[pgrouting-users] Shortest Route Search Not Working

Yasir Shoaib yasirshoa at gmail.com
Sun Jul 18 01:10:50 EDT 2010


Hello Dan,

Sure, you can send me the data as well.

Thanks,
Yasir

>* Hi Daniel,
*>*
*>* To follow on Yasir's comments in terms of routing results, I've been
*>* working with a simple example data set where the distance and travel time
*>* results are likely to be different (really there are several equally good
*>* routes based on distance, but a unique route based on travel time, but with
*>* the "length" field in the database reflecting travel time along an edge).
*>* When doing the routing based on travel time I get the correct solution using
*>* the Dijkstra algorithm, but an incorrect result using the A* and Shooting
*>* Star algorithms. The nature of the errors I'm getting would be consistent
*>* with what Yasir is finding. I'd be glad to send you both the network data
*>* and my test queries. I'm running on 64bit Ubuntu 10.04 using the Ubuntu
*>* repository version of PostgreSQL (8.4.4), PostGIS 1.5.1, and built pgRouting
*>* from the subversion repository on Tuesday.
*>*
*>* Dan
*>*
*>* --- On Fri, 7/16/10, Daniel Kastl <daniel.kastl at georepublic.de
<http://lists.osgeo.org/mailman/listinfo/pgrouting-users>> wrote:
*>*
*>* From: Daniel Kastl <daniel.kastl at georepublic.de
<http://lists.osgeo.org/mailman/listinfo/pgrouting-users>>
*>* Subject: Re: [pgrouting-users] Shortest Route Search Not Working
*>* To: pgrouting-users at lists.osgeo.org
<http://lists.osgeo.org/mailman/listinfo/pgrouting-users>
*>* Received: Friday, July 16, 2010, 9:58 PM
*>*
*>*  I hope you don't mind helping me with another couple short questions:
*>* 1. Projection 4326 with latlng is lot easier for me to work with. Although
*>* there are ways to convert the latlng to
*>*  900913 projection, I was wondering how would I be able to directly use
*>* 4326 and run search on it (HTML changes), assuming that the tiles were
*>* generated with 900913 projection and the routing database is set to 4326?
*>*
*>*
*>*
*>* You can use Postgis "transform()" function to do this:
*>* http://postgis.refractions.net/docs/ST_Transform.html
*>*
*>*
*>*
*>* 2. Just out of curiosity.
*>* The routing results usually take residential route ways, instead of taking
*>* instead of taking highway streets (which is more like what results from
*>* Google Maps show). Any ideas why the difference?
*>*
*>*
*>*
*>* pgRouting gives you the "shortest" path and it's up to you to define what
*>* is "shortest". Easiest is to take length as cost, but if you take time as
*>* cost, then shortest will be the fastest. You could for example define some
*>* speed for your road classes, and if the speed is higher on highways it will
*>* prefer the highway like Google Maps does.
*>*
*>*
*>* Daniel
*>*
*>*
*>* Thanks
*>*
*>*
*>* _______________________________________________
*>*
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*>* http://lists.osgeo.org/mailman/listinfo/pgrouting-users
*>*
*>*
*>*
*>*
*>*
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