osm: Some polygons are intersecting. This is not
> allowed in multipolygons.
> WARN: uk.me.parabola.mkgmap.reader.osm.MultiPolygonRelation 
>  f:\osm\rel2199651.osm: - http://www.openstreetmap.org/way/165084794
> WARN: uk.me.parabola.mkgmap.reader.osm.MultiPolygonRelation 
>  f:\osm\rel2199651.osm: - http://www.openstreetmap.org/way/165084810
> WARN: uk.me.parabola.mkgmap.reader.osm.MultiPolygonRelation 
>  f:\osm\rel2199651.osm: Polygon
> 4611686018427387906(8P)(165084810[8P]) carries role inner but is not
> inside any other polygon. Potentially it does not belong to this
> multipolygon.
> The inner way touches the outer way in one point. My understanding is
> that this is correct, mkgmap should not complain about it.
> 
>  OK?
> Gerd
> 
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