On Sun, Mar 23, 2014 at 11:16:51AM +0100, Gerd Petermann wrote:
I don't care whether the restrictions could be changed in OSM. I just want to make sure that I translate them correctly we writing the img file.
IMO, this is on the border of "garbage in, garbage out". If there are clear semantics of the role=via ways in turn restrictions that can be easily explained to a human or a computer, sure, they can be supported. It is a matter of finding balance of effort: will the implementation effort be smaller than the effort to map it in a simpler way? It also is a matter of risk: can the more complex translation rule fail the "do what I mean" semantics that the mapper might have had in mind. In the example of the only_right_turn restriction from the parking lot driveway, we could accidentally introduce an only_straight_on restriction to the main road (prohibiting any left turns). I think that we would need some kind of regression tests for turn restrictions, or routing in general. These examples can be fixed in the map data, and I plan to do so in the next few days. What cannot be fixed in the map data are no_u_turn restrictions on dual-oneways that use role=via ways. Marko