2009/10/6 John Smith <deltafoxtrot...@gmail.com>:
> 2009/10/7 Andy Allan <gravityst...@gmail.com>:
>> On Tue, Oct 6, 2009 at 12:21 PM, John Smith <deltafoxtrot...@gmail.com>
>> wrote:
>>> I understand how this may work for buildings and other POIs and it
>>> seems like a really good solution to the problem.
>>>
>>> What I'm trying to figure out is how this would apply to things like
>>> long stretches of highways?
There are also relations for complex networks of cycleways etc, many
of which make appearance in other databases as a single record
(databases such as wikipedia)
>>
>> Ah, you might want to have a look at OpenLR - a recently proposed
>> standard for ensuring that two map providers are referring to the same
>> stretch of road whilst having separate geodatabases. Primarily aimed
>> at exchanging traffic data between satnav providers it solves the same
>> problem we're talking about here - you could refer to roads in
>> openstreetmap without needing to know their osmid, and it's robust
>> against moving things around a bit and/or splitting, merging etc. I'll
>> hold off saying it definitely is the answer since currently it works
>> in theory but I haven't yet seen it working in practise!
It gets even more complex for dual-carriage ways, especially with a
tram line separating the lanes, such as [1], etc.
I just had a brief look at the OpenLR whitepaper and it, as you
describe, ensures that two map providers are referring to the same map
object - a point or a stretch of road ("Line location" in
OpenLR-speak). The problem here is that a database such as wikipedia
is not a map provider. To (nearly) reliably match a wikipedia page to
a map object you have to reproduce part of the geometry in wikipedia
and end up reproducing the map, which I think is what using a foreign
key is trying to avoid.
I said nearly reliably because even in OSM we have objects that have
the same geometry but aren't quire the same object.
>
> The reason I ask is there is a number of major highways with wikipedia
> tags that probably go inverse, wikipedia links to OSM rather than OSM
> tagging for wikipedia, I assume that's what the wikipedia tags were
> for?
I'm afraid I don't understand what you're asking here.
Cheers
1. http://www.openstreetmap.pl/wp/?lat=52.226092&lon=21.013951&zoom=18
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