[OSM-talk] Fwd: Nav4All navigation shut down by Navteq

[Richard Fairhurst]

Roy Wallace wrote:
> Richard Fairhurst wrote:
>> I will confess to being very disappointed that JOSM has now adopted 
>> the retarded why-use-one-tag-when-eighty-three-will-do cycleway 
>> scheme.
> So you seriously think highway=cycleway is all that's needed 
> to describe the various flavours of cycleways worldwide? If so,
> I'd be personally interested to hear your definition of a 
> "cycleway".

No, of course I don't. 

OSM tagging has traditionally worked by identifying fairly significant
"objects". This is a chemist, this is a trunk road, this is a canal. This is
a farm, this is a railway station, this is a cycleway. 

Each object contains a fair amount of meaning. This is a railway station, so
it's open to passengers, trains call here, you can wait at it until your
train turns up. This is a chemist, so it's a type of shop, you can buy
medical goods at it.

The mapper can, of course, add extra tags to make the definition more
precise. So, with the chemist, you might add opening hours if it's an
all-night chemist. With the railway station, you might add an
'access=private' tag if it's, say, a military railway station (we have one
of those near Bicester, UK) or a private one (we have one in Scotland called
simply 'IBM' :) ). And so on. In true OSM fashion, this is often iterative.
You add the basic tag first, then you go back later and refine it.

This approach is because, since mappers are our most valuable resource, we
optimise for ease of growing the map. The data consumer is expected to
postprocess, which of course they'll be doing anyway (rendering, generating
routing database, extracting and reformatting as a gazetteer, whatever). But
they only need to do the postprocessing they want. A renderer may choose not
to care that some chemists are 24 hours, and will show them all with the
same icon. A train simulator certainly won't care about that and may well
not care about the private stations - hey, the driver still stops there. And
so on.

Essentially, you tag according to the "duck test" - if it quacks like a
duck, looks like a duck, and walks like a duck, it's a duck
(http://en.wikipedia.org/wiki/Duck_test). This saves you all the work of
describing the species every time. If actually it's a rare Outer Hebridean
Florglenood which isn't quite a duck though looks and behaves identically,
hell, you just do wildfowl=duck, species=florglenood.

'highway=cycleway' is just like this. It's a meaningful object. It means a
path with physical characteristics that can accommodate a bike, where bikes
and pedestrians are permitted, and motor traffic is banned. It means,
basically, that it quacks like a cycleway. This saves a whole bunch of
tagging work, and means that clients don't need to care about the details if
they don't want to. But again, if you want to refine it, you can. You can
have 'highway=cycleway; foot=no' if that's the case.

The 'path=' tag turns OSM tagging on its head. It's a largely meaningless
object. It shifts the burden onto the mapper, who has to start with four
tags where one was enough. It makes it more difficult for, say, a renderer
which now has to parse these four tags, rather than one, to know how to draw
it. This isn't how we talk about ducks, it isn't how we tag railway
stations, chemists, trunk roads or farms, and it shouldn't be how we tag
cycleways.

> What's with the "wiki-fiddler" hatred? (not just you, Richard, in
> general) All those people advocating for a consistent/enforced/
> limited tagging scheme - how do you think such a scheme should 
> be produced? "Wiki-fiddlers" (meaning those who use and edit 
> the wiki) are the primary people who are aiming to document 
> the meanings of tags and develop a more consistent tagging 
> scheme...If you've got a problem with the definition of 
> highway=cycleway, why not stop complaining about "wiki-
> fiddlers" and contribute!:
> http://wiki.openstreetmap.org/wiki/Consolidation_footway_cycleway_path

May I refer the honourable gentleman to my answer of one year and three days
ago:
http://lists.openstreetmap.org/pipermail/talk/2009-January/033638.html

(The tl;dr version: there are much better ways of crowdsourcing tag
definitions than a MediaWiki install with no relation to the map database.)

Harry's talk from last year's SOTM ("community smoothness") is also worth
watching.

cheers
Richard
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