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[mkgmap-dev] Wrong route on roundabout

From Gerd Petermann gpetermann_muenchen at hotmail.com on Thu May 30 09:00:47 BST 2024

Hi Oskar,

I think the mapping of the roundabout is part of the problem. It's diameter is a bit too small and therefore the
connection of the way https://www.openstreetmap.org/way/78515591
is not on the roundabout but on  https://www.openstreetmap.org/way/78515465

I think the roundabout should be enlarged and way 78515591  should be connected to it. I also wonder why this short part of the road doesn't have the name=Kalda tag.
The router Valhalla is rather new, maybe you should report the issue to its developers.

Anyhow, I don't see the wrong results with a small Garmin map compiled for that area (tested with MapSource and Basecamp), also not with your map loaded into Basecamp.
I get the expected route similar to that from Graphhopper.
You may want to add 
to your options, but that is not important here.
Maybe you have a special configuration on your device?


P.S. Karl modifed the OSM data while I was writing my reply, so some comments may no longer make sense, but I hope you get the idea.

Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Oskar Ohakas <oskar.ohakas at proton.me>
Gesendet: Donnerstag, 30. Mai 2024 06:52
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: [mkgmap-dev] Wrong route on roundabout


I compiled my first gmapsupp.img and on test drive garmin offered an obviously wrong route on a roundabout (garmin.jpg). On OpenStreetMap i get the same wrong route with algorithm Car (Valhalla), but Bicycle (Valhalla) and other routing algorithms will give the correct route.
I followed the instructions from

mkgmap \
    --route \
    --add-pois-to-areas \
    --bounds=bounds \
    --index \
    --gmapsupp \

Have I missed an important option? Is it possible to fix the problem in compilation phase or is it something confusing for Garmin algorithm in OpenStreetMap data? If it helps, then I have uploaded the gmapsupp.img for possible inspection to the address https://0x0.st/XNpC.img/gmapsupp.img

Any helpful insights are welcome.

Oskar Ohakas

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