[OSM-talk] Crossing ways
david at frankieandshadow.com
Sat Aug 11 19:18:24 BST 2007
On 11/08/2007 17:49, Jon Bright wrote:
> Hi David,
> David Earl wrote:
>> Here's the typical way to do it.
> I considered this, but wasn't sure. There are two problems that I see.
> The first is, as you mention, that the turning restrictions at the
> junction can't be represented.
... yet. It will come in one form or another soon, so making really
complicated junction topology is probably overkill - you'remaking a lot
of work for yourself I suspect, which will probably need to be converted
into structure designed for this case in the not too distant future.
> The second is that, at least for some
> junctions, the resulting distance between the minor road and the
> opposite carriageway is incorrect.
The carriageways have to be somewhat notional anyway when they are clsoe
together: put them too close and you can't see it is a dual carriageway.
> In my case, the junction actually ends up more like
> \ /
> \ |
I think that would be fine if there were a physical island shaped like
that, otherwise it will be misleading on an ordinary map, and a routing
algorithm probably will have a hard time not saying "proceed for 2m and
We need a technique for modelling junctions beyond their physical
layout, and I'm sure we'll get it soon.
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