I don't think you need a default layer value - layer should just be used when lines (or other elements) cross, to show which is above and which below.
It's only the relative values that count, and you might need one line to pass over one feature at one point, and under it at another. (I can't think of an example now, but I'm sure there are some...) Nick Folwell [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mark Williams Sent: 21 September 2007 08:17 To: [email protected] Subject: [Talk-GB] [Fwd: Re: Conflicting tagging of london undergoundstations] -------- Original Message -------- Subject: Re: [Talk-GB] Conflicting tagging of london undergound stations Date: Fri, 21 Sep 2007 08:13:30 +0100 From: Mark Williams <[EMAIL PROTECTED]> To: Robert (Jamie) Munro <[EMAIL PROTECTED]> References: <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> Robert (Jamie) Munro wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Alex Mauer wrote: > >> I'm assuming that the vast majority of railway=subway in the world is >> below ground, >> > > You're assuming wrong. Only 45% of the London Underground is actually > tunnels. The other 55% is above ground. I expect other cities are similar. > > >> and therefore that requiring an additional tunnel=yes tag >> on 90% or more of the subway ways, is not as good as treating the >> below-ground portions as a lower layer (whether it's -1 or -2 or -10000 >> is beside the point) >> > > It might be better to abolish rail=subway and just use rail=metro. It's > then obvious that you only put tunnel=yes when it is in a tunnel. > > Robert (Jamie) Munro > > For what it's worth, London underground is of course on many layers - to some extent, each line wants a different layer tag as they cross at varying depths. OTOH I'm not sure how relevant it is, as the layer tag is largely for rendering & how important is it to render the levels right on a map? I personally would want it right, because it's there. Both tunnel & layer have their place, I would agree with the idea of the default for rail=subway/metro being tunnel=yes, even for London at 45% correct! I think I'd default layer as -3 though as not much goes under the Tube, but covered rivers go above it & I bet they're all -1 at least. Mark _______________________________________________ Talk-GB mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk-gb _______________________________________________ Talk-GB mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk-gb
