On 23 Apr 2009, at 12:32, Teemu Koskinen wrote: > On Thu, 23 Apr 2009 22:25:36 +0300, SteveC <st...@asklater.com> wrote: > >> >> On 23 Apr 2009, at 12:17, Teemu Koskinen wrote: >> >>> On Thu, 23 Apr 2009 21:34:05 +0300, SteveC <st...@asklater.com> >>> wrote: >>> >>>> I don't see a clear explanation as to why there is ambiguity if you >>>> don't do turn restrictions at the end of ways on the wiki. There is >>>> some stuff in the talk page >>>> >>>> http://wiki.openstreetmap.org/wiki/Talk:Relation:restriction >>>> >>>> Anyone care to provide an explanation? >>>> >>>> The reason I ask is that I've come across some roads where there >>>> is a >>>> restriction every other turn in both directions... and splitting a >>>> mile long road in to 30 pieces seems nuts. As a follow up, I can >>>> guess, but what will the renderer do in that situation? I'm >>>> guessing >>>> mapnik will give up trying to put 30 names on a one mile road and >>>> won't notice they're the same name? >>> >>> >>> If both from and to ways continue after the via point and neither >>> is one-way, there's two possible ways to interpret it: the >>> restriction could apply when coming from either of the ends of the >>> from-way. This of course doesn't matter if there is similar >>> restriction coming from both directions, but that's not nearly >>> always the case. And even if there is symmetry in the real life >>> restrictions, it's not appropriate in my opinion to map those with >>> just one restriction. >> >> eh? don't you assign direction by saying 'from' and 'to' ? >> > > Yes in the sense of which of the two ways you are coming from, but > if the way is not one-way and it doesn't end at the via-node, > there's two possible directions from where you can come to the via- > node using the way.
Um... no. The restriction has handedness - left or right... and the way coming off it has an angle.. lets try some ascii B | | |----------C | | | A I am going from A to B. There is no 'right_turn' restriction on the corner that stops me turning to C. That cannot be interpreted as a restriction from B to A as it would be a left turn, not a right turn. To figure that out you just need to compute the angle it makes with your direction of travel to see if it's left or right? > > > Regards Teemu Koskinen > Best Steve _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
