[mkgmap-dev] Wrong multipolygon warnings

Fri Feb 12 19:06:02 GMT 2010

WanMil escribió:
>> Compiling Spain I get several warnings similar to the one below, that
>> point to data that are correct (or it seems to me).
>>
>> |2010/02/12 09:26:39 ADVERTENCIA (MultiPolygonRelation):
>> 63240004.osm.gz: Multipolygon
>> http://www.openstreetmap.org/browse/relation/319017 contains errors.
>> 2010/02/12 09:26:39 ADVERTENCIA (MultiPolygonRelation): 63240004.osm.gz:
>> Polygon 4611686018427391078[5P : (44132028[5P]) carries role inner but
>> is not inside any outer polygon. Potentially it does not belong to this
>> multipolygon.
>>
>> |Reported way (hole in the building) lacks in the resulting map.
>> Is it a know bug?
>> Another question, why are polygons so deformed in MapSource compared to
>> Mapnik?
>>
>>     
> Carlos,
>
> the way http://www.openstreetmap.org/browse/way/44132028 overlaps the 
> outer way of multipolygon 
> http://www.openstreetmap.org/browse/relation/319017. If we look keenly 
> on the definition of the multipolygon relation 
> (http://wiki.openstreetmap.org/wiki/Relation:multipolygon) this is not 
> allowed. The current implementation of mkgmap does not support this.
>   
Way 44132028 doesn't really overlap the outer polygon. They are
separated some 25 cm, but mkgmap seems to consider them overlapping.
> But it is widely used. There is a patch 
> (http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2010q1/007086.html) which 
> is not yet committed and which fixes the problem. I think it will be 
> committed within the next days.
>   
I'll test it and give feedback
> The deformations do not look good. I think the problem is that mkgmap 
> rounds the exact OSM coordinates to lower resolution garmin coordinates.
>   
May it be also the origin of the overlapping problem in the above case?