[OSRM-talk] Blocking zones in OSM

[Alex Valencia]

Hi Julien, Frederik.

  We really appreciate your comments. Are very useful guides to plan the
first steps of a potential POC.

  We will definitely report the findings we can get to help others with
similar issues and/or ask you for further guidance on this or other topics.
Thanks in advance.

  Alex Valencia



On Wed, Aug 26, 2020 at 4:34 AM Frederik Ramm <frederik at remote.org> wrote:

> Or, what Julien said ;)
>
> On 26.08.20 10:31, Frederik Ramm wrote:
> > Hi,
> >
> > On 26.08.20 03:29, Alex Valencia wrote:
> >>   So I was thinking if there is a proper way to achieve this goal. We
> >> are considering separating the matrix calculation over the map in a
> >> separate function and feeding it with a decorated version of the
> >> original map where we can remove these regions on the fly prior to the
> >> calculation. But I'm also not sure if this is a realistic way either.
> >
> > The only routing package I know that does polygonal avoid areas out of
> > the box is OpenRouteService which internally is powered by a modified
> > version of GraphHopper. However, only the simple route request supports
> > avoid areas, not the matrix request, and it's only available if you use
> > basic A*.
> >
> > Using avoid areas with Contraction Hierarchies is impossible unless the
> > avoid areas are baked into the graph (i.e. known at graph building
> > time). If your avoid areas *are* known at graph building time then
> > actually removing edges from the OSM data (or doing so while reading it
> > into OSRM) is certainly option that gives you the fastest routing speed.
> >
> > If you want to use OSRM, and if you want to use dynamic avoid areas,
> > then this *might* be possible with a MLD routing graph which has the
> > option of changing the weighting of certain edges without re-generating
> > the graph; this was implemented to allow for live traffic (search for
> > "osrm traffic" and you'll find some stuff about it, using
> > osrm-customize). However this still requires you to identify the edges
> > you wish to cut off (by giving them a zero rating), and it is only
> > possible globally and not on a per-request basis (unlike
> > OpenRouteService which lets you set avoid areas per-request).
> >
> > If you have a number of pre-defined avoid areas and want to determine
> > dynamically which of these should be avoided then it might be possible
> > to abuse a feature that was built to avoid certain road classes (i.e.
> > avoid motorways, avoid ferries); potentially you could use that to
> > define a specific road class for all roads in your avoid area A, a
> > different class for avoid area B etc., and then make a routing request
> > that "avoids class A". This feature is documented here
> > https://github.com/Project-OSRM/osrm-backend/issues/4006
> >
> > Bye
> > Frederik
> >
>
> --
> Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"
>
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