[mkgmap-dev] Problem with --adjust-turn-headings

Tue Feb 9 08:56:56 GMT 2010

Hi Apollinaris,

> found a problem in the osm data. there was a short bridge with the name of the exit instead of the motorway name. the turn instruction was exactly as expected according to your implementation.

OK.

> I have another interesting one here
> http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=sacramento&sll=37.0625,-95.677068&sspn=58.294644,106.699219&ie=UTF8&hq=&hnear=Sacramento,+California&ll=38.573956,-121.578934&spn=0.000448,0.000814&t=k&z=21&layer=c&cbll=38.573604,-121.581104&panoid=e4tOr0puxhW-8sDps67wRA&cbp=12,89.03,,0,18.64
> or in osm
> http://www.openstreetmap.org/?lat=38.57493&lon=-121.5694&zoom=16&layers=B000FTFT
> Starting at this position I-80 has 3 lanes, to continue on I-80 a keep right instruction is required. But because of same name and same ref no instruction is given. Now adding a through_route relation is an option. But the straight route is also named I-80 BUS and I think in this case an instruction should be given for both routes because the importance is equal for both routes
> Is it possible at all to do this in Garmin format? 

Some Garmin GPS units can tell you which lane to be in (lane
assist?) but we don't know how to encode that info. Pity, as that's just
what you need here.

But looking at the sat pic, I would think that adding a through_route
relation is reasonable because more of the road lanes continue on
to the I-80 BUS than they do to the I-80.

Ah, a subtle point here is that it will probably tell you to turn right
rather than keep right at the junction. But I can probably fix that by
making mkgmap notice that all of the roads are motorways and so reduce
the amount of heading change. But in the meantime, if you want to add
that relation (and you will need my patch to mkgmap, of course) and
test what happens, it will be interesting to know.

> 
> And again there is a navi failing this test. Google navi on Android doesn't announce a keep right instruction and I bet 50% who rely on their navi will miss the right turn.

Very likely, so we should be able to do better than that!

Cheers,

Mark