And by "handle subway lines", you mean "specify that only subway edges are included"? Can I ask you to point in .lua profile where you specify such a thing? In restricted_highway_whitelist structure maybe? The readme on profiles seems good but it's general (for example, there is nothing about this restricted_highway_whitelist). Do you know where can I find a complete tutorial/documentation on writing profiles? thanks again Nate Patrick
2018-04-26 15:30 GMT-04:00 Nate Wessel <[email protected]>: > You can use a profile to determine which edges are included in the graph, > which are accessible, etc. If for example you only handled subway lines in > the profile and disregarded all other data from OSM, you would only be able > to match things to subways. > > A GPS trace from someone e.g. walking aboveground but parallel to a subway > track would also likely match to the subway rails because there would be no > more-likely candidates to match to. > 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 02:32 PM, Patrick Agin wrote: > > 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-u >> s/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 >> >> > > > _______________________________________________ > 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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