[OSRM-talk] MLD, Arc-based queries / multiple routings?

[Michael Krasnyk]

Hi Jens,

OSRM runs only one MLD search with one or two "phantom" arc nodes in the
source heap and  one or two arc nodes in the reverse heap ("phantom" nodes
are arcs with projected input locations and offsets for weights and
durations).
During the MLD search the query level of a node is computed as a minimum of
all possible up to 4 combinations of source and target phantom nodes in
getNodeQureyLevel function.

Starting on a cut edge is not different from starting on cell internal
edges because on the level 0 the overlay graph is not used.

Regards,
Michael

On Wed, May 3, 2017 at 1:46 PM, Jens Thiele <karme at karme.de> wrote:

> reading "Customizable Route Planning in Road Networks (2013)" [0]
> especially 4.2:
> "Arc-based Queries.
>
> In real-world applications, we often do not want to compute routes
> between intersections, but between points (addresses) along road
> segments. Hence, we define the input to our routing engine to be two
> arcs a_s and a_t with real-valued offsets o_s , o_t ∈ [0, 1]
> representing the exact start/end point along the arc.",
> I wonder how OSRM does handle this in the MLD case, especially when the
> points are on cut arcs.
>
> My first impression would be that one would have to run 4 MLDs to cover
> all possible directions?
>
> Greetings,
> Jens
>
> [0] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.721.8922
>
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