[GraphHopper] Disconnected areas

[Peter K]

Hi Ludwig,

probably we are a bit too aggressive with removing subareas! Ie. it
could be that the island is 'too small' for graphhopper and will be
removed (as graphhopper thinks this is a subnetwork hidden after e.g.
barriers etc). Please change PrepareRoutingSubnetworks.minNetworkSize to
something smaller than 3000 like 500 and let me know if this helps.

Kind Regards,
Peter.

> Thanks for your quick reply, I only had time to look into this again now.
>
> When I read your reply, I assumed that maybe the points I chose for
> illustration of the problem were too close together or maybe on the
> same road, but with my larger area I cannot get any routing to work on
> Naxos and I do get the same errors on the graphhopper website, even if
> I choose distant points clearly on different roads.
>
> However, if I just choose a smaller area to create the routing data,
> then the routing starts working. There is no other change to anything.
> Boundaries of smaller area as given in original mail.
>
> Example: 37.120359,25.410004 to 37.1,25.38 does not work on the
> extended area (and does not work on the website), but for the smaller
> routing area it works. See screenshot.
>
> I have not made any effort to understand how the routing works, but my
> hunch was that it is disconnected areas (in this case multiple
> islands) that cause the problem. Is that even remotely possible?


>
>
>
>
> On 15 September 2013 03:17, Peter K <peathal at yahoo.de
> <mailto:peathal at yahoo.de>> wrote:
>
>     Hi Ludwig,
>
>     it looks like GraphHopper Maps has a similar problem (I tried your
>     coordinates
>     <http://graphhopper.com/maps/?point=37.169792%2C25.449737&point=37.101957%2C25.375918>).
>     Currently the routing goes only from junction to junction and so
>     the second point resolves to the same junction. Will be fixed (in
>     the very near future) via #27
>
>     Not sure why there is a difference for the "two" areas. It would
>     be interesting for me to know where the second point resolves to
>     for your unexpanded area and how the route looks like (screenshot?).
>
>     Regards,
>     Peter.
>
>
>>     Following problem: I create a graphhopper app for one of the
>>     Greek Islands and it works. Now I expand the area to include
>>     other islands and the same app (no code changes) does not find
>>     the route (start and end point are the same as previously).
>>
>>     To me this suggests that once I include a wider area that is not
>>     connected to a subarea, it somehow confuses the routing. The
>>     exception is an IllegalArgumentException that says it cannot find
>>     point1 and cannot find point2 (then it also says the two are the
>>     same, I guess they are internally nulled after being unable to
>>     find them.).
>>
>>     The bounds for my OSM extraction are as follows:
>>
>>     #Naxos only: works
>>     export LEFT=25.3
>>     export RIGHT=25.7
>>     export TOP=37.3
>>     export BOTTOM=36.9
>>
>>     #Wider Aegais: does not work
>>     export LEFT=24
>>     export RIGHT=28.5
>>     export TOP=38
>>     export BOTTOM=35.2
>>
>>     # Slightly more verbose error message from the error stack:
>>     Error:[java.lang.IllegalArgumentException: Cannot find point 1:
>>     37.16979166666667, 25.449736666666663,
>>     java.lang.IllegalArgumentException: Cannot find point 2:
>>     37.101957, 25.375918, java.lang.IllegalArgumentException: Point 1
>>     is equal to point 2]
>>
>>     Any ideas why this is so?
>>
>>     Ludwig
>>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/graphhopper/attachments/20130923/522d02e4/attachment.html>