[OSRM-talk] Some OSRM Match questions

Artur Bialecki abialecki at intellimec.com
Wed Nov 11 18:51:44 UTC 2015


I'm not sure how --max-matching-size works. I'm running osrm-routed  (v4.8.1) without any options and I’m successfully matching a trip with 815 locations.

Artur...

-----Original Message-----
From: Paul Friedman [mailto:paul.friedman at streetlightdata.com]
Sent: Wednesday, November 11, 2015 1:29 PM
To: osrm-talk at openstreetmap.org
Subject: Re: [OSRM-talk] Some OSRM Match questions

Sorry, wrong subject line.  Reposting to link the thread.

I'm also starting to use this API (and completely love the results).

It appears the default for –max-matching-size is 2.  Is there a reason the limit is so low (or is it even enforced?)?  Thanks.

---Paul

-----Original Message-----
Date: Wed, 11 Nov 2015 00:07:32 +0100
From: Patrick Niklaus <patrick.niklaus at student.kit.edu>
To: Mailing list to discuss Project OSRM <osrm-talk at openstreetmap.org>
Subject: Re: [OSRM-talk] Some OSRM Match questions
Message-ID:
        <CAFxP+1Pgb_2bx2r=Tahsu0D4W+YurWKpxE33oM6RMZWi=F_C+A at mail.gmail.com>
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> Which is the recommended way?

Increase the locations limit. Stitching together split traces might not yield the expected result (start/end points at the split don't have to match). In general the more data you provide, the better the algorithm is able to work.

> Are the timestamps used as part of the Hidden-Markov-Model algorithm?

They don't influence the emission probabilities or transition probabilities, but are used for detecting outliers and gaps (simple example is driving through a tunnel). You should provide the data if you have it.

> In my response to a match query I’m getting hint_data.

You can use hint_data as additional input to viaroute. It enables unambiguous coordinate snapping (important if you want to match first and then extract additional information). As with viaroute it cannot be turned off (also adds no real overhead anyway).



On Tue, Nov 10, 2015 at 10:01 PM, Artur Bialecki <abialecki at intellimec.com>
wrote:
>
>
> Hello,
>
>
>
> I’m new to OSRM and I have few question regarding the map matching API.
>
> I’m using version v4.8.1.
>
>
>
> If I have a trip with 1000 locations, what are the implications of
> setting
>
> –max-matching-size option of osrm-routed as oppose to splitting the
> trip
>
> into 10 requests with 100 locations each and stitching together the
> responses?
>
> Which is the recommended way?
>
>
>
> The match API takes locations and optional timestamps for each location.
>
> Are the timestamps used as part of the Hidden-Markov-Model algorithm?
>
> Is the match quality or performance affected when using the timestamps?
>
>
>
> In my response to a match query I’m getting hint_data.
>
> The API documentation does not mention this. Is hint_data usable for
> match
>
> requests? If so how? If not, now do I turn it off?
>
>
>
> Is there a way to turn off logging of requests by osrm-routed, other
> than sending them to /dev/null?
>
>
>
> Is there any documentation on using profile.lua?
>
>
>
> Thank you.
>
>
>
> Artur Bialecki.
>
>
>
>
>
>
>
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