[OSM-dev] Relation - Multipolygon = "Area"

[Ben Supnik]

Hi Jukka,

One could argue that it is up to the client doing the visualization to 
eliminate these lines as part of 'interpreting' the meaning of 
overlapping or subdivided areas.

I think it's a matter of trading off ease of client interpretation 
(which would favor more explicit structures like a primitive that tells 
the client "this is subdivided", e.g. a super-area of other areas) vs. 
leaving things implicit, which is less fragile.

(If the database _tells_ the client "these are two parts of the same 
lake" then if this info is missing, the lake will look wrong.  If the 
client has to figure it out, it doesn't matter what authors do. :-)

cheers
ben


On 4/19/11 9:15 AM, Jukka Rahkonen wrote:
> Frederik Ramm wrote:
>> Ben,
>>
>> On 04/19/11 13:29, Ben Supnik wrote:
>>>> You explain "building=yes" as meaning "is it filled?", when in reality
>>>> it is completely up to the renderer whether or not to fill an object
>>>> that is tagged to be a building.
>>>
>>> Wait, I don't think I agree with this. That is, to me, the question of
>>> whether a 'thingie' in OSM is an area thingie or a line thingie should
>>> _not_ be up to the visualization layer.
>>
>> It's a two-step thing. Of course you should be able to map the building
>> and say "this is an area". But the renderer might *still* choose not to
>> render it as an area (think e.g. of certain kinds of airspace which are
>> areas but you will usually only render the outline).
>
> I would say that it is still rendered as an area but the fill is
> transparent and only outline coloured. Which brings to my mind another
> smallish problem with big real world area features which has been splitted
> to smaller areas so that they can be handled in OSM. If you want to render
> them with fill and outline the split lines come visible on the map.
>
> -Jukka Rahkonen-
>
>>
>> Bye
>> Frederik
>>
>> PS: Not that we want to map airspace. I just found it a fitting example
>> given where you're hailing from.
>>
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>
>
>
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