On Mon, Nov 30, 2009 at 10:09 AM, Roy Wallace <[email protected]> wrote: > interpolation. But approximation with trapezoids or whatever is a bit > fudgy....e.g. what if you *do* want to represent an instantaneous > change in width?
I can think of several options, and I'm sure you can too :) > My point is that this general suggestion seems to be a way to *map > areas*, by *tagging ways*. Is this actually better than to *map areas* > by *tagging areas*? If so, how? I can think of a few reasons it would be better: * No parallel data structures. Ie, there is just a way, with markup, rather than a way and an area. (I don't think simplying have an area without a way is viable, as it imposes too great a burden on routing software.) * Conceptually cleaner. From the point of view of a map, a road really is a line...that happens to have some width and shape. Mapping it as an area makes it primarily a chunk of asphalt...that you happen to be able to drive along to get somewhere. The ideal situation would probably be to have users be able to enter either ways or areas, and have the server software understand the relationship between them, and convert between them. So if you enter a way, it automatically creates an implicit area around it with some default width. Nice client software might let you manually tweak that area. This aspect of GUIs is very hard to get right though: when there are automatic/implicit data structures that are occasionally customised. What happens if you customise the shape of the road, then re-route the way? There's never a very clean answer to that question. (Possibilities are, keep the area - even if it's out of sync; discard the area information; attempt to preserve some of the area information - even if it now makes no sense...) Steve _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
