[OSM-talk] National borders in the British Islands

[Andy Allan]

On Fri, May 30, 2008 at 1:23 PM, Martijn van Oosterhout
<kleptog at gmail.com> wrote:

> Because 99% of applications don't care the slightest how the internal
> subdivisions of some random country in the world compare to those in
> england. All renderers care about is "is boundary A more or less
> important than boundary B". Numbers work perfect for this and that's
> why they're used.

Yes, for rendering decisions like X >=5. That doesn't imply it's the
best approach for storing the data. Don't tag for renderers etc.

> There is absolutely no implication that admin_level=4 is the same
> everywhere. We know it isn't but we do know it's within a country,
> because countries are admin_level=2.

So how can one admin level be globally defined, but another one isn't?
"Within a country" is a farcial statement, since this entire
conversation has shown there is no global equivalence to the meaning
of the word "country". You don't need a passport to travel from Wales
to England, nor from Belgium to Luxembourg, and the United Arab
Emirates adds a whole new level of complexity...

> maintain the megabytes of rendering rules that would
> be required to make it render

You miss the point entirely, I think. Each renderer would choose the
number of boundary types it wants to distinguish between, and would
have a rule for each. So all the different types would be coalesced
before rendering. For example, I made a style last week that took
"minor", "tertiary" and "unclassified" to be the same thing (for this
particular application) and coalesced them into one rule. And to be
honest, it's not long until I decide to do the same thing for the
million shades of green on the cycle map. And if I was to do the same
with boundaries, I'd merge all the international + constituent country
borders into one style, and lump the rest together too. When it's a
pain to write mapnik filters, I'll fiddle the DB instead, or
preprocess the planet file.

But I don't demand only two admin levels, even if that suits
everything I want from OSM.

And you won't hear me saying that there are only 10 highway types, or
all green spaces should have a common tag. It's up to the renderers to
make the decisions - the database should be as accurate as possible,
not some kind of small minded kludge where someone stood up one day
and said "there can only be 10 types of border in OSM". Or do we
accept floating point values?

Cheers,
Andy