Thanks again Nate, I will take a look for sure. But just out of curiosity, what your ttc profile is useful for then? And how do you (in general, big picture only) define in a profile that it's subway only? And does it mean that when map matching against this profile, only subway routes will be returned? Patrick
2018-04-26 12:35 GMT-04:00 Nate Wessel <[email protected]>: > This one won't return a subway route because I haven't configured it for > that. I don't have subway trains in the dataset I'm working with for > Toronto. But it would be pretty easy to make a subway only profile, or to > add subways into this one if you want to do all transit modes in one > profile. Take a look at this page for documentation on how profiles work: > https://github.com/Project-OSRM/osrm-backend/blob/master/docs/profiles.md > > If you want to understand how map matching in OSRM works generally, I > think this paper is a good place to start: https://www.microsoft.com/en- > us/research/wp-content/uploads/2016/12/map-matching- > ACM-GIS-camera-ready.pdf > > When you change the profile, you're essentially configuring the > street/rail/whatever network that your GPS trace will match against. > Montreal definitely has subways in OSM; you can see them in the main map at > openstreetmap.org. > > Best, > Nate Wessel > Jack of all trades, Master of Geography, PhD Candidate in Urban Planning > SAUSy Lab <http://sausy.ca>, Sid Smith Hall, University of Toronto > > On 04/26/2018 10:52 AM, Patrick Agin wrote: > > Hi Nate and thank you very much for your help. I have a very basic > question about your ttc profile (sorry if it's too silly). When you match a > GPS dataset against this profile instance, will it return a subway route > for example? If yes, why this subway route would be declared much plausible > by osrm than the street route? Only because of the ttc profile? I realize > that I don't understand very well the involved mechanisms behind osrm and > profiles, if you can shed some light on this, I would greatly appreciate. > Another question: I suppose that the subway data has to be included in the > osm data of my city (Montreal) in order to get subway routes from match . > How can I know if it's there or not in my osm data? > Thank you again Nate, > Patrick > > 2018-04-26 9:36 GMT-04:00 Nate Wessel <[email protected]>: > >> I've had some success with transit matching by simply modifying the car >> profile to allow routing on streetcar tracks, allowing access for buses and >> public service vehicles, etc. Here's a profile I'm using for transit now: >> >> https://github.com/SAUSy-Lab/retro-gtfs/blob/master/etc/ttc.lua#L347 >> >> I had also tried to develop a more transit specific profile from the >> ground up. My thought was that known transit routes (provided in the OSM >> data) would be preferred by modifying their edge weights. This however ran >> into an issue with the matching service which hasn't been resolved yet; >> edge weights simply aren't used in match results. >> https://github.com/Project-OSRM/osrm-backend/issues/4785 >> >> If anyone has a suggestion for the question about multimodal paths, I >> would be very keen to hear it, however I suspect this is still an open >> topic of research with no definite best practices. >> >> Best, >> Nate Wessel >> Jack of all trades, Master of Geography, PhD Candidate in Urban Planning >> SAUSy Lab <http://sausy.ca>, Sid Smith Hall, University of Toronto >> >> On 04/26/2018 09:01 AM, Patrick Agin wrote: >> >> Dear all, >> >> I'm a newbie to routing engines and my first attempts are with OSRM. >> Specifically I want to use the *match *service. Questions I have is : >> >> 1) is it possible with match service to specify public transport (e.g. >> subway) as the mode of transportation? I see only profiles for car, bike >> and foot. If not, is there a solution? I'm pretty sure it it possible but >> how? I saw in some profiles the public_transport parameter but I don't know >> how to use it. >> >> 2) is it possible for match to return a multi-modal path given the >> timestamps of each coordinate? For example, return a sub-path that is the >> most plausible for pedestrian (chosen because of the low speed inferred >> from timestamps) followed by another subpath that is the most plausible for >> car (because of a higher speed)? Or is the only solution to pre-process the >> data to infer by myself the mode of transportation and make subsequent >> calls to the corresponding profile instance? >> >> Thanks a lot, >> >> Patrick >> >> >> _______________________________________________ >> OSRM-talk mailing >> [email protected]https://lists.openstreetmap.org/listinfo/osrm-talk >> >> >> >> _______________________________________________ >> OSRM-talk mailing list >> [email protected] >> https://lists.openstreetmap.org/listinfo/osrm-talk >> >> > > > _______________________________________________ > OSRM-talk mailing > [email protected]https://lists.openstreetmap.org/listinfo/osrm-talk > > > > _______________________________________________ > OSRM-talk mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/osrm-talk > >
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