On 1 February 2010 14:21, Roy Wallace <[email protected]> wrote: > 1) use tags on nodes to describe an area > 2) use an area to describe an area > > Generally speaking, I predict 2) will be easier.
Just like ways there is a lot of meta information to describe lanes, can you change lanes, do lanes have different speed limits, sure areas could be used for this, but the down side is you still need a way to describe the legal direction of travel, so the problem still exists an area alone doesn't describe everything. > Erm no. You need to know along which direction the width is measured. A node is a point, the direction of width would be 90 degrees to the direction of travel. > You could *assume* that this is in the direction that bisects the > angle between the previous and following nodes, but 1) this is an > approximation and 2) this doesn't work if the node is connected to Even areas are approximations, go look at river banks and tell me how many points are needed for an area, infinite is the correct answer anything less is an approximation. > more than 2 other nodes. Thus... nodes are hardly the "perfect point" > to indicate width. Neither are areas, they might approximate better but they still won't indicate width perfectly and they don't indicate direction of travel so we're still at square one, that is trying to describe a road, and the sub-objects, that is lanes etc. So the question still remains, how to describe a road way more accurately with a single object. _______________________________________________ Tagging mailing list [email protected] http://lists.openstreetmap.org/listinfo/tagging
