[OSM-talk] OpenStreetMap routing service
benlaenen at gmail.com
Mon Sep 8 17:55:27 BST 2008
On Monday 08 September 2008, Nic Roets wrote:
> If the community is capable of agreeing on one worldwide list of
> defaults, then yes. I suggest our defaults be constructed so that we
> need to retag a minimum of roads, e.g. by looking at TIGER
> classifications. Mappers will learn this short list and will be able
> to map parts of foreign countries.
> But I think they won't, in which case we need to tag everything
> explicitly. Tagging things explicitly is how you create high quality
But then you get roads tagged like this:
Explicit tags can be a good thing, but I prefer to omit these for now if
it follows the default rules of that country.
and furthermore, you can get into trouble because country X has two
classes of mopeds, country Y has no concept of hgv or psv etc. It
doesn't make sense in 99% of the world to split up between two moped
classes, so that shouldn't be done at world-wide level.
IMHO, OSM tags should work like this: there's a defined set of base
tags, for highway types or vehicle types, but they don't need strict
definitions, only fuzzy ideas about what it means. For example that a
primary road is "more important" than a secondary road.
Then it should be up to the countries to define those tags strictly
(when to use what, how to tag them, their maxspeed and access rules and
things like that). And if the global tags aren't sufficient because a
country has some special cases, then they can extend the tags (perhaps
provide some "translation" to global tags that come close to its
definition). Or a country could discard some globally defined tags if
they just don't make sense.
My opinion is that since all traffic rules are done at the country or
state level, it only make sense to define the meaning of all OSM tags
at that country level. That may need more work in renderers and routers
and everything interpreting the data, but it just seems more logical to
> It is far more common for newbies to
> misclassify a road and then we at least still have correct tags. An
> example so fresh that mapnik still renders the mistake :
Educate newbies then before they start mapping. It's a problem that
comes up now and then that you see a new person mapping some things
that he wouldn't have done that way if he read the country page for
example or a page like
which should be updated regularly and be mandatory reading material
before anyone starts mapping IMHO. That would certainly have made me
spend less time fixing someone's unconnected junctions for example.
> "(b) it fixes the problem where someone might not be familiar enough
> with the traffic rules so he doesn't know for example that
> pedestrians aren't allowed and doesn't add that access tag"
> Mappers will still be allowed to omit tags.
> I wouldn't be able to distinguish between and A road and a B road in
> the U.K. and that's what highway=road is for. But I if I see a road
> with cyclists on it, I'll know to tag it with bicycle=yes.
Yeah, but if you just tag what you see you'd be convinced that in some
places cyclists can use the pavement for example. Seeing a lot of
people doing it doesn't mean it's allowed.
But I think we can expect mappers in a certain country to at least get
an idea of the mapping rules in that country, no? It's not that much
work and you may learn you some traffic rules as well before you start
mapping that area which can reduce some unpleasant "suprises" on your
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