[OSM-talk] Left and Right - a proposal

[Gervase Markham]

Aurelien Jacobs wrote:
>> One other problem with this is that it defines a set distance from the
>> feature to the way.
> 
> I don't see this as a problem. It's in fact an additional useful
> information that your left/right scheme just loose.

Except that there's no meaningful distance that "moorings" should be
from a canal, or that "parking restrictions" should be from a road.

>> This means that, as you zoom out, the feature icon
>> migrates onto the way itself as the way rendering "thickens".
> 
> As you zoom out, the POI aren't displayed anymore, so I doubt
> this can be a problem.

It depends what the POI is, what distance you've set the node from the
road, and so on.

>> Except that relations are heavyweight things
> 
> Heavyweight things ?? I don't get what you mean here.

A relation requires you to define a minimum of three things - two
ways/nodes to be in relationship, and a name for the relationship they
have. Therefore, however good you make the editors, there is a minimum
complexity you can't get around.

Given this, and given the fact that this problem is common, we should
try and look for a more lightweight solution. The easier it is, the more
people will use it. Typing "left:" or "right:" when adding a tag is
always going to be easier than setting up a relation.

>> And a way which forms part of a canal might have (for example):
>> right:mooring=24h
>> left:embankment
> 
> How do you specify the distance from the middle of the way ?

As Richard said, you don't. In almost all cases, it's not a meaningful
number.

> How do you render a node which has a right:highway=bus_stop tag and which
> belongs to several ways ? (at an intersection for example)
> 
>          |
>          |
>          |
> --->-----+----->--

There are not many bus stops in the middle of junctions. :-)

This is the edgiest of edge cases, but if we ever were to find this
situation coming up, where the tagging could be ambiguous, then you
could just add another node to take the tag, a very short distance down
the correct way.

          |
          |
          |
 --->-----++---->--

You can make the distance between the two nodes arbitrarily small if you
like.

Gerv