[GraphHopper] turn restrictions

[Bruno Carle]

Hi Peter, we split the request containing via points into simple point to
point request using our own model objects, not directly using GH api, so it
can not be reused directly. But if you wish I can send the classes involved.
Bruno


On Fri, Aug 22, 2014 at 12:28 PM, Peter <graphhopper at gmx.de> wrote:

>  ah, yes. If there is a one-way network around the restriction a failed
> route for '1dir' is a lot more likely. So maybe we remove this option
> entirely as it now does not look that good anymore for me in real world.
>
> The best thing would be if we could create a hybrid solution. Doing '1dir'
> for areas with no restrictions and '2dir' for the other areas which are a
> lot less likely. This way we would have same speed as node-based traversal
> but with correct routes. There is a paper for this hybrid but we probably
> have to keep it simple for now ...
>
>
> > For our own usage I think we would not use EDGE_BASED_2DIR_UTURN
> because, the u turn are mainly for the via points
>
> I also do not like the routes it produces and also forbidden u-turns are
> not that often tagged and so it produces forbidden routes. So yes, maybe we
> remove this option also and instead make an u-turn option available for the
> via-points. If you have some code for this please do not hesitate to
> contribute :)
>
> Regards,
> Peter.
>
>
> On 22.08.2014 09:57, Bruno Carle wrote:
>
> Hi Peter,
> In the namesti miru example the path will not be found, even using the
> full city map, this is because the northest part of the Varsavska street is
> only accessible thru easter part of Uruguaska,
> which is in only accessible from Francouska driving south/east. For the
> map see
> https://graphhopper.com/maps/?point=50.074831%2C14.439039&point=50.07333%2C14.43869
> and http://imgur.com/MftaocZ
>
>
> I will run later against a batch of usage routes from our prod and let you
> know how often it happens.
>
> Regarding u turn, 0-1-2-1-6 would not be allowed in this namesti miru
> example (the node 2 beeing where Francouska  joins Namesti Miru),
> For our own usage I think we would not use EDGE_BASED_2DIR_UTURN because,
> the u turn are mainly for the via points (i.e. after picking/dropping a
> delivery), and we do not use GH' via points, instead we perform several
> point to point requests,
> so u turns in this case are automatically covered by the query graph.
>
> My feeling is that  often  EDGE_BASED_2DIR_UTURN, will produce routes with
> u turns which are not allowed.  Again I will run against some batch and let
> you know how often it happens.
>
> Regards
> Bruno
>
>
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