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

[Andy Allan]

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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