What I take away is hc=1.2 does not ever result in any significant routing error (where error is failure to match 1.0), of course in the cases you tried.
hc=1.3 is almost always non-erroneous, and the time saving from 1.5 to 1.3 is never important I don't 100% follow the "need 1.2 to be safe for economic route". Those routes don't necessarily look better than the 1.3, and you don't have the "economic cost", because osmand doesn't expose it. In the second example, the 1.2 is 164km and the 1.3 is 168km, but at the cost of 15m. But the economic cost values could be only a factor of 1.0001 apart. So I would not be upset with that "error". But I see your point with the metric of "did the route at 1.3 exactly match the 1.2 route (which is exactly the 1.0 route) as something you can say definitively. In ad hoc networks (computers talking over radio), there is an important paper that proposes a way to evaluate routing algorithms. The basic problem is that if every node has complete, up-to-date state information, then you can compute routes that are by definition optimal. But sending that state information takes up capacity. So the definition of the best routing algorithm is one that minimizes total messages sent to maintain routing state + extra hops in delivery (in that a message sent 11 hops when perfect information would have sent it 10 hops gets charged as an extra message) This leads to wanting less information if it doesn't hurt accuracy more than the savings. So if you think about getting in your car and pushing the calculate button, and then when there's a route starting to drive (since at least here you cannot touch the phone to recmopute routes once driving), then the metrics would be the travel distance and the sum of computation time and driving time. >From your research, I think I'll just use 1.3, and maybe save a 1.5 profile for really long routes. Thanks for doing this work! As an aside: long ago I started using shortest rather than fastest on a garmin handheld for driving, and found that mostly the routes were much shorter and only slightly more time (not in the city, where you have endless opportunities to make 3 extra turns and save 2m distance; where I am there just aren't that many extra roads). I'm a bit careful about these, but I found several good ways to travel that I didn't know about before, compared to usung the ~motorways. This makes me want a metric which is partly based on time and partly based on distance. Essentially, would I want to save 1km in distance at a cost of 1min in time? Hard call, but for 1m extra I would want to save 10km, and I would not want to save 100m. I might guess at 2km/min I'd want to save distance and add time. One could add a blend of fuel use to this too of course. -- You received this message because you are subscribed to the Google Groups "OsmAnd" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/osmand/rmi7dzqdbtg.fsf%40s1.lexort.com.
