[OSM-talk] Overlapping Ways - Embrace or Avoid?

Lester Caine lester at lsces.co.uk
Sun May 18 08:01:08 BST 2008


Steve Hill wrote:
> mail at s-holst.de wrote:
> 
>> 1. The area shares some nodes with the highway, creating overlapping ways.
>> 2. The area shares no nodes and was drawn as close as possible to the road.
>>
>> I couldn't find any recommendations in the wiki on which option to prefer.
> 
> I prefer sharing nodes.

But it is an area that needs to be fine tuned in the guides!
In reality at smaller scales they are never in the same place, so *IF* the 
information is available to accurately plot the real area that should be used 
in preference to 'abuts' simply dropping to the shared model when the 
information is not accurate? Adding footpath and crossing information to maps 
is another aspect where the physical width of the road becomes important and 
where - like rivers - area may become an attractive alternative!

>> Overlapping ways allow a cleaner data model and saves nodes. But editing such ways is quite a hassle. There is currently no function to split nodes so that ways can be separated again. So if the border of the area needs to be changed, the complete area has to be redrawn (at least to my knowledge).
> 
> JOSM handles overlapping objects reasonably well (using the middle-click 
> menu).  If you need to separate the ways you can add a new node to each 
> way individually and then delete the shared node - could be neater, but 
> it isn't bad.

Some means of restoring a split WILL be needed in the future. I'd even go as 
far as to say that using node elements to build ways and areas is the cause of 
an unnecessary problem and that the node data for them should be integral to 
each object. However I can see the arguments either way.

-- 
Lester Caine - G8HFL
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