[OSM-newbies] What's the easiest method to "snap" an area boundary to adjacent ways?

[Pieren]

On Sat, Aug 28, 2010 at 5:35 AM, Samat K Jain <lists at samat.org> wrote:

>
> Best practice is to NOT have ways share nodes unless there's an actual
> intersection.
>

Not true. There is no consensus on that. Each method as pros and cons which
have been developed many times on the talk list.


>
> Why? Well, after you've created such a thing… try to select and edit it.
> Yeah,
> it's a pain. No editors make it easy (though I've found Potlatch makes the
> most easy).
>

But if you have two parallel ways not sharing nodes, it's also painful to
adjust them when the topology is adjusted (say the boundary is following the
road which was traced on bad GPS trace) because you have to select pairs of
nodes.


>
> Two alternatives:
>
> (1) Draw a parallel way, with its own nodes.
>
> This is "correct" if you want to be philosophical and think about the
> abstractions maps represent… the way representing a road is supposed to be
> the
> centerline for the road.
>

The way is the centerline plus the road as a whole. It's an abstraction. If
you don't like this, then draw a polygon. For instance, if you draw an
intersection between a footway and a highway, do you cut the footway 2
meters before the intersection and 2 meters after the intersection because
the 4 meters are on the road ? If you start micromapping, you have to do
that everywhere and consistently.


>
> (2) Create a relation, making the way a component.
>
> Regarding the philosophical viewpoint above, this makes a way part of a
> boundary, which I believe is legally true in certain situations. E.g. the
> middle of a road may actually mark two different counties/states/etc. Using
> a
> relation is probably preferred but much more work.
>

But some shared lines are very small on which case you have to split it just
to add a small piece to a relation. In such case, it's easier to share the
same nodes.


> it still makes editing
> difficult.
>
>
Editing is not difficult on JOSM if you know how to use it. But it's true
for potlatch.

Pieren
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