Routing from exact node location

[ZsoltMedgyesi-Itineris]

The problem is , when i try routing from a position, which is an exact location of an intersection node, not all the ways from that node are taken into account (in the example case, the link).

Like such:

Notes:

• The green arrow marks the prefered outcome.
• Black line is the actual outcome (does a turn-around , when its possible, several km-s away).
• I tried with both routability and duration weight settings, same outcome
• The profile is based on car.lua
• Multiple alternatives are turned on, but it does not produce the prefered outcome.
• All the turn-restrictions and one-ways are checked

[oxidase]

@ZsoltMedgyesi-Itineris OSRM uses the nearest OSM way segment to the input location as a starting point of the route. If the input location is exactly at an intersection node and distances from the input point to ways segments are 0 then the first allowed segment in will be used. The order of segments is fixed during generation of the R-tree for segments lookup and can not be changed at the query phase.

A possible solution can be in adding a small delta to the input coordinate in the required direction.

[ZsoltMedgyesi-Itineris]

@oxidase Thanks for the clarification. The problem is, that in the given application waypoints can be 1-10 minutes apart. Which means the direction of the delta in the required way cannot be defined reliably. Trying in multiple directions probably would be a solution, but not an elegant/efficient one.

May you have any other suggestion, or should we close this issue?

[oxidase]

@ZsoltMedgyesi-Itineris sorry, i don't know other "easy" solution without OSRM modifications. The correct fix would be to use multiple source/target nodes that have the same distances to the input location that sounds like an easy fix, but the devil is in the detail:

• NearestPhantomNodeWithAlternativeFromBigComponent functions must be adjusted to return std::pair<std::vector<PhantomNode>, std::vector<PhantomNode>>.

• GetPhantomNodes must return std::vector<std::vector<PhantomNode>>, also the check that all phantom nodes are in the same component must be adjusted.

• insertNodesInHeaps must be adjusted to insert multiple source and target phantom nodes.

• getNodeQueryLevel functions also will need an adjustment.

So almost all parts of osrm::engine that are related to the initialization of routing plugins must be modified.

The current issue duplicates #2167, but the previous issue was about synthetic feature tests and the current one presents a real use case.

So I think it is ok to keep it open and close #2167 instead.

[danpat]

Also related is #4465, where the fix is basically the same.

[github-actions]

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