Hi all, My findings so far: Attached are small demo files that show the problem with Basecamp routing. With demo.osm Basecamp refuses to route the shortest way in one direction and doesn't in the other when start and tartget are on the same side of road A. It also prefers the detour with "faster time" for one direction, with demo-more-than-32.osm it always takes the shorter way because the distance between the two ways is a bit longer. The problem also disappears when there is a curve on the ~30 m arc (mkgmap writes different NOD data for this) . I still have no idea if this is an error in the data written by mkgmap or if there is a special case in the Basecamp routing algo. While one can argue that a right turn can take long in a drive-on-left country one would expect that this should have no or only a small effect on the calculation of the "shorter distance". OTOH Garmin doesn't claim that it calculates the shortest route, it is only a "Route Preference". Options to use: --route --preserve-element-order --drive-on=left If you use option --drive-on=right the results are reverted, means, you have to also revert the route to see the same results. Maybe those who have an original routable Garmin map can try to find a similar case in their map and report if the routing works or not. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen@hotmail.com> Gesendet: Samstag, 11. Juli 2020 18:05 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Bad routing on eTrex and MapSource Hi Ticker, I still have no clue where to change something :( Routing works fine for pedestrian mode and all the shown values like length or directions look correct, so it seems that the encoded values are interpreted as expected. I've also tried things like mirroring all the data on the vertical axis. Results were exactly the same after I also changed drive-on=left to drive-on=right. Problem disappears when the length of the arc between node 712553226 and node 5691769367 is a bit longer, e.g. 33m instead of ~30m so that it is encoded with the next higher byte value. When I change the geometry so that the arc is even shorter it doesn't seem to help. It really looks like Garmin doesn't like to make to left turns within less than ~32 m when shortest route is selected and traffic mode is not pedestrian. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Samstag, 11. Juli 2020 13:20 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Bad routing on eTrex and MapSource Wow - that is a simplification. I was initially confused because both BaseCamp and Mapsource show the old, full map, despite it having been renamed, but show the routes between the 9 nodes in your minimal test map. Ticker On Fri, 2020-07-10 at 11:13 +0000, Gerd Petermann wrote:
Hi Ticker,
it seems to be related to the encoding of the heading / bearing data. I've reduced the test case to a few roads (see attached file) which still show the problem. When I rotate this small set of data a little bit the problem disappears.
Will continue later...
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen@hotmail.com> Gesendet: Freitag, 10. Juli 2020 09:28 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Bad routing on eTrex and MapSource
Hi Ticker,
OK, I've updated Basecamp to 4.7.2 now. When I change the car profile to "shortest way" I also see the long detour, so yes, that makes it more likely that mkgmap writes wrong data. Not sure if I tested this wtih 4.7.1
I'll try to find the trigger for this.
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Freitag, 10. Juli 2020 09:08 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Bad routing on eTrex and MapSource
Hi Gerd
There is something very wrong here with the routing here.
Apart from this example, I've never experienced the device taking a long detour to avoid right turns. Testing with BaseCamp and shortest distance on MapSource, the route goes the wrong way and makes a u -turn - see attached BaseCamp trace - do you see this behaviour.
What could be a similar problem I discovered the other day was a secondary road with a right turn into a alley to a car park. The device and MapSource wanted to turn into the alley, do a u-turn, then turn right out of the alley and continue on the road. BaseCamp took a 5 km detour to avoid going past the alley.
I've also attached my modified test script.
Ticker
On Thu, 2020-07-09 at 15:40 +0000, Gerd Petermann wrote:
Hi Ticker,
I also don't understand the results in MapSource but I could not find anything wrong in the img data. I also didn't see anything wrong in the route directions. What value looks suspicious to you? My current thinking is that you found an error in the Garmin software. I think it overweighs the two right turns (in a drive-on -left country)
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Donnerstag, 9. Juli 2020 17:12 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] Bad routing on eTrex and MapSource
Yes, setting drive on left changes the behaviour back to as described at 12:03 (but it don't why)
Ticker
On Thu, 2020-07-09 at 14:32 +0000, Gerd Petermann wrote:
Hi Ticker,
without bounds the program probably doesn't set the drive-on-left flag, so you should set option --drive-on=left to get similar results.
Gerd
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