[OSRM-talk] Eliminating, or reconstructing, via points

Richard Fairhurst richard at systemeD.net
Sun Jun 5 10:45:55 UTC 2016

Patrick Niklaus wrote:
> My solution for that would remove vias if the way through them is a
> shortest (duration) path. Technically shortest paths are not unique
> (think of grid cities). So this might lead to some route modifications
> that don't change the duration of the route but maybe the actual path.
> The way to implement this would be by doing a table query with the
> vias and removing via j from (i, j, k) if result.durations[i][j] +
> result.durations[j][k] == result.durations[i][k].
> For 2. the implementation would be pretty straight forward. Using the
> match plugin first obtain snapped via coordinates of the trace. Then
> apply 1. to minimize the via points.

Brilliant - thank you. Really good ideas and probably much simpler and 
faster than I'd have managed. :) I think the non-unique shortest path is 
unlikely to be an issue - most of the routes planned with cycle.travel 
are rural touring routes on winding roads, rather than in grid cities. 
Will have a go and report back!


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