[pgrouting-users] "pgr_nodeNetwork" function is not working properly

[Stephen Woodbridge]

This is a known problem and it has a pull request if you want to check 
it out:

https://github.com/pgRouting/pgrouting/issues/280
https://github.com/pgRouting/pgrouting/pull/282

-Steve

On 3/16/2015 12:41 PM, Candan Eylül Kilsedar wrote:
> ​​Hi everyone,
>
> I am using pgrouting on OpenStreetMap data and I want to node the
> network using the function "pgr_nodeNetwork function", however the nodes
> are not created correctly. I am importing a large set of data
> to PostgreSQL in the following way:
>
>
> BBOX="8.944,45.830, 9.441,46.323"
> wget --progress=dot:mega -O "roads_osm_viaregina.osm"
> "http://www.overpass-api.de/api/xapi?*[bbox=${BBOX}][@meta]"
>
> osm2pgrouting -file "/home/kilsedar/Desktop/DATA/roads_osm_viaregina.osm" \
>                            -conf "/usr/share/osm2pgrouting/mapconfig.xml" \
>                            -dbname pgrouting-viaregina \
>                            -user postgres \
>    -host localhost \
>                            -clean
>
>
>
> At this point, if analyze the graph using pgr_analyzeGraph function by
> "/SELECT pgr_analyzegraph('ways', 0.001, 'the_geom', 'gid');/" the
> result I am getting is the following:
>
> NOTICE:              ANALYSIS RESULTS FOR SELECTED EDGES:
> NOTICE:                    Isolated segments: 86
> NOTICE:                            Dead ends: 8172
> NOTICE:  Potential gaps found near dead ends: 7419
> NOTICE:               Intersections detected: *1159*
> NOTICE:                      Ring geometries: 12
>
>
>
> Later if I run
>
> /"SELECT pgr_nodeNetwork('ways', 0.001, 'gid', 'the_geom');"/
>
> /"SELECT pgr_createTopology(ways_noded, 0.001);"/
>
> /"SELECT pgr_analyzegraph(ways_noded, 0.001//)//;"/
>
> I get the following result:
>
> NOTICE:              ANALYSIS RESULTS FOR SELECTED EDGES:
> NOTICE:                    Isolated segments: 5
> NOTICE:                            Dead ends: 958
> NOTICE:  Potential gaps found near dead ends: 329
> NOTICE:               Intersections detected: *5173*
> NOTICE:                      Ring geometries: 12
>
>
> As you can see, the number of intersections increased, instead of
> descreasing.
>
>
> NOTE: Somehow, by playing with the tolerance parameter and setting it to
> "0.000045" I decreased the number of intersections to 957, and the
> complete result is the following:
>
> NOTICE:              ANALYSIS RESULTS FOR SELECTED EDGES:
> NOTICE:                    Isolated segments: 58
> NOTICE:                            Dead ends: 7851
> NOTICE:  Potential gaps found near dead ends: 68
> NOTICE:               Intersections detected: 957
> NOTICE:                      Ring geometries: 12
>
>
>
> In the attachment, I am sending a screenshot of the same data in QGIS,
> where the bounding box is "9.265,46.108, 9.276,46.118" and the tolerance
> parameter is "0.001". In this screenshot you can see that in some
> intersections, nodes are not created. It is trivial to see that red
> nodes are the ones that are created after noding.
>
>
> Is it possible to identify the problem, or if the function is running
> correctly?
>
>
> Thank you,
>
>
> Regards,
>
>
> Candan Eylul Kilsedar
>
>
>
>
>
>
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