[postgis-users] Road Network Graph creation

[Jaak Laineste]

Hi Daniel,

Yes, I am aware about this tool. However, it has couple of limits:
 - I need to build and install it. I'm not big fan of this.
 - Data size - I'd like to use it with bigger datasets. Anyway, then I'd
expect good performance of pgrouting also with big datasets (like
pan-European/global OSM within 1 second). Maybe this is not too realistic,
SQL-based routing cannot be expected to be so well optimized than
specialized binary in-memory solutions.
 - source of data. Some of my datasets are not OSM-based.

Actually my approach is a bit dangerous. When I cut lines from all
intersections I get too sometimes too many nodes, as I assume there that the
street network has specific topology: no multi-level crossings.  In some
less dense areas (countryside without motorways) this assumption is more or
less ok, and for basic demos it should be ok; but not for big datasets it
creates errors. 

 My current workaround was to use ArcGIS Desktop, this has function
"Planarize" which did exactly what I needed, with very good performance
(http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Making_new_fe
atures_with_topology_tools). This is quite expensive solution, but I could
not find and free GIS tool to do same.

One scalable solution would be to have OSM 2 pgrouting converter written in
Postgres SQL, taking data directly from OSM "simple" DB schema. Then it only
assumes that I have simple schema and routing schema in the same DB, or at
least connected via DB link. It would give also good flexibility for users,
as you do not need to know C to make small adaptations.

/Jaak


> Hi Jaak,
> 
> If you need to get the network graph of OSM data you can use
> osm2pgrouting:
> http://pgrouting.postlbs.org/wiki/tools/osm2pgrouting
> 
> Currently it doesn't work with large amount of data.
> Contributions are always welcome ;-)
> 
> Daniel
> 
> 
> Jaak Laineste schrieb:
> >
> > Hi,
> >
> >  This function assumes that the road network is already segmented. If
> > I have otherwise topologically good network, but without properly
> > segmented streets (e.g. like in OSM Shapefiles), then it does not
> work.
> >
> >
> >
> >  Best solution would be to have similar extended postgis or pgrouting
> > function to do it. Or is there any other good (and free) tool to do
> it?
> >
> >
> >
> > /Jaak
> >
> >
> >
> >
> >
> > Re: [postgis-users] Road Network Graph creation
> >
> > Daniel Kastl
> > Sun, 28 Jun 2009 17:17:33 -0700
> >
> >
> >
> > You need to look for the assign_vertex_id function of pgRouting.
> > This function creates a network topology.
> >
> > Daniel
> >
> >
> > Ben Madin schrieb:
> >
> > Short Answer - Yes - but of course it depends on the quality of your
> > shapefile as to how useful it is.
> >
> >
> > Have a look at : http://pgrouting.postlbs.org/
> >
> > cheers
> >
> > Ben
> >
> >
> >
> >
> > On 28/06/2009, at 11:09 PM, Sandeep Kumar Jakkaraju wrote:
> >
> > Hello All
> >
> >
> > Is there any way I can create a road network graph (nodes,edges) from
> > a road shapefile ?
> >
> > --
> > Thanks
> > Regards
> >
> > Sandeep Kumar Jakkaraju
> >
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> >
> >
> >