[talk-au] Roundabouts and routing

[Roy Wallace]

On Fri, Dec 18, 2009 at 6:12 PM, Ross Scanlon <info at 4x4falcon.com> wrote:
>
> I have not changed the current intersection in osm but here are two screen shots of the intersection in josm.
>
> http://www.4x4falcon.com/osm/junctions/intersection_messy.jpg
> http://www.4x4falcon.com/osm/junctions/intersection_simple.jpg
>
> The second shows exactly the same from a map point of view as the first and also routes correctly.
>
> It's not necessary to map all the turning lanes and is much easier to read on the screen and if printed out in paper form.
>
> If you call this intersection up in garmin, navit, gpsdrive etc when in routing mode it's a real mess and becomes unusable.

This is an interesting example. The "_messy" and "_simple" techniques,
of course, could just as well be described as "_complete" and
"_approximate", etc.

The real issue here is "what are we mapping" - and with the
intersection example, the issue seems to be whether the ways should
accurately correspond to geographic reality  (_messy), or not
(_simple).

Personally, I think they should (geographic reality is important in a
map! :P), and hence I can see the appeal of _messy.

However, Ross, if the _messy example really is "unusable", this is a
problem. Ross, what exactly do you mean by "unusable"?

Note also that any problem with _messy does not then infer that
_simple is a good approach either - it's clearly an approximation,
which is fine in the interim, but sooner or later mappers are going to
want to add more detail, and they surely should have a way to do so
without making intersections "unusable".