[mkgmap-dev] Route calculation error introduced in r1337:1343

Tue Nov 10 21:03:36 GMT 2009

Hi Marko,

> About a week ago, I began experiencing route calculation errors on the
> Edge 705.  I cannot calculate a bicycle or walking route from my home
> (2 km east from the Korso railway stop) to the Pasila railway station
> or the center of Helsinki (a few km further south).
> 
> Because a Nüvi user complained about broken car routing west from Helsinki,
> with no obvious error in the OSM data, I decided to test earlier versions
> of mkgmap.  Dropping the option --adjust-turn-headings did not make any
> difference.  I just rebuilt and tested the following mkgmap revisions:
> 
> r1319: ok
> r1331: ok
> r1337: ok
> r1343: route calculation error
> 
> In addition to these, I have built (broken) maps with r1344, r1362, and r1364.
> 
> Should I track down the earliest buggy revision, or is the r1337:1343 range
> of revisions specific enough?

That's all very interesting. I'll tell you why. I have been working on
another patch that removes redundant nodes from ways. When I use that
patch, the maps are fine on mapsource and the etrex but with the nuvi
they break the routing in a completely odd way. It just thinks that it
can't get past a certain point even though there's no good reason not
to.

I wonder if this is the same problem that you are seeing.

Could you please try reducing the value of MAX_ARC_LENGTH (in
StyledConverter.java), initially right back to 25Km as that's what it's
been for a long time and see if it makes any difference for you. If
that doesn't help, you could try using smaller values for some of the
other constants there.

Cheers,

Mark