Frederik Ramm schrieb: > Hi, > > just played with Google routing from one side of London to the > other, and found it tends to display the fastest (often M25) route > first, but then offer a number of "alternatives", seemingly named after > the road that makes up the largest portion. So in addition to the > initial M25 route, you immediately get "M4 (xyz minutes)" and others. I > wonder how it is done, algorithmically. It must be more than just the > shortest and the fastest route. Does it perhaps store which routes > people print after playing aroung with via points, and use that, or > something?
>From what I could find they seem to employ a database of fastest sub-routes to break down routing to their usual mapreduce-algorithm. Can`t find the paper right now. You could do such a thing yourself using e.g. apache hadoop but it only makes sense if LOTS of routes are to be calculated. Marcus _______________________________________________ Routing mailing list [email protected] http://lists.openstreetmap.org/listinfo/routing
