"Arc" would make a certain amount of sense since the design of the built environment (e.g. road construction) is basically broken down into segments of lines, arcs and spirals (i.e. the transition from straight to curved sections). But then all associated tools would have to start acting like CAD applications, not just relying on the concepts used in say the OpenGIS Simple Features Specification.
In the longer term, road engineers could (should?) just be able to load their as-built engineering drawings straight into OSM. Awesome... Brendan --Original Message Text--- From: Anthony Date: Sun, 6 Dec 2009 11:59:31 -0500 We could, however, introduce a "arc" tag. And if I was better at making proposals (and/or the OSM processes were better at accepting proposals), it would probably already be introduced. To represent an arc, you only need three points (start, end, and any third point on the arc uniquely defines a triangle which is circumscribed by exactly one circle). This could even be made backward compatible. Just split the way at the beginning and end of the arc and put "arc=yes". Renderers that don't know about arcs would use three points (or four, or five, or whatever). Renderers that do know about them would use as many as is necessary for the resolution of the image. (In the case of an arc=yes tag with more than three points
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