[OSRM-talk] new api table and geometry

[Michal Palenik]

i've added a feature request
https://github.com/Project-OSRM/osrm-backend/issues/2519



the unpacking of edges phase should allow for impedance vs. speed debate
to move, also allowing for elevation to be stored in osrm.
i've tried to say this in my last comment at
https://github.com/Project-OSRM/osrm-backend/issues/77


michal
On Fri, Apr 15, 2016 at 10:27:40PM +0200, Michal Palenik wrote:
> daniel, 
> 
> thanks for the explanations.
> 
> my need to calculate (and show) only 1x15 matrix blurred my vision of
> all the problems :)
> 
> what I try to achieve is multimodal routing (foot+bus+foot) by showing
> three geometries combined into one (plus some instructions).
> 
> michal
> 
> On Fri, Apr 15, 2016 at 12:56:20PM -0700, Daniel Patterson wrote:
> > Michal,
> > 
> >   Strangely enough, we don't actually have the geometry.  We find a path across the Contraction Heirachy
> >   routing graph, this may only have a small handful of edges.  We can sum these edges to get the route
> >   duration, but to get the actual geometry or distance, we then have to "unpack" those edges.
> > 
> >   The table plugin doesn't do this unpacking step.  It gets the durations easily, but would be significantly slower
> >   if we also had to report back the route geometries.  The API response would probably also be huge (10s or 100's of MB?) for any
> >   non-trivial number of route pairs in the table.  To support that, we would need a way to stream the response
> >   asynchronously to the HTTP client, otherwise a couple of requests could use up all the RAM on the server.
> > 
> >   Things are never as simple as they seem :-(
> > 
> > daniel
> > 
> > > On Apr 15, 2016, at 12:45 PM, Michal Palenik <michal.palenik at freemap.sk> wrote:
> > > 
> > > that is what I already do, but it means a lot of (unnecessary)
> > > connections. I assume the geometries are already available when
> > > computing the duration. 
> > > 
> > > I was hoping for a "documentation lacking behind development"
> > > scenario... 
> > > 
> > > 
> > > cheers, 
> > > michal
> > > 
> > > On Fri, Apr 15, 2016 at 04:09:49PM +0200, Daniel Hofmann wrote:
> > >> If you check the v5 spec you linked, you will see only Route, Trip and
> > >> Match providing a "geometries" option.
> > >> 
> > >> What you can do is this:
> > >> - do a Table request from your position against all Bus / Tram stops in the
> > >> area / in a buffer of a few kilometers
> > >> - pick n shortest routes from the Table response and temporarily store
> > >> their destination coordinates
> > >> - do n Route request from your position against the n destination
> > >> coordinates and extract the geometry
> > >> 
> > >> Cheers,
> > >> Daniel J H
> > >> 
> > >> On Fri, Apr 15, 2016 at 3:49 PM, Michal Palenik <michal.palenik at freemap.sk>
> > >> wrote:
> > >> 
> > >>> hi,
> > >>> 
> > >>> within the new api, I am trying to find how to get geometry (together
> > >>> with perfect duration). is it possible?
> > >>> 
> > >>> or do I have to make N*M queries for all the possible combinations?
> > >>> 
> > >>> 
> > >>> https://github.com/Project-OSRM/osrm-backend/wiki/New-Server-api#service-table
> > >>> 
> > >>> I am trying to make a service like "show me the routes to the closest
> > >>> bus/tram stops" : http://epsilon.sk/mhd/
> > >>> 
> > >>> thanks
> > >>> 
> > >>> michal
> > >>> 
> > >>> --
> > >>> michal palenik
> > >>> www.freemap.sk
> > >>> www.oma.sk
> > >>> 
> > >>> 
> > >>> _______________________________________________
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> > >>> 
> > > 
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> > > 
> > > -- 
> > > michal palenik
> > > www.freemap.sk
> > > www.oma.sk
> > > 
> > > 
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> > 
> > 
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> 
> -- 
> michal palenik
> www.freemap.sk
> www.oma.sk
> 
> 
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-- 
michal palenik
www.freemap.sk
www.oma.sk