Fwd: [OSM-dev] proposal to kill areas

Nigel Magnay nigel.magnay at gmail.com
Sat Jul 22 13:53:56 BST 2006


---------- Forwarded message ----------
From: Nigel Magnay <nigel.magnay at gmail.com>
Date: 22-Jul-2006 12:49
Subject: Re: [OSM-dev] proposal to kill areas
To: Immanuel Scholz <immanuel.scholz at gmx.de>


> Make a map request on an "area", where the bounding box is completely
> within the area. (as example a view into a forest)
>
> You will not get the "area" returned, because a way does not need to be
> returned in this case.
>
> In fact, this example shows nicely, that areas are NOT ways, since areas
> are planear objects while ways are not. If later, we like to add some
> request as "give me all areas this point is within" (which can be
> usefull), you don't want to get ways this way. Every feature that
> depends on the two-dimensional attribute of areas will have this
> problem.
>
> I think the "simplicism" that Steves sees in traiting ways and areas
> equally is by accident and not a fundamental one.
>

This is a problem with the API and the implementation not the
specification of areas (personally I'm agnostic as to whether you want
them to be a subtype of way or not). Exactly the same thing is true of
segments - currently, the segments returned for a given bbox includes
any segment that has at least one node inside the bounding box.
However, this is not correct, since there is the possibility that a
segment may run through a bbox, but have no nodes inside it (e.g. a
road segment starting outside-left the bbox, and ending
outside-right).

The API should be returning this segment.

Areas are no worse in this regard, though are more likely to cause
problems because segment sizes are usually small, and areas are
probably bigger (e.g area of 'outline of UK' for example).




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