[OSRM-talk] Island hopping

Zenon Panoussis oracle at provocation.net
Tue Oct 14 00:44:11 UTC 2014


I've been testing OSRM on Greece and I run into some oddities.
I use start: ιεράπετρα, end: χαλκίδα and they are understood
correctly and transformed into something perfectly reasonable.
But the route goes to Piraeus, then to Kythnos, from there to
Tziá (Kea) and then finally heads in the right direction through
Lavrio towards Chalkida:

http://s2.postimg.org/3t8nqy949/ierapetra_chalkida0.png

The cause of this can be seen here:

http://s29.postimg.org/h8ebb5g9j/ierapetra_chalkida1.png

The routes from Heraklion and Kythnos do not fully connect to
the harbour (this is an OSM mapping error), but they do connect
to each-other at the entrance to Piraeus port. The rest is OSRM
trying to do its job as best it can.

However, this is also a bug in OSRM: it calculates routes that
require a mid-sea change of ship. It shouldn't. There needs to
be some logic that says "if at_sea: ignore_all_intersections"
to get rid of this behaviour.

Apart from that, island hopping in Greece can be really great.
Especially if you avoid the tourist traps and go to places like
Kythnos and Tziá instead.

Z




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