On Tuesday, 17 February 2009 10:36:16 +0000, Andy Allan <[email protected]> writes: > On Mon, Feb 16, 2009 at 7:11 PM, Norbert Hoffmann > <[email protected]> wrote: > > Andy Allan wrote: > > > >>And every time using :left and :right comes up, we all have a big > >>discussion about it and then nobody pays any attention and it comes up > >>again a few months later. > > > > Perhaps this is because the concept "left"<>"right" is so simple - and the > > aversion against editors, that are not totally key-ignorant is not so easy > > to understand. > > And nobody pays attention. The main problem is that two-way roads have > no inherent, real-world, "direction" - neither side of the road is the > right or the left. Or rather, both sides of the road are the right or > the left, depending on which way you are facing.
Ok, if this is true, what is _your_ solution for the problem of placing something on the "left" or "right" side of a road ... or a direction-dependent tagging of a way attribute (e.g. oneway for a set of vehicles, different speed limits for both directions etc.)? Roads or ways have no ``inherent, real-world, "direction"'', but they have a direction within the OSM model. A way is represented by an ordered set of nodes, thus the way has something which is called "digitization direction". If I want to tag attributes/properties which are true only relative to this "digitization direction", I will use a _simple_ means to specify this ... and after reading all the current and past discussions about "left"/"right" or "in direction"/ "against direction" IMHO a direction relative tag _is_ a "simple" and "normal" concept. > The only place that > right and left has any intrinsic sense is on one-way roads, which *do* > have an inherent direction (and signs to that effect). One-way roads do _not_ have an inherent direction. I am usually allowed and I can walk _against_ a one-way road. And I know a lot of one-way roads where I can cycle against the direction, or where busses are allowed to drive against the direction. This property is vehicle-dependent. Additionally the current special handling of "oneway" and its special cases (oneway=-1 for a oneway against the digitization direction!) shows that there is a need for a concept for direction-dependent tags. Why not use the inherent digitization direction, define and document a simple tagging concept for direction dependent tags, and add support for it to all editors and tools as it is already done for the oneway tag? [...] > > Now the problem is that most people at the moment in OpenStreetMap are > tech-heads, and are so used to mental constructs and abstractions like > every road having a completely arbitrary intrinsic direction - but > that doesn't mean it's a great idea. It is not the best idea. On the other hand I have seen no other idea which is simpler to understand. > Editor support is less important > - and far easier to fix - than explaining to all the people who don't > even realise that all roads have a direction in openstreetmap - and > except for oneway roads, I have no idea which ways are pointing in > which directions, and it shouldn't be important unless it *has* to be > important. If I want to add a direction- or side-dependent tag/object to the map, the editors have to show the current (digitization) direction of the road. To edit a map we use a lot of mental constructs and abstractions of the real world (a real world road is not a line with a few pixel width, a real world intersection consists not only of two lines connected by a simple node etc.). -bernd _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
