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When selecting "Minimize Distance", the result conforms with the expectations: the shortest route is selected by the Garmin Oregon 600. But with "Minimize Time", things are different. It is not at all the route with the shortest time. By setting a "Via Point", I can have it calculating my preferred route, which is calculated with a shorter time. I.e. despite the title of my selection, the device did not minimize time. Example: Travel from Bayreuth to Erlangen. The Oregon calculates a long route via motorways, 98.4 km, at 67 minutes. With a Via Point west of Ebermannstadt, the distance is shortened to 64.9 km, but also the time is now 60 minutes only. The longer distance might be appropriate - but I find the longer time strange. It is 7 minutes / 10% longer by time! Travelling along my preferred route, the device has to recalculate several times, with some more such results. E.g. from Obernsees, it prefers 86.4 km at 56 minutes over a route of 51.8 km at 46 minutes - 10 minutes or 20% longer! From east of Ebermannstadt, it prefers 39.8 km at 30 minutes over 29 km at 26 minutes. All the preferred routes use long sections of motorways, and reduce the sections on roads with low road_class attribute(road_class=2; lower values are not present in my preferred route). What are your experiences? How much is the "penalty" for low road_class values? Are still other factors important?
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Hi Bernhard, Garmin has 2 version of routing algorithm, older and newer. Older is used by Mapsource, older nuvi, probably by outdoor devices. Newer algorithm is used by BaseCamp and last 2-3 generations of nuvi. Newer algorithm is designed for speed of calculation rather than quality of results. Finding fastest way is based on road classes. At longer distances device uses only class 4 roads ignoring shortcuts with lower class. That's why you can optimize route manually. Older algorithm is more precise, it can use lower class roads, when class 4 roads are missing. Calculations are longer. But probably you still can find better route manually. -- Best regards, Andrzej
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Cze´sć Andrzej, thanks for this (bad) information. Looks like the Oregon 600 (an outdoor device) uses the newer algorithm. Well, it means, I can now stop optimizing for the "correct" route, and perhaps rather try to "optimize" the calculated time for the selected route (i.e. get it closer to my driving times)... Am 16.08.2014 14:46, schrieb Andrzej Popowski:
Hi Bernhard,
Garmin has 2 version of routing algorithm, older and newer. Older is used by Mapsource, older nuvi, probably by outdoor devices. Newer algorithm is used by BaseCamp and last 2-3 generations of nuvi.
Newer algorithm is designed for speed of calculation rather than quality of results. Finding fastest way is based on road classes. At longer distances device uses only class 4 roads ignoring shortcuts with lower class. That's why you can optimize route manually.
Older algorithm is more precise, it can use lower class roads, when class 4 roads are missing. Calculations are longer. But probably you still can find better route manually.
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I experienced the same issue with a my new Montana 600... I first realized it when I miss a turn and magically I gained 5 mins. Now I guess I know why! On Tue, Aug 19, 2014 at 6:56 PM, Bernhard Hiller <bhil@gmx.de> wrote:
Cze´sć Andrzej,
thanks for this (bad) information. Looks like the Oregon 600 (an outdoor device) uses the newer algorithm. Well, it means, I can now stop optimizing for the "correct" route, and perhaps rather try to "optimize" the calculated time for the selected route (i.e. get it closer to my driving times)...
Am 16.08.2014 14:46, schrieb Andrzej Popowski:
Hi Bernhard,
Garmin has 2 version of routing algorithm, older and newer. Older is used by Mapsource, older nuvi, probably by outdoor devices. Newer algorithm is used by BaseCamp and last 2-3 generations of nuvi.
Newer algorithm is designed for speed of calculation rather than quality of results. Finding fastest way is based on road classes. At longer distances device uses only class 4 roads ignoring shortcuts with lower class. That's why you can optimize route manually.
Older algorithm is more precise, it can use lower class roads, when class 4 roads are missing. Calculations are longer. But probably you still can find better route manually.
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participants (3)
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Andrzej Popowski
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Bernhard Hiller
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Enrico Liboni