--- On Tue, 28/7/09, Roy Wallace <waldo000...@gmail.com> wrote:
> Um...the way would also be "close proximity to the bridge",
> because it
> passes under it... I don't see how finding a "node near a
> bridge" is a
> particularly elegant solution. And by random I mean the
> particular
> node you choose would be arbitrary and in an arbitrary
> position. And
> by arbitrary I mean without specific meaning.
The solution depends on what problem you are trying to solve, if you are trying
to find attributes of a bridge or restrictions of a way, my suggestion solves
the restrictions of a way I'm not trying to solve attributes of a bridge.
> I was referring to the width of the bridge. And sure,
A physical attribute like the bridge's full width, which differs to a
restriction of maxwidth is just width=*
> maxwidth exists
> but I would say that OSM ways are stored as lines.
> Mathematically, I'm
> saying a point cannot be "under" a line, unless it is on
> it.
OSM doesn't store lines, it stores nodes, it stores ways and which nodes are
memebers of that way and it stores relations and which ways are members of that
relation.
You can easily locate any node within a certain radius of any given path (or
line) between 2 nodes and do a database lookup which will spit out any results.
This is something keep right already checks for so it's not difficult, just
processor intensive on a large scale.
If you want to be really picky about this you have to remember that even
straight "lines" aren't straight as we're talking about a curved surface of a
sphere so if it's straight on a 2 dimensional plane then it would be curved on
a spherical one and vice versa. :)
_______________________________________________
talk mailing list
talk@openstreetmap.org
http://lists.openstreetmap.org/listinfo/talk
