[mkgmap-dev] Thoughts on OSM routing

Tue Feb 17 13:26:00 GMT 2009

0> In article <20090217122810.774eb3aa at crow>,
0> Mark Burton <URL:mailto:markb at ordern.com> ("Mark") wrote:

Mark> The roundabout exit problem can be fixed by using
Mark> the --frig-roundabouts option.  It's rather a hack and may
Mark> actually make some roundabouts suffer from the problem when,
Mark> before, they didn't but, at this time, it's all we have.

I understand that; thanks for reiterating, though.

As I said, bad source data is more of an issue - I'm cleaning up quite
a bit as I go.

One thing that caught me by surprise was approaching a roundabout and
just being told to keep left - it wasn't until I reached the splitter
island that I got given the roundabout exit to take.  I guess this is
the opposite of the missing-exits problem, in that the island was
large enough to count as a separate road for the eTrex's purposes.

One thing I do have a concern about is mixing speed rules into the lines
file - I've patched my style as instructed, but now all roundabouts are
drawn the same, because there's a rule for roundabouts for speed purposes.
(I'm too lazy to introduce roundabout rules for each highway class).  I
think that this probably needs a re-think, because it would be nice to
combine information to give a better resultant speed guess (including
features such as traffic signals, number of lanes, etc - and for roads in
"place=*" as described[1] on the OSM wiki).

[1] <URL: http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Maxspeed >