|Tagging:||smooth=yes or no|
|Definition:||Signals that this map element is smooth|
Signals that a linear feature (or the boundaries of an area) are smooth in reality. Renderers would apply a predefined interpolation algorithm between the given nodes, for example the one described in this paper.
Through the use of this tags, editors can more accurately describe the appearance of smooth features with fewer nodes. Two example usages are on ways describing railroads and motorways. Both are nearly always follow a very smooth trajectory.
Key applies to anything linear. In practice this would be to ways describing roads, ways describing areas (in which case it would mean that the boundary of the area is smooth) or relationships of type multipolygon that describe areas (in which case it would mean that all the boundaries are smooth)
Rendering would follow a predefined algorithm. Ideally editors would also use this algorithm when displaying such roads. This way the editor can correctly judge the number of points needed to accurately describe reality when editing. It is important that all renderers and editors, should they implement support for this tag, use the same interpolation algorithm.
I think it would be better and better customizable to add the possibility to draw bezier curves --Bkr 14:49, 3 June 2008 (UTC)