[pgrouting-users] Regarding pgrouting and postgis for shortest path
Raghavan Krishnasamylakshmanaperumal
rkrish20 at uic.edu
Sat Jan 18 08:57:40 PST 2014
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> 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> 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>> 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>>> 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
>
--
Thanks and Regards,
Raghavan KL
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