[OSM-talk] Topology

Frederik Ramm frederik at remote.org
Thu Apr 26 18:40:17 BST 2007


> Well, some nodes which might appear to be uninteresting (ie they simply
> define the geometry of the way) actually carry interesting tags. However,
> I've no idea whether the tag data on an object affects this discussion or
> not :-)

This is a problem we touched on in the paper as well.

I agree with Artem that it would be desirable to make a distinction 
between points that are really needed "as objects" - because they denote 
an intersection, the beginning of a speed limit, or a phone booth - and 
points that are just there to define a shape.

Points "as objects" can enter into relationships with other objects; 
"shape points" cannot.

Since there is no distinction between the two at the moment (i.e. what 
you say, uninteresting-appearing points suddenly have meaning), it is 
easy to break things (e.g. I want to change the shape of a stretch of 
railway and accidentally move or delete a railway station). This could 
of course be fixed at editor level (simply give a different colour to 
nodes that have tags, assuming that having tags is what makes them 

So, one could say that making the distinction in the database or data 
model is just a case of premature optimisation. I'm not sure, maybe it 
is, but currently I like the idea of explicitly defining: This is a 
point with a meaning (even if I don't give it meaning right now), and 
this is "just a point".


Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'

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