On Fri, 12 Dec 2008 09:10:32 +1100 Ian Sergeant <[email protected]> wrote:
> As is everyone - but we can't forget that a linear road is always > going to be a representation of a 2 dimension road surface, and > currently that is what we have to work with in OSM. If you were > drawing the full road width in OSM, the road wouldn't actually > deviate at all for a mini-roundabout, it would just be drawn within > the width of the road. Mapping a 4-node deviation in the road for a > mini-roundabout isn't actually what is on the ground, either. The >question remains, how to best represent what is on the ground. But this interpretation is entirely dependant upon the width of the road, an older 5-6-car-wide inner suburban road can eat up a 4 car wide roundabout and make it 'mini' whilst a new suburb where they build roads only slightly wider than 2 cars it's have a smaller 2-3 car wide roundabout where the full structure of the road differentiates radically. Following your reasoning we would have the latter case represented at something closely approaching reality and the former case rendered as if the road junction is a big slab of asphalt. In addition, if we follow this reasoning we might as well throw out the bridge as a way concept for around 50% of all bridges, most of them a small foot track across a creek and similar, but also including largish bridges such as the South Road/Port River Expressway bridges in Adelaide. The bridges are only as wide as the lanes going over them and there are walls built up on either side right next to the lower roadway, so there's no bridge that extends outside of both roadway more than centimetres. So to map what's on the ground by this stance it should be a point. > > I plan on submitting a proposal for the roundabout tag, where you > > can add it to a node like a mini_roundabout, for use in simple > > suburban type roundabouts. Something like junction: > > inner_width=3mcould specify the island size, making it possible for > > pretty rendering. Weird intersecting ways or large roundabouts would > > have to continue as is. > > Oddly enough, these seems almost completely contrary to what Darrin is > arguing, and aligns well with that I would like to see happen. I > really don't care whether the tag is called mini_roundabout or > something else, I think the junction is best represented by a single > node. Darrin believes that it is better represented by have a loop. If I was to accept that your above point was valid (obviously I don't), then I would agree with BlueMM, because I believe there is a fundamental difference between the mini and a real roundabout (the presence of the centre Island, even if it's not marked on the map). I thank you Ian that you seem to have summed up my position better than I have, and that this discussion has clarified for me that the issue is very much tied to the presence of the island. -- =b _______________________________________________ Talk-au mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-au
