[Openstreetmap] viaducts

Lars Aronsson lars at aronsson.se
Wed Dec 21 03:29:21 GMT 2005

Alex Vieira wrote:

> http://www.openstreetmap.org/edit.html?lat=52.059009695368&lon=4.36880027481075&zoom=14
> The straight road does not connect to the other one, they pass 
> at different levels. Probably this question has been asked (and 
> answered) already before, sorry for that...

Wow!  I've never seen a 4-level viaduct.  I think there are only a 
handful of 3-level crossings in all of Sweden, one of them at 
Helsingborg is partially mapped in Open Street Map,

The Open Street Map project is still in an early phase and the 
data model is very primitive, really only consisting of nodes 
(points) and line segments in 2-dimensional space.  There is an 
ongoing discussion on how to make this more advanced, but I 
personally think we need a lot more data before this makes any 
sense.  My own philosophy is that OSM is just a big prototype 
where we get all the experience for the next, real system.  And 
the same goes for the World Wide Web, Wikipedia, and Linux...

When I have a 1-level crossing, I put a node (a point) at the 
center and draw all line segments to that point, for a total of 
five points and four line segments:


When I have a 2-level crossing, I don't put the point at the 
crossing, only four points at the periphery and two crossing line 
segments without connection.

  Lars Aronsson (lars at aronsson.se)
  Aronsson Datateknik - http://aronsson.se

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