[OSRM-talk] OSRM match service for public transportation

Thu Apr 26 20:00:31 UTC 2018

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 <nate.wessel at mail.utoronto.ca>:

> 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 <nate.wessel at mail.utoronto.ca>:
>
>> 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 <nate.wessel at mail.utoronto.ca>:
>>
>>> 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
>>>
>>>
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