[OSM-talk] non-linear ways

[Simon Hewison]

Thomas Walraet wrote:
> Simon Hewison a écrit :
>> I've started writing a sanity checking script that will locate ways 
>> with  non-linear segments, yet look like a straight line.
> 
> I have mapped roundabout with 2 concentric roads linked by multiple 
> segments. How do you tag this if a normal way has to be linear ?
> http://www.openstreetmap.org/edit.html?lat=48.84853783982394&lon=2.3967192173004155&zoom=15 

Oh. wow. Parisian roads. It takes a brave motorist to drive there, 
especially if you are used to lane markings.

> I think your script is going to detect a lot of non-linear things that 
> are not mistakes...

That's so VERY non-linear. The script would avoid that entire way it 
because there are nodes that are referenced more than once in the way. 
The script is designed merely to properly align a simple way consisting 
of a set of nodes connected by a set of segments, with each node being 
used only once.

When a node is both at the start and end of the way, I call that a 
simple large roundabout, and we can cope with that as well. Some 
roundabouts get rather complicated, as they are comprised of a set of 
mini-roundabouts, and the junction as a whole can be driven either 
clockwise, or anti-clockwise.

http://en.wikipedia.org/wiki/Magic_roundabout

>> class=footpath
>> class=walking path
>> highway=footpath
>>
>> all become
>> highway=footway
> 
> I don't understand why everyone wants to use "highway" instead of 
> "class". For me (but my English is not very good), an highway is a big 
> road... It's strange to read something as "highway=footpath".

I'm sure there was a reason for it. "Blackadder" was the first to 
propose it, and it seems to have taken of. Your English is much better 
than my French.

> But I strongly agree we should try to all use the same key/value for the 
> same things. If the standard is "highway", the applet should be 
> modified. It currently drive the user to use "class".

Most of the uses I've seen of the labels can cope with both. I was 
suggesting this as an attempt to standardize.

I think the applet is driven by a server-side configuration file for this.

-- 
Simon Hewison