On Wed, Jul 8, 2009 at 12:05 PM, Stefan de Konink<[email protected]> wrote: > On Wed, 8 Jul 2009, Matt Amos wrote: > >> On Tue, Jul 7, 2009 at 10:26 PM, Stefan de Konink<[email protected]> wrote: >> > SteveC wrote: >> >> inventing nodes, ways, segments (remember them?) >> > >> > You *did not* invent the spaghetti model, please give credit to the >> > original inventor Stan Aronoff, in Geographic information systems: A >> > management perspective (1989). >> >> actually, OSM doesn't use the spaghetti model. according to [1,2], >> Aronoff's spaghetti model treats points as coordinates and lines as >> lists of coordinates > > Isn't this exactly how segments and ways are stored within OSM? An XML > subtree referencing to points (thus lower diminensional objects)?
from those references, it seems that the spaghetti model includes coordinates directly, rather than referencing a lower dimensional object by ID. apparently it's called the spaghetti model because each way is independent, like spaghetti strands (presumably as opposed to potato waffles or something "joined"). spaghetti model - coordinates are directly included, topology is implicit. <node lat=y lon=x/> <way><node lat=y1 lon=x1/><node lat=y2 lon=x2/><node lat=y3 lon=y3/></way> graph theory model - coordinates are logically referenced, topology is explicit. <node id=1 lat=y lon=x/> <way id=1><node ref=1/><node ref=2/><node ref=3/></way> OSM uses the latter. >> - basically what the OGC's "simple features >> architecture" [3] uses - and there's no explicit connectivity. OSM, on >> the other hand, uses a topological model which comes from a graph >> theory background, so really we should be crediting Leonhard Euler. > > Always good to credit him :) yep. he was a total genius - invented a whole new branch of mathematics without which we wouldn't have amazon/netflix recommendations ;-) cheers, matt _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
