Island Subnetworks


#1

Looks like this Island has been removed:
https://graphhopper.com/maps/?point=39.577975%2C2.307858&point=39.596248%2C2.335432&vehicle=foot&locale=de-DE&elevation=true&layer=Omniscale

Is it because of the network size? I checked https://github.com/graphhopper/graphhopper/blob/master/core/src/main/java/com/graphhopper/routing/util/PrepareRoutingSubnetworks.java and would like to know what is actually the unit of minNetworkSize? The javadoc talks about nodes but I I would guess that the island has more than 200 nodes (If the default value was used for preparation).

Same happened in my import so I would rule out a temporary data problem.

Jan


0.5.0: Connection between locations not found
#2

I don’t think this island has more than 200 junctions but you can easily cut the osm and see after import


#3

Ups, forgot some of your questions, sorry.

Yes, that should be because of your network size and the unit is junctions or ‘tower nodes’ as we call them.

Would you mind to cut the osm and see what happens if you specify a smaller value for both network sizes?


#4

Ok if the unit is tower nodes than it could be that this criteria is not sufficient to include real islands and exclude the typical private or disconnected subnetworks we find in (larger) cities. What do you think?
The island is just an example. I don’t want to invest too much time into this specific case, hence to cutting and re-importing from my side.


#5

It is of course not perfect but reasonable. A better approach is also necessary for the flexibility improvements in the next months where no preprocessing can take place. There are several approaches to do this, so I would like to avoid tweaking subnetwork removal with heuristics or something to detect islands versus inner city stuff for now.