Mark Burton wrote: 
Felix,
  
  
After playing around a bit on my Vista HCx I did notice slightly 
different routing too. The maximum distance that it manages without 
"route calculation error" did not change however.
    

On the HCx, I just tried an 800Km route from where I live to Thurso and
it took quite a while (stuck on 100% for a minute or two) but it did
eventually calculate a sensible route.
Well that's taking big streets. With my maps I'm happy when it routes 10-40km on the Vista HCx (or max about 50 turns), and 40-150km in Mapsource (or max about 150turns).

The only way to really improve this is in my opinion to remove sharp turns on intersections - what we talked about last week. Then Mapsource will route on for long, long distances and the Vista HCx will go up to 100 turns (or say 20-40km in really densely mapped areas). Vista HCx cannot route over more than 100 turns without Via Points from what is my knowledge, so that boundary cannot be removed.
  
Today's offering includes the table A tweak but it also increases one
of the limits that determine when a route centre needs to be
sub-divided. As far as I can tell, the limit was somewhat smaller than
it should have been. So with this patch, fewer routing centres should
be required (obviously depends on the map data).
      
Routing in Mapsource is now different too. So far I have found one route 
that does not calculate with the old version, but with the new. The 
difference is however 2-3 more turns, so no drastical improvement. Maybe 
some routes also degrade?
    

I guess that is possible but I would hope that the overall effect is
beneficial. I'm (optimistically) working on the theory that increasing
the size of the route centres makes the route calculation
easier/quicker. That could, of course, be complete rubbish.
I think this is correct, but will not help much for non car centric maps (car centric in the way that motorways have few intersections, and have no sharp turns on intersections). For car centric maps the patches might help more, because here you route over many tiles and therefore the more efficient the underlying data, the better.
With the current patch, my GB map is around 172 MB compared to 180
without so the space saving is worth having if not dramatic.

Cheers,

Mark


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