[mkgmap-dev] About routing options, Mapsource and speed limit

Mon Feb 23 19:27:47 GMT 2009

Hi David,

It's nice that you've chosen for your example an area that I map.
Since I only just last weekend created a routable map of Ireland that
has worked for me quite well, I thought it worth investigating your
test route.

What I found:

My Garmin Nuvi routed me as you would expect: for a fast route, it
routed me over the M4 and M6 motorways, leaving at the Tyrelspass
junction. For a short route it had me leave at the first M6 junction
and take the old road (R446). In both cases, the device respected the
one-way restrictions on the motorway.

As you have presumably checked, the oneway status of the motorway ways
in the vicinity of the River Boyne crossing you depict is correct.

Although the M4 has a toll between Kilcock and Enfield (nodes tagged
highway=toll_booth), the device does not avoid it when instructed to
avoid tolls. However, I'm not aware whether toll avoidance support is
expected to be present or even understood in the data model. It seems
to have no bearing on this example.

My map is derived from a single planet dump of all Ireland. That is, I
am not routing across tile boundaries.

I don't think speed limits can be a factor here, since no explicit
limits are set for the roads in question.

Have you tried your map on an actual device? I haven't (yet) tried my
map on Mapsource.

Now would probably be a good time to thank very much those responsible
for making the routing work, and particularly for the work tracking
down the pink line of death. A whole map of Ireland, routable, from
OSM data currently fits within 10MB and seems to work pretty well.

One question, though, that someone may know the answer to. Roundabouts
seem not to be drawn in the correct road class, but always in the same
style (have to load up qlandkarte to check which, but with default
styling it renders in a similar orange to secondary, primary and
trunk). Is there a Garmin restriction behind this or can it be fixed
with suitable styling?

Dermot

2009/2/23 David <david.tlp at orange.fr>:
> The option "route" in a file called with -c option does not work for me. I
> have to launch "java -enableassertions -Xmx512M -jar mkgmap.jar --net
> --route -c options.txt mymap.osm" if I want a routable map.
>
> Since someone set by default TDB v4, I can build routable map, thank you. It
> is like "--tdbfile=tdb-v4" did never work for me since revision 86x.
>
> I test the Ireland map with Mapsource and I observe strange results in route
> calculation :
> With shortest length selected :
> Major highways are systematically avoid despite I setup Mpasource with
> "choose major highways first".
> Major highways are used only with "choose minor roads"
> It seems to be an inversion bug with "shortest length" only. Moreover, the
> distance calculated is bigger (68.2km in 8h21min51s !!!) than when I choose
> the shortest time (62.4km in 8h18min11s !!!)
> The one way restriction on motorway for example is not taken in account. I
> did my tests on M4 motorway between Lucan and Tyrrelspass.
> Is it a hidden bug on speed limit with an incidence on one way ?
> On screenshots below, you can also see a hole on highway. I did not found
> anything wrong in data...
>
> Here are screenshots (there is no inversion between pictures):
> setup with "choose major highways first" (motorway M4 is in orange):
>
>
> Setup with "choose minor roads first" (the hole in the route should come
> from map data) :
>
>
> Wrong way in Mapsource :
>
>
> Good way in Mapedit :
>
>
>
>
>
>
>
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