[OSM-talk] Cycleways wiki doc enhanced

[Claus Hindsgaul]

2010/1/3 Lester Caine <lester at lsces.co.uk>

> In large areas of the world, the macro level of mapping is now 'complete',
> and
> people are adding fine detail like 'post boxes', parking bays, drive ways
> and
> the like.


That is really great, but these "large areas" still cover a small proportion
of earth. Most of the work is still pending, and in the best covered areas,
it is great to add such information and refine with tags such as maxspeed
etc. Who are these "some people" that firmly believes that such details
"should not be present at all"? If any, I expect them to be very few.

I welcome your increasingly relaxed retoric, indicating that you acknowledge
that utopia is neither total micromapping with fragmentation into separate
entities everywhere - nor exclusively macromapping (or, as I might call it,
metamapping), where several part of e.g. roads are collected as tags in
collective entities.



> If a cycleway exists as a separate area of 'highway' then it
> should be mapped as such. Adding tags to a near by road with additional
> tags for
> things such as gaps between two physically divided areas will always be
> wrong,
>

Not understood... How can it "always be wrong" to tag a bicycle track as
tags in a road located just one curb or 1 meter of grass away, and aligned
with the road? If we create a rule that it is wrong, of course yes. But this
method incorporates information to the construction that you would not have
with separate entities. Most prominently that you can move (yes on your
bike) across the curb/grass to and across the road and that they are
elements of the same street. In this view, I could with the same right say
that it is "always wrong" to implement it as separate entities...

I think the he essense is, that our map will always - with your words - be
somewhat "wrong", as we will never be able to describe every property of the
real world.

but at a macro zoom level there should be some shorthand way of combining a
> number of ways into a single 'route' element. THAT is the level of
> agreement
> that needs to be reached! The lowers levels should always map the 'bridge',
> footways, vehicle ways, and any other structures such as verges, banks,
> slopes
> and the differences between their levels, while the macro view gives a
> 'way'
> with a bridge tag. Surely that is the current target?
>

(Are we talking about the existing OSM environment, a future version or
another project??)

Yes, your described scheme might be very useful to minimize the shortcomings
of micromapping. The problem is, that it does not currently exist at all in
OSM. Until it does, the result of fragmenting a street into many different
entities (car way, cycle ways, sidewalks etc) will be: potential for
increased precision in physical traffic traces at the cost of loss and
intoxication of routing information.

-- Now back to the thread topic, bicycles :-) --
My conlusion: in the existing OSM environment, metatagging (one way with
tags for bicycle tracks, sidewalks etc.) of streets should be preferred for
fragmentation into separate micromapped entities, unless the fragmentation
is necessary to describe significant information. My first post in this
thread lists the talk-dk concensus of such exceptions for bicycle tracks.

In another environment (other project, maybe future OSM), the conclusion may
be very different. A potential future "everything is an area" approach will
not be able to take over any separate parallel bicycle ways without a new
very detailed survey anyway.

-- 
-- 
Civilingeniør ph.d. Claus Hindsgaul
Edvard Thomsens Vej 19, 5. th
DK-2300 KBH S
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk/attachments/20100103/51366d5a/attachment.html>