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

[Thom Shannon]

so how does a tile or similar area know where it is? what its in? What 
about just returning the tags for an area that entirely surrounds the box?

Andy Allan wrote:
> The europe-asia-africa landmass is pretty big, and when someone
> (eventually) adds all the coastlines together, everything will come
> crashing down. That's a lot of nodes.
>
> Less extreme examples are plausible, such as regions, countries, large
> forests (or areas of moorland, or residential areas in metropolises)
> and so on. So I don't think downloading every area surrounding the
> bbox is a good idea.
>
> Cheers,
> Andy
>
> On Nov 7, 2007 10:44 AM, Thom Shannon <thom at glow-internet.com> wrote:
>   
>>  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:
>>
>>
>>
>>  -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> 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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