[OSM-dev] API 0.7+: Split node concept?

Matthias Julius lists at julius-net.net
Tue Oct 12 21:41:31 BST 2010


On Tue, 12 Oct 2010 22:19:15 +0200, Frederik Ramm <frederik at remote.org>
wrote:
> Hi,
> 
> Chris Browet wrote:
>> I am wondering (I wonder a lot lately ;-)) if some have already given a

>> thought to the fact that nodes actually represent 2 different concepts 
> 
> Yes, this is something that has been discussed on and off for at least 
> two years. I know because we mentioned in the first edition of our OSM 
> book ;)
> 
> Of course the "node" element would have to be kept not only for POI 
> nodes but also for topology nodes (where two ways meet).
> 
> Having geometries in ways would be much more traditional-GIS-like and 
> would simplify many things. However your suggestion mixes in-way 
> geometry with geometry by reference to nodes; and it has to because 
> otherwise you lose topology. But this means you don't get the full 
> advantages of either.
> 
> A big potential problem I see is promoting and demoting nodes - you 
> select and tag a "point" in a way, thereby creating a node; you later 
> remove the tag from the node, thereby deleting a node. You let a road 
> and a forest boundary share geometries, thereby creating proper nodes 
> for each shared coordinate; you split them apart, deleting the nodes and

> creating two sets of points-in-ways.
> 
> I see the basic idea but it all seems a but uneven to me, even ugly to 
> implement.

Maybe less ugly would be to have nodes just contain lat and lon and
introduce new point elements that need to reference a node.

That would also make it easier to put two different objects at the same
spot (like a mail box on a lamp post) as added benefit.

Matthias



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