[pgrouting-users] Facing issue on node creation

Stephen Woodbridge woodbri at swoodbridge.com
Mon Apr 21 13:05:22 PDT 2014

Hi Raghavan,

pgr_nodeNetwork is not intended for this purpose. It assumes you have a 
series of street segments that might not be noded correctly and then 
chops them into smaller segments that are noded where they cross one 

We do not have tools for building well structured street networks from 
multiple GPS tracks. You have to convert the tracks to streets before 
coming to pgRouting. Look at postGIS or OSM as they have tools that are 
more appropriate to this task.


On 4/21/2014 3:51 PM, Raghavan Krishnasamylakshmanaperumal wrote:
> Hi All,
> I am using pgr_nodeNetwork with threshold 0.00001 to create nodes and
> pgr_createTopology with a threshold of 0.0001 on the GPS traces which I
> have collected. The resultant graph from this data looks weird due to
> the creation of nodes so close to each other as I have visualized in the
> attached pictures. The black circles are the nodes and you could see
> that they are created such a way they are overlapping densely. I thought
> using pgr_nodeNetwork threshold could solve this issue but it did not
> help me in this case.
> If I increase the threshold above 0.00001, I get the following error
>     psql:run_pgr_node_network.sql:1: ERROR:  getPoint4d_p: point offset
>     out of range
>     CONTEXT:  SQL statement "create temp table inter_loc on commit drop
>     as ( select * from (
>              (select l1id, l2id, st_linelocatepoint(line,source) as
>     locus from intergeom)
>               union
>              (select l1id, l2id, st_linelocatepoint(line,target) as
>     locus from intergeom)) as foo
>              where locus<>0 and locus<>1)"
>     PL/pgSQL function pgr_nodenetwork(text,double
>     precision,text,text,text) line 184 at EXECUTE statement
> So the graph formed out of my GPS traces is so noisy and not able to use
> it for any of my experiments. Please suggest if I can use any other
> function or approach to make my graph with more cleaner structure.
> --
> Thanks,
> Raghavan KL
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