R: [mkgmap-dev] Maps not for Cars and sharp-turns, U-Turns
Made some test. during fastest route serching, garmin gives a time penalty to turns. time penalty seems propotional to road speed so I think it just calculates a speed reduction due to turn and then a linear increase of speed up to the road speed. for a steep 15° turn I got 357 second penalty on a motorway (road_speed=6 i.e 108km/h) and 237 second penalty on a primary (road_speed=4 i.e. 72km/h) as the angle widens, the penalty is reduced (at 45° is about 1/3 the above values, at 90° about 1/8) Ciao, Marco. --- Gio 28/5/09, Felix Hartmann <extremecarver@googlemail.com> ha scritto:
Da: Felix Hartmann <extremecarver@googlemail.com> Oggetto: [mkgmap-dev] Maps not for Cars and sharp-turns, U-Turns A: "Development list for mkgmap" <mkgmap-dev@lists.mkgmap.org.uk> Data: Giovedì 28 maggio 2009, 23:17 After playing around a bit with maps and getting really confused why on some ways I could not route along with car/motorcycle setting, even though all access restrictions were sorted out, I found out that in case of very low angle of roads meeting, in car/motorcycle setting huge detours maybe made just to turn around.
This is quite impractical as the best routing performance can be achieved with the car/motorcycle setting when writing the maps in such a way that bicycle use is assumed to be used as car/motorcycle. Using a bicycle there is no need to prohibit any kind of u-turn, but I think we can't get this out of the garmin programming but by changing the data source. Has anyone any idea how we could sort out this problem with preprocessing?
Actually this might be usefull for car/motorcycle uses as well. It would be better to rely on turn-restrictions than on the garmin GPS simply deciding that at some place turning is impossible and making a detour to turn! I don't know the angle but I think if the meeting angle is lower than somewhere around 20° this happens. So roads meeting would need to be changed to meet at bigger angles than 20°. To really find out the angle upon which Garmin GPS/Mapsource decide a car can't turn (note avoid U-turn is not activated of course) would need some test maps however.
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Interesting experiments, thank you! Maybe, we should add these results to the Wiki? http://wiki.openstreetmap.org/wiki/Mkgmap/routing Is there any chance to get influence on these penalty values? I.e., is there a penalty factor included in gmapsupp.img file which can be adjusted? OK, this would be a search for the needle in a haystack... Markus -------- Original-Nachricht --------
Datum: Thu, 28 May 2009 23:03:19 +0000 (GMT) Von: Marco Certelli <marco_certelli@yahoo.it> An: f.hartmann@fh-krems.eu, Development list for mkgmap <mkgmap-dev@lists.mkgmap.org.uk> Betreff: R: [mkgmap-dev] Maps not for Cars and sharp-turns, U-Turns
Made some test.
during fastest route serching, garmin gives a time penalty to turns. time penalty seems propotional to road speed so I think it just calculates a speed reduction due to turn and then a linear increase of speed up to the road speed.
for a steep 15° turn I got 357 second penalty on a motorway (road_speed=6 i.e 108km/h) and 237 second penalty on a primary (road_speed=4 i.e. 72km/h)
as the angle widens, the penalty is reduced (at 45° is about 1/3 the above values, at 90° about 1/8)
Ciao, Marco.
--- Gio 28/5/09, Felix Hartmann <extremecarver@googlemail.com> ha scritto:
Da: Felix Hartmann <extremecarver@googlemail.com> Oggetto: [mkgmap-dev] Maps not for Cars and sharp-turns, U-Turns A: "Development list for mkgmap" <mkgmap-dev@lists.mkgmap.org.uk> Data: Giovedì 28 maggio 2009, 23:17 After playing around a bit with maps and getting really confused why on some ways I could not route along with car/motorcycle setting, even though all access restrictions were sorted out, I found out that in case of very low angle of roads meeting, in car/motorcycle setting huge detours maybe made just to turn around.
This is quite impractical as the best routing performance can be achieved with the car/motorcycle setting when writing the maps in such a way that bicycle use is assumed to be used as car/motorcycle. Using a bicycle there is no need to prohibit any kind of u-turn, but I think we can't get this out of the garmin programming but by changing the data source. Has anyone any idea how we could sort out this problem with preprocessing?
Actually this might be usefull for car/motorcycle uses as well. It would be better to rely on turn-restrictions than on the garmin GPS simply deciding that at some place turning is impossible and making a detour to turn! I don't know the angle but I think if the meeting angle is lower than somewhere around 20° this happens. So roads meeting would need to be changed to meet at bigger angles than 20°. To really find out the angle upon which Garmin GPS/Mapsource decide a car can't turn (note avoid U-turn is not activated of course) would need some test maps however.
_______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
_______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
I think these penalties are in general usefull for routing optimization. On an normal 90° crossing they will be 30 sec on a 50 km/h street, which seems quite reasonable for me for car routing. This helps the routing algorithm to prefer straight lines without a lot of street changes. I'm astonished by the values. 357 sec are 6 minutes! I have tried to interpret your values and observations: Seems to me, that the penalty gets calculated by a formula similar to ((180°/x)-1)*3.3*roadSpeed. So these values are extreme values because of the extreme situation. An 15° corner on an highway is really not usual... (and I think it would need 6 minutes to sort out the traffic :-) Regards, Johann Marco Certelli schrieb:
Made some test.
during fastest route serching, garmin gives a time penalty to turns. time penalty seems propotional to road speed so I think it just calculates a speed reduction due to turn and then a linear increase of speed up to the road speed.
for a steep 15° turn I got 357 second penalty on a motorway (road_speed=6 i.e 108km/h) and 237 second penalty on a primary (road_speed=4 i.e. 72km/h)
as the angle widens, the penalty is reduced (at 45° is about 1/3 the above values, at 90° about 1/8)
Ciao, Marco.
--- Gio 28/5/09, Felix Hartmann <extremecarver@googlemail.com> ha scritto:
participants (3)
-
gypakk＠gmx.eu -
Johann Gail -
Marco Certelli