>>> >>> I noticed that some Garmin maps display 1:1 to openstreetmap data, >>> but on route calculation show up to 10% shorter distance. Maybe here >>> only routing nodes are simplifed (straighter line). >> >> Sorry, could you explain in more detail? I'm not sure what you mean >> here. >> 'Simplifiing routing nodes' is the thing, which tries Mark with his >> bogus node patch. > Well I noticed this on a serpentine way in the Swiss Alps. > > I routed over Topo Swiss v2 and distance was 2.3km, then on > Openstreetmap mkgmap created map 2.8km. Though when putting the maps > transparent above each other, there was nearly no difference to tell > in the shape of the ways. From plain eye openstreetmap seemed to be > shorter even. Therefore I assumed that the way it was showing was > longer than the way the routing happened on. Also my bicycle computer > showed 3.1km on the supposedly 2.3km part of the route. > . > Thats interesting. The distance for routing is contained in the routing tables and these are not touched from me in any patch. I really don't know, as I have never looked into it, but here is an assumption: I think the arcs conains the distnace from node to node. Maybe here is the direct line from node to node calculated and not the real length from the winding serpentine.
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