[mkgmap-dev] Multipolygon-Relation checks in mkgmap

Wed Jan 25 14:56:06 GMT 2017

Hi Gerd

Using your split of germany, 63240135.osm.pbf gives me the problem
after I converted PolygonSplitterBase and AreaClipper to the new algo

It is the outer way of relation/27312 at 48.94071,13.70245
At highest resolution, openStreetMap shows no intersection, but when I
dump the highRes points after the split complains and plot them it
shows an overlap.

Ticker

On Wed, 2017-01-25 at 14:29 +0000, Gerd Petermann wrote:
> Hi Ticker,
> 
> do you have an example for such a problem case?
> 
> Gerd
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Mittwoch, 25. Januar 2017 13:25:34
> An: mkgmap-dev at lists.mkgmap.org.uk
> Betreff: Re: [mkgmap-dev] Multipolygon-Relation checks in mkgmap
> 
> 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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> > mkgmap-dev at lists.mkgmap.org.uk
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