Visualize overlapping routes

[dabreegster]

I'm interested in matching the GTFS route shapes to street network data, but not off-the-shelf valhalla/OSRM implementations necessarily. Collecting some notes...

• https://github.com/categulario/map_matching
• https://www.microsoft.com/en-us/research/wp-content/uploads/2016/12/map-matching-ACM-GIS-camera-ready.pdf
• https://blog.mapbox.com/matching-gps-traces-to-a-map-73730197d0e2
• https://www.youtube.com/watch?v=ChtumoDfZXI
• https://rosap.ntl.bts.gov/view/dot/38257

[dabreegster]

Actually the real problem I'm trying to solve here is in the GTFS network viewer. You can't click on red routes here, because usually there's a bunch of routes overlapping each other most of the time.

Inspiration: bottom of https://nbviewer.org/github/python-visualization/folium/blob/main/examples/plugin-PolyLineOffset.ipynb. I I already tried this idea out in another case, with max 4 paths: https://github.com/a-b-street/abstreet/pull/939

And I hacked together the same thing for GTFS routes. It looks... interesting. Has potential.

https://user-images.githubusercontent.com/1664407/179259991-d8457a38-850e-47dc-9425-60fa8babb352.mp4

To do this "for real", some things to figure out:

• can we do N-color theorem type stuff and mostly pick different colors? (There's one road that has 23 routes along it...)
• Adjust the road width hack and handle nearby roads smushing into each other, or at least fix the offset to center on the road
• Productionizing this quickly: for the bus_spotting import, manually provide an abstreet map model file
• The "proper" productionization: rely instead just on StreetNetwork. Add pathfinding there and lift the same map_gui overlapping paths logic to that.
• Actually snap the full route shape, not just the endpoints. (Or at least manually check the difference)

[dabreegster]

Sometimes working great, sometimes still getting "bowties" due to weird crossings like

[dabreegster]

References for how to do map matching: https://github.com/ad-freiburg/pfaedle