[pgrouting-users] Regarding pgrouting and postgis for shortest path
Stephen Woodbridge
woodbri at swoodbridge.com
Sat Jan 18 11:10:18 PST 2014
Raghavan,
Great! Glad I could help and that you were able to get things going.
-Steve
On 1/18/2014 11:57 AM, Raghavan Krishnasamylakshmanaperumal wrote:
> Steve,
>
> I followed your instructions and it worked like a magic. Thanks for
> helping me with this task.
>
> Thanks,
> Raghavan
>
>
> On Thu, Jan 16, 2014 at 4:56 PM, Raghavan Krishnasamylakshmanaperumal
> <rkrish20 at uic.edu <mailto:rkrish20 at uic.edu>> wrote:
>
> Steve,
> Sure I will try following the above mentioned steps. Hope this will
> guide me to further proceed in my work.
> Thanks for sharing your knowledge.
>
> Thanks,
> Raghavan
>
>
> On Thu, Jan 16, 2014 at 4:11 PM, Stephen Woodbridge
> <woodbri at swoodbridge.com <mailto:woodbri at swoodbridge.com>> wrote:
>
> On 1/16/2014 4:54 PM, Raghavan Krishnasamylakshmanaperumal wrote:
>
> Steve,
>
> Thanks for pointing out various resources, probably I didn't
> explain
> about my data properly. So the data which I have is not just
> two points,
> I have collected data from my and some of my friend's runkeeper
> <http://runkeeper.com/> GPS traces for various activities
> like running,
>
> walking, biking in and around Chicago. I have all these GPS
> points(longitude,latitude) information with me. What I am
> trying to find
> is the shortest path given any two points from the data
> which I have
> collected.
>
>
> Then you should be able to:
> 1. load the track points into a table
> 2. convert the tracks into linestrings
> 3. then run pgr_nodenetwork
> 4. update the resulting table to include costs or lengths
> 5. then run pgr_createTopology
> 6. then map a start point and end point to the network nodes
> 7. call pgr_dijkstra to get shortest path
>
> All of the above happens in the database
>
> 8. write a client application the connects to the database maps
> the start and end points, computes the path and displays it or
> whatever you need to do with it.
>
> -Steve
>
> Thanks,
> Raghavan
>
>
> On Thu, Jan 16, 2014 at 3:42 PM, Stephen Woodbridge
> <woodbri at swoodbridge.com <mailto:woodbri at swoodbridge.com>
> <mailto:woodbri at swoodbridge.__com
> <mailto:woodbri at swoodbridge.com>>> wrote:
>
> On 1/16/2014 4:31 PM, Raghavan
> Krishnasamylakshmanaperumal wrote:
>
> Steve,
> Thanks for your reply, I think I almost understood.
> So you say that
> having only these GPS point may not help me I
> should also have the
> network map corresponding to these GPS points using
> which I can
> figure
> out the shortest path?
>
>
> if you only have two point on the earth and nothing
> more what is the
> shortest path. "Path" implies that you have a network
> of paths and
> that you want to find the the shortest path within the
> network. If
> you only have the points and no network then you can
> not find the
> shorth path in the network, because you do not have one.
>
> The way things works is that we take a point and find
> the nearest
> edge ot node in our network for that point and that
> then becomes the
> start or end point in the network. Dijkstra then
> searchs the network
> for the shortest path between two points.
>
>
> So right now I have only these GPS points, how
> should I proceed
> further
> to figure out the shortest path between any two GPS
> points from
> my data.
>
>
> You can't do anything with just these points. You have
> to make them
> to a network and then search for a solution within that
> network.
>
> So you have to find network data that you can use for
> your area of
> interest. You might look at OSM data and osm2pgrouting
> to load it
> into pgRouting.
>
> You could also look into using Project-OSRM (requires
> 64bit HW)
> which is the router used by OSM.
>
>
> I am open to use any database/framework/language so
> please
> suggest me
> how to proceed further and I am concerned about
> scalability or
> other
> factors because this is just a proof of
> concept(course project)
> which I
> am trying to build.
>
>
> pgRouting
> Project-OSRM
> google: java dijkstra
>
> There are lots of choices, but all require that you
> have network data.
>
> -Steve
>
> Thanks,
> Raghavan
>
>
> On Thu, Jan 16, 2014 at 12:21 PM, Stephen Woodbridge
> <woodbri at swoodbridge.com
> <mailto:woodbri at swoodbridge.com>
> <mailto:woodbri at swoodbridge.__com
> <mailto:woodbri at swoodbridge.com>>
> <mailto:woodbri at swoodbridge.
> <mailto:woodbri at swoodbridge.>____com
>
> <mailto:woodbri at swoodbridge.__com
> <mailto:woodbri at swoodbridge.com>>>> wrote:
>
> On 1/16/2014 12:46 PM, Raghavan
> Krishnasamylakshmanaperumal
> wrote:
>
> Recently I started using PostGIS for my
> academic
> project which is a
> route recommendation system. I have stored
> the data in the
> following format.
> /
> /
> /gid=>integer, activity=>varchar(20), geom
> geometry(Point,4326)/
>
>
> geometry points are longitude and latitude
> information, for
> example if
> you record your Running activity using a
> gps device,
> each point
> record
> (longitude & latitude) is stored in the
> geom column.
>
>
> The shortest distance between two points is a
> straight line
> unless
> you want to constrain the problem to the
> shortest distance
> along
> some road or path network.
>
> If it is constrained to a networks of paths
> then you have
> to have
> the data for that network available.
>
> In the case of pgRouting, you have to load the
> network data and
> prepare it for routing, then you can use you
> points as the
> start and
> end points of a route and ask pgRouting to
> fins the
> shortest path
> between them along the network.
>
>
> I need to find the shortest path(using
> Dijkistra's)
> between any
> two geom
> points from this data set and I am trying
> to automate
> this using
> some
> programming language like Java.
>
>
> With Java you can connect to the database and
> issue simple
> queries
> to pgRouting to get your results. If you are
> looking for a Java
> library to solve Dijkstra problems then this
> is not
> pgRouting. Also
> if you are using a Java library you will still
> need to load the
> network of paths that you want to solve you
> queries against.
>
> Hope this helps,
> -Steve
>
> Please can you suggest me how to make use
> of pgrouting and
> postgis data
> to figure out the shortest path. Is there
> any library
> available to
> automate this using Java. I am totally
> stuck on my
> project and
> finally
> came to know about this mailing list.
>
>
> --
> Thanks and Regards,
> Raghavan KL
>
>
>
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> --
> Thanks and Regards,
> Raghavan KL
>
>
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> --
> Thanks and Regards,
> Raghavan KL
>
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> Thanks and Regards,
> Raghavan KL
>
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> --
> Thanks and Regards,
> Raghavan KL
>
>
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