[GraphHopper] Looking for an engine for horse (and hiking) routing

[Peter K]

Hi Nop,

>> Ah, ok. Also putting parsing and storing the edges into two threads (+ a
>> queue) could speed things up.
>
> Yes, about 20-40% in my experience.

Today I could improve the CH preparation a lot and so the import process
of 4h (for world wide) is now significant and too long. So I would
appreciate every improvement and probably another issue should be created ;)


> CH seems to be pretty cool, but maybe a slower algorithm will do for
> my usecase. For horse routes, the distance will never be more than
> 50km, more realistically are 30km between start and destination.
yes, this would work well with a none-CH algorithm (on the server side).

> What is the second best algorithm in your experience?

If you mean an algorithm without preparation which are still exact, you
can try bidirectional dijkstra or astar. Bidirectional astar is not
really faster as the finish condition is not clear (to me).
And there are other algorithms with preparation which are fast but allow
more 'dynamical' behaviour than CH.


>> Nice, have fun :) ! I've also created this contributing file:
>> https://github.com/graphhopper/graphhopper/blob/master/CONTRIBUTING.md
>>
>> Let me know if you have questions!
>
> I do! The issue #46 is fixed in my fork. I even read your info and
> extended the oneWay test to cover it.
Nice!

> Actually, understanding the test was the hardest part. :-)
Which one? Reading a test should be easier :) !

>
> Unfortunately, 3 of the routing tests are failing now. I checked one
> of them, the input data contains several of the reverse oneways. So I
> believe that actually the test case was broken until now and the
> routing is got fixed.

Ah, ok. this could be indeed the case. But it is always a good feeling
to have a new feature already covered from the integration tests ;)
I could dig into it if you like.

>
> But as I never looked at routing and don't have any way to visualize
> or check those routing tests, I can't fix the test cases. I guess I
> need your help for that.

you can try the MiniGraphUI in the tools sub project (a raw desktop UI,
very good for visually debugging) or call
./graphhopper.sh web <osm file>
and then access localhost:8989


> Other than that I'd be ready to hand in the first fix. :-)

Feel free to create a pull request where we can further discuss this!
(ah, saw you already did it :) !)


> Oh, and I need help from you as list admin. I disabled the mails from
> the list to read at Nabble, but my posts from Nabble do not arrive at
> the list. Can you please reactivate the mails? I can't find the list
> settings, it only asks me to subscribe. :-(

I have just reactivated it - did this work for you?

Regards,
Peter.