[GraphHopper] Disconnected areas

[Peter K]

Hi Ludwig,

> Hi Peter,
>
> fiddling with that parameter seems to do the trick. I managed to get
> routing to work for Naxos with a value of 500, but had to drop this
> further to 200 to get routing on some even smaller islands.

Good and bad ;(!

> For me at this point the question is what the motivation is to exlude
> certain areas at all. Even if this was a private area (behind a
> barrier) why exclude it from roiuting?

Because you won't find a route if one coordinate of the route is inside
and one is outside. E.g. if you would search 'Dresden' (or a lot more
locations like 'moskau' etc) the GPS coordinate would be exactly within
such an area and you won't find a route. Also routing within
private/restricted/forestry areas is in my opinion not really useful for
a public site. Additionally there are OSM bugs which leads to those
subnetworks.

Do you have another idea? One could try to solve this via a changed
routing or location-lookup but this looks ugly to me.

I've lowered this value to 200 and made it configurable via
prepare.minNetworkSize:
https://github.com/graphhopper/graphhopper/issues/86

Regards,
Peter.