[OSM-talk] Fetch whole relation when parts of it are in bbox

[Thom Shannon]

Perhaps a useful solution to this would be to return any area that 
entirely surrounds the bounding box?

I think I may have a SQL example of something similar somewhere

Steve Coast wrote:
> On 3 Nov 2007, at 14:33, Robert (Jamie) Munro wrote:
>
>   
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>> Jannis Achstetter wrote:
>>     
>>> Hello there,
>>>
>>> I've got a problem with one specific tile:
>>> http://www.informationfreeway.org/?lat=49.974240779456515&lon=9.44955088920595&zoom=12&layers=0B00F000
>>>
>>> You see that "inverted" tile right in the middle? This is actually  
>>> not a
>>> bug in osmarender but in the API as far as I can see. I looked at the
>>> .osm-file it gets from the server and if I were the renderer I would
>>> have drawn it pretty the same as you can see this now. The problem  
>>> is:
>>> We do have a multipolygon-relation here with the outer area (more  
>>> than
>>> 1000 nodes) and some smaller areas which are no forests. Now I ask  
>>> the
>>> API to give me the area and it does only return the smaller sub- 
>>> areas,
>>> not the outer one (meaning: only a part of the relation). So, how  
>>> do I
>>> know that these are no forests?
>>> Wouldn't it be good if the server would give me the whole relation  
>>> and
>>> not only the parts that are inside the bbox? Would this introduce any
>>> problems for osmarender or other software?
>>> Technically I think this will not be a too huge problem since the  
>>> server
>>> returns a whole way when only a part of it is inside the requested  
>>> bbox,
>>> so why can't we do the same with relations?
>>>       
>> Because relations can be big. You don't want to download the whole M1
>> motorway from London to Leeds just because you are working near Brent
>> Cross shopping centre. Also, do you then download all the relations of
>> all of the ways that you have downloaded?
>>     
>
> That was the argument for not including all segments that were part of  
> a way which crosses a bounding box (that stopped in 0.4)
>
>   
>> (personally, I think that returning all the nodes of a way even when
>> they are outside the bounding box is a bad idea unless you have  
>> actually
>> asked for them).
>>     
>
> ah..
>
> have fun,
>
> SteveC | steve at asklater.com | http://www.asklater.com/steve/
>
>
>
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>   

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