That is a really good and interesting point, Chris. I just confirmed that iD leaves the north / south / east / west roles alone when reversing a way. Neither does Potlatch (although Potlatch does not seem to actually allow you to reverse a way, just to flip the oneway= between 1 and -1). At least iD would need to be patched for this, I would say. I submitted one: https://github.com/systemed/iD/pull/2004
On Thu, Nov 21, 2013 at 1:27 AM, Chris Lawrence <[email protected]> wrote: > On Wed, Nov 20, 2013 at 2:32 PM, Martijn van Exel <[email protected]> > wrote: >> >> Reading through this I see that most are in favor of avoiding dividing >> relations more than necessary: no separate relations for directions, >> especially not if the geometry is the same for both. >> >> That leaves the question of how to tag cardinal directions? As I said >> before, I think the role tag is suitable for this. It's already used >> pretty widely (with around 100k ways having a cardinal direction as >> the role tag in a relation), documented >> (https://wiki.openstreetmap.org/wiki/Route#Members) and it replaces >> the forward / backward role values that are not particularly useful or >> meaningful. >> I created a stub of a wiki page that we could use to describe the >> preferred tagging in more detail: >> >> http://wiki.openstreetmap.org/wiki/Highway_Directions_In_The_United_States. >> (The current content is geared towards using the member role tag, but >> this can be changed depending on the outcome of this discussion.) > > > The only problem I can anticipate with this tagging scheme is that it's > possible some editors don't understand anything other than > left/right/forward/backward (I think), we could end up in data loss > situations fairly easily. > > For example: way X pointing east is marked in relation Y as "east" > (presumably we could assume that "east" = forward and the opposite cardinal > direction "west" is backward). User reverses way X. Now the relation role is > potentially backward. JOSM seems to understand at least north/south and > east/west and offers to fix it (see > http://josm.openstreetmap.de/browser/josm/trunk/src/org/openstreetmap/josm/corrector/ReverseWayTagCorrector.java); > no idea if iD or Potlatch do. > > We'd also need to make the validation tools smarter to recognize lossage > (for example, realizing that the route is unbroken only if the chain of role > tags once you account for the directions of the underlying ways is > monotonic), > > > Chris > -- > Chris Lawrence <[email protected]> > > Website: http://www.cnlawrence.com/ > > _______________________________________________ > Talk-us mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/talk-us > -- -- Martijn van Exel OSM data specialist Telenav http://www.osm.org/user/mvexel http://wiki.openstreetmap.org/wiki/User:Mvexel http://hdyc.neis-one.org/?mvexel _______________________________________________ Talk-us mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-us
