On Fri, 25 Jun 2010 06:10:18 +0000 (UTC), Ed Avis wrote: > John Smith <deltafoxtrot256 <at> gmail.com> writes: > > >>and uphill/downhill for slopes (based on the layer of the endpoints). > > > >Layer has nothing to do with elevation, it only indicates which road > >goes over the other road there may not be any slope involved. > > True, but if a way is tagged highway=steps or slope=yes, it's a pretty safe > bet that going from layer 0 to 1 is uphill, and 1 to 0 is downhill. Even > though in theory there is nothing to guarantee that.
Not only theory. Suppose you have a downhill highway=steps intersecting some other thing below. It's up to the mapper whether to tag this "thing" layer=-1 or to break the highway=steps and tag the middle segment layer=1. With your example, instead of the reality, you'd be ending up with an up followed by a down. layer=* is just really for the rendering, and shouldn't be used for anything else. > (And if elevation is tagged, uphill and downhill markers can be deduced for > certain.) Yes, that is the only safe tag. -- . ''`. Debian developer | http://wiki.debian.org/DavidPaleino : :' : Linuxer #334216 --|-- http://www.hanskalabs.net/ `. `'` GPG: 1392B174 ----|---- http://deb.li/dapal `- 2BAB C625 4E66 E7B8 450A C3E1 E6AA 9017 1392 B174
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