Multiple waypoints in /route returns unwanted loops

[siljuovix]

Hi!

I am using OSRM built locally. When requesting a route using a pair of origin and destination coordinates like:

http://localhost:5000/route/v1/driving/13.203616,52.54085;13.203601,52.539946?annotations=true&overview=full&geometries=geojson&continue_straight=false

The response route coordinates are :

[13.203616, 52.54085],
[13.203616, 52.54085],
[13.20322, 52.540827],
[13.203056, 52.540802],
[13.20289, 52.540753],
[13.20277, 52.540709],
[13.202634, 52.540617],
[13.202552, 52.540476],
[13.20256, 52.540359],
[13.202597, 52.540204],
[13.20278, 52.540038],
[13.202893, 52.539996],
[13.202946, 52.539977],
[13.203113, 52.539934],
[13.20333, 52.539924],
[13.203601, 52.539946],
[13.203601, 52.539946]

On the map that looks like:

However, sending the request with those waypoints should return the same route:

http://localhost:5000/route/v1/driving/13.203616,52.54085;13.203616,52.54085;13.20322,52.540827;13.203056,52.540802;13.20289,52.540753;13.20277,52.540709;13.202634,52.540617;13.202552,52.540476;13.20256,52.540359;13.202597,52.540204;13.20278,52.540038;13.202893,52.539996;13.202946,52.539977;13.203113,52.539934;13.20333,52.539924;13.203601,52.539946;13.203601,52.539946?annotations=true&overview=full&geometries=geojson&continue_straight=false

The response route coordinates are :

[13.203616, 52.54085],
[13.203616, 52.54085],
[13.203616, 52.54085],
[13.20322, 52.540827],
[13.20322, 52.540827],
[13.203056, 52.540802],
[13.203056, 52.540802],
[13.20289, 52.540753],
[13.20289, 52.540753],
[13.20277, 52.540709],
[13.20277, 52.540709],
[13.202634, 52.540617],
[13.202634, 52.540617],
[13.202552, 52.540476],
[13.202552, 52.540476],
[13.20256, 52.540359],
[13.20256, 52.540359],
[13.202597, 52.540204],
[13.202597, 52.540204],
[13.202503, 52.540099],
[13.202484, 52.540079],
[13.202443, 52.540033],
[13.202421, 52.540011],
[13.202294, 52.539917],
[13.201958, 52.539711],
[13.202135, 52.539585],
[13.202437, 52.539728],
[13.202731, 52.53982],
[13.202795, 52.539841],
[13.202928, 52.539881],
[13.203113, 52.539934],
[13.20333, 52.539924],
[13.203601, 52.539946],
[13.203855, 52.540011],
[13.204069, 52.540161],
[13.204154, 52.540286],
[13.20416, 52.54042],
[13.204042, 52.540593],
[13.203922, 52.540713],
[13.203814, 52.540771],
[13.203616, 52.54085],
[13.20322, 52.540827],
[13.203056, 52.540802],
[13.20289, 52.540753],
[13.20277, 52.540709],
[13.202634, 52.540617],
[13.202552, 52.540476],
[13.20256, 52.540359],
[13.202597, 52.540204],
[13.20278, 52.540038],
[13.20278, 52.540038],
[13.202893, 52.539996],
[13.202893, 52.539996],
[13.202946, 52.539977],
[13.202946, 52.539977],
[13.203113, 52.539934],
[13.20333, 52.539924],
[13.203601, 52.539946],
[13.203855, 52.540011],
[13.204069, 52.540161],
[13.204154, 52.540286],
[13.20416, 52.54042],
[13.204042, 52.540593],
[13.203922, 52.540713],
[13.203814, 52.540771],
[13.203616, 52.54085],
[13.20322, 52.540827],
[13.203056, 52.540802],
[13.20289, 52.540753],
[13.20277, 52.540709],
[13.202634, 52.540617],
[13.202552, 52.540476],
[13.20256, 52.540359],
[13.202597, 52.540204],
[13.202503, 52.540099],
[13.202484, 52.540079],
[13.202443, 52.540033],
[13.202421, 52.540011],
[13.202294, 52.539917],
[13.201958, 52.539711],
[13.202135, 52.539585],
[13.202437, 52.539728],
[13.202731, 52.53982],
[13.202795, 52.539841],
[13.202928, 52.539881],
[13.203113, 52.539934],
[13.203113, 52.539934],
[13.20333, 52.539924],
[13.20333, 52.539924],
[13.203601, 52.539946],
[13.203601, 52.539946],
[13.203601, 52.539946]

I am aware there are similar reports of the same behaviour, but setting continue_straight=false does not avoid the route to be extended like in the figure.

Perhaps someone can help me understanding the reason for this results?

Thank you!

[danpat]

When you pass in a coordinate that is exactly at an intersection, it's a bit of a crapshoot whether it'll snap to the edge before or after the intersection.

If there are oneways involved, this can force the route to take a big detour.

An explanation and suggest path to addressing this is described in #4465

You can avoid this by using the /match service instead of /route - /match will try several nearby candidate snapping points, and should resolve the issue for you.

[siljuovix]

@danpat I understand now. Thank you so much!