[mkgmap-dev] gpx track files do not work on routable maps

Sun Mar 4 18:36:34 GMT 2012

> I have been able to do further testing on my Edge 705. Although the
> routing "on the fly" works on the unit, I cannot reliably use a GPX
> track file, either created from a mapping website or using a previous
> ride in the device history. Either the Begin and End points merge,

That is very strange, does anyone else see that on any other device?

> Could it be a problem in the route building in mkgmap? I had a look at
> the code, and identified some files where the route are built, but I
> would like to know more how this works. Is there any way I can help
> improve it?

The routing network that is produced is like a simplified version of
the roads in the map, with only links between the different roads.
There is extra information about the kind of road, expected speed,
various restrictions etc.

There are two stages, first to get the information from the OSM data,
which is in some ways the hardest part.
There is then how it is represented in the map tile, which is
of course complicated by the fact that the format is only
partially understood.

The only documentation of what is known about this format
apart from the code is at:

   http://svn.parabola.me.uk/display/trunk/doc/nod.txt

Actual routing is done by the device, so is entirely out of our
control.

..Steve