On 7 September 2013 14:46, Philip Barnes <p...@trigpoint.me.uk> wrote:
> > Streetmaps do tend to be abstractions of the real world, and > openstreetmap ceased to be be a mere streetmap several years ago, and is > a far far better map than a mere streetmap can ever be. The word > streetmap implies urban, cities. OS maps are abstractions even when not dealing with streets. The other problems with micro-mapping are: - the transition between higher and lower levels of abstraction. I have considered mapping certain road areas as areas, because the line approximation loses important information, but, unless a road joins an area perpendicularly, this doesn't work well in the transition region; - with things like sidewalks, there is usually a fixed distance between the two pedestrian ways and the vehicle way, but the current data structure cannot represent that, and the current tooling doesn't support it very well, so if everyone started mapping sidewalks explicitly, there would be big maintenance problems (I've just seen a transition case where a road both has a separate footpath, with cycle access and the road itself is marked as having parallel cycle tracks); - routing software can no longer just operate on a network of edges and nodes, but needs to know that your can normally cross from one sidewalk to the other, at arbitrary places. (currently I have seen explicit footway crossings, where no physical features exists, being inserted to get round this one. Basically, the abstraction is adding value, by showing that the the sidewalks are related. _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
