[OSM-talk] area_with_holes as alternative to multipolygon relation

[Igor Brejc]

Frederik Ramm wrote:
> Hi,
>
>   
>> Let's go with type=area_with_holes then, roles outer and inner as  
>> before. All members are closed ways, the "inner" ways are contained  
>> in the interior of the single "outer" way. The area_with_holes is the  
>> interior of the "outer" way minus the interiors of the "inner" ways.  
>> The properties of this area are described by the tags on the "outer"  
>> way (one might also put tags on the relation here). The orientation  
>> of the ways doesn't come in.
>>     
>
> That's precisely what I thought the "multipolygon" type would do at
> the moment (minus the fact that some don't yet have inner/outer tags
> but that's being dealt with I believe).
>
> Bye
> Frederik
>
>   
I too am a little bit confused: now the whole issue basically comes down 
to renaming the relation from "multipolygon" to "area_with_holes". But
the inital proposal had some other features, like using the inner 
polygons' tags to render the inner polygons content directly (not as 
holes) + abandoning clockwise/anticlockwise approach.

Is the renaming really necessary? I think the existing renderers already 
know how to draw multipolygons even without outer/inner specification.
> That may be what we want but a significant proportion of the existing
> data also has:
> 1) an outer ring which is not a single closed way
> 2) the same tags on all of the ways
Shouldn't this be handled just by fixing the inconsistent data?

Igor

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