[pgrouting-users] Regarding pgrouting and postgis for shortest path
Raghavan Krishnasamylakshmanaperumal
rkrish20 at uic.edu
Thu Jan 16 14:56:33 PST 2014
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
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