[OSM-talk-be] some thoughts and remarks about border mapping

[Ben Laenen]

On Wednesday 24 September 2008, ivom wrote:
> On Tue, 23 Sep 2008, Ben Laenen wrote:
> > btw, the relation way may need one extra thing: a "left" or "right"
> > role for the members telling on which side the entity is. I think
> > it's needed for solving ambiguity, especially with ex- and
> > enclaves.
>
> I am not sure I understand your tagging proposal correctly, but by
> posing an example you might be able to make this clearer.

It's quite easy. If you have a way like this:

      place X
a -----------------------> b
           place Y

and your relation encloses place Y, then the role of a-->b  would be 
rigth because place Y is on the right of a-->b.

Likewise, the role would be left for the place Y relation.

But I haven't thought about it thoroughly yet if it's really needed. But 
the fact that OSM needs things like multipolygon relations makes me 
think they are needed when there are holes in it (i.e. enclaves or 
exclaves).

> I live near a street called the Bacchuslaan. On one side of the
> street it's Borgerhout and on the other it is Berchem. The border
> runs through the street and does not cross it. So,

I wasn't talking about adding the roads itself to the boundary 
relations. I still want the boundaries as separate ways. In this case 
that boundary way would overlap the Bacchuslaan (and probably make use 
of the same nodes).

I don't know if adding roads or waterways to the boundary relation would 
be a Good Thing™

> * I would add this way to 2 relations.

Now I have ideas on how to solve the problem of left and right side of 
the road belonging to different municipalities or districts, but I need 
to work it out first :-)

Ben