[OSM-talk] Left and Right?

[Dave Stubbs]

On Wed, Aug 27, 2008 at 12:13 AM, Robin Paulson <robin.paulson at gmail.com> wrote:
> 2008/8/26 Mark Williams <mark.666 at blueyonder.co.uk>:
>> Is 'mapping for renderers' any worse than 'mapping for routers'?
>
> both are bad i think
>
>> Step back from the "we're going to use it for routing busses" approach a
>>  moment; a fair few users may wish to print a map, so the renderers need
>> to do this right. I will prefer to see the bus-stops pass on the sat-nav
>> map as reference as I drive by them. I might like warning of busses
>> likelihood of stopping.
>>
>> My main driver on this is that they are roadside features, not highway
>> features. As I said, like pubs, postoffices, etc. This is the real
>> world, mapping what's on the ground, bus stops are not like
>> mini-roundabouts or traffic lights.
>
> well, it's a representation of the real world, and idealised, yet
> imperfect one at that
>
> i'm not sure why they're roadside features, rather than highway
> features. the bus stops *on* the highway (which includes the path, as
> we discussed earlier). at no point does it leave the highway
>
> the *sign* is on the roadside. we're not mapping signs. maps and signs
> do the same thing, but in different ways - they contain information
> about a mapworthy feature, but each are not mapworthy themselves.
> we're not mapping signs


What it comes down to is this: a bus stop is not the same thing as
where the bus stops. Although they're obviously related. We have half
the people in this discussion trying to map the bus stop, and half of
them trying to map where the bus stops, and half happy to do either
really... so yes, it has a sign (and possibly a shelter), but it's not
_just_ a sign: it's a destination in its own right and about the only
sign I can think of right now that people queue up behind. It's also
very important where it is, unlike most signs which are just telling
you something about somewhere else.

Whether a "bus stop" is a feature of the road, or a feature of the
pavement is entirely a matter of perspective...

If I happen to be standing at a bus stop I really don't care which
road the bus will come down to pick me up: I'm at the bus stop so it
should be fairly obvious. And the only important thing is how to get
to the bus stop, because if I'm not in the right place the bus won't
stop even if I wave at it frantically (OK, this bit varies from place
to place... usually inversely proportional to the number of buses :-(
)

On the other hand if I'm on the bus, then the exact position on the
pavement of the bus stop where I get off isn't important. I just want
to know when the bus has got to the right part of the route and I
should hit the button to get off. The bus will stop in the right place
on it's own (wow, magic).

Any arguments re the pavement being part of the road anyway are
ultimately flawed... ie: post boxes phone boxes, cycle parking and
even ATMs would be way nodes under this definition.... and whether or
not they should be doesn't really matter, as I don't think anyone is
adding them as such.

We can't represent both properties properly with a single node. In
either case we lose something, or else make reconstructing it
difficult. So I'd suggest this: map both, or whichever you happen to
be interested in, and someone think up a way of binding them together
nicely with a relation for the topologists.

Personally I just stick a node where the bus stop actually is. That's
what is most useful for me at the present time.

Dave