OpenStreetMap
Ok so has anyone else found that their GPS doesn't recognise every junction.
It seams that when one road joins another at an acute angle my Garmin is unable to see it as a junction. I've got around this by placing another node on the joining way very close to the final node so as not to inturupt the look of the junction but make the final part of the way right angles so that my Garmin tells me to turn left/right.
Has anyone else solved this with a different method? I thought about making the final node a stop sign but this might not always be the case....
For the example shown it's more confusing because the road Calverley Park Gardens (A264) joins Pembury Road (A264) but I've seen the same behavoir at other junctions
Discussion
Comment from RichardB on 14 July 2009 at 21:17
Whilst it's obviously frustrating - can I suggest you change the nodes to make right angles on a local copy of the data - rather than in the database?
Actually editing the data to achieve a desired result is not generally the done thing - it's not much different from tagging for the renderer.
What happens when you use the Mkgmap software to convert it into the right format is I think some roads get merged in the pre-processing. There must be some tolerance on the angle to decide if one road carries on from another (there are many thousands of split roads where you would not want an instruction).
There has been a lot of talk about using relations to create some sort of a priority path - (but I don't think this has really taken off yet) - to clear up confusion where two ways have the same name but you must turn off to travel between them.
Comment from Rhubarb on 15 July 2009 at 03:29
This sounds like it should be a bug to be submitted to mkgmap:
osm.wiki/Mkgmap
As RichardB writes, it's best not to change the OSM global database to get this to work, as it's ugly and is just a work-around.
Better to get this fixed at what I'm guessing is the source of the problem (Mkgmap) - then we can all benefit from better routing on garmin units from existing OSM data.
- Thanks for pointing this out, as this may well be a bug that's occured with routing for me - though I hadn't had time to try out work out what the bug was.
Comment from burto on 15 July 2009 at 07:39
Yes, you could say that this is a bug in mkgmap and it has been discussed a few times on the mkgmap dev mailing list. Unfortunately, there are no plans in hand for fixing this due to lack of knowledge of the Garmin data format. If we knew how to fix it, it would have been done by now.
It's not, as Richard suggests, the case that we are filtering out information. It's more that we are not putting in some missing stuff that makes the GPS recognise the presence of the junction.
I agree with the other comments that you should not adjust the OSM data to make the Garmin map work right.
Comment from Welshie on 18 July 2009 at 20:56
Is it not something silly like you have told your Garmin to avoid U turns and it interprets acute angles as such?
Comment from DCWells on 19 July 2009 at 11:53
Thanks for all the comments, I can fully appretiate not altering the global database to achieve workarounds. I am finding it good practice to work on my own OSM files now to test faults with routing in my area, this change was loaded to global but I'll refrain from that in future.
I know one day some clever fella will figure it out or maybe I'll get some time to have a look.