On Tue, 03 Nov 2009 12:00:03 +0100, Marc Coevoet <[email protected]> wrote: > Dennis Luxen schreef: >>> I've always asked myself why we wouldn't try some quadtree algoritm >>> for >>> parsing/routing/filing our data... >>> >> >> Well, Quad-Trees don't help you much when it comes to routing. It's a >> data structure that helps answering queries that ask for a nearest >> neighbor to some coordinate. > > They use quadtrees at google (for display), I do not know if it is for > routing, but.. (if they use quadtrees at google, it is a reason not to > study quadtrees here ;-) "I am a shareholder "...
They use something very different for routing. An aproach based on map-reduce that works very well for their scale but does not scale down to anything below 1 datacenter. ;) > I have the idea routing algos sometimes take too much roads of no > importance, and arrive where the traffic shouldn't come. what routers with what routing-algorithms, target-metric and parameters did you use? the shortest route for example will almost always use roads of low importance as anything else will just not be the shortest route. > if you organise a hierarchy of roads, say highways, then "route > nationale", then "departementale", you can always prefer to take > highways instead of nationales, etc, for a LONG journey. And I guess > there is a relation between "hierarchy" and "dichotomy" somewhere. > Where do they meet ?? I have no idea what a "route nationale" and "departementale" are but we already have a hirachy expressed via the "highway"-tag. Marcus _______________________________________________ Routing mailing list [email protected] http://lists.openstreetmap.org/listinfo/routing
