[pgrouting-users] Wierd results using pgr_kdijkstraPath
Daniel Kastl
daniel at georepublic.de
Thu Dec 18 23:43:11 PST 2014
Hi Eyad,
Looking at just a few of your network images, the network is definitely
broken afterwards. So it's not the fault of the shortest path algorithm.
Without access to the data I can only guess, but often CAD data may contain
geomtries, that don't work well for GIS.
When I look at some screenshots and which parts have been removed, could it
be, that your data contains circles or self-intersecting linestrings for
example?
Daniel
On Fri, Dec 19, 2014 at 4:16 PM, AUS - Eyad <b00038807 at aus.edu> wrote:
>
> Thanks Steve..
>
> It seems that I may need to re-install the pgRouting to update the
> "ST_DumpPoints()"?
>
> Can I split the lines on CAD instead? Then pgr_nodeNetwork() adds nodes
> correctly? Or I may get to same situation if the bug is in the nodding, not
> in splitting lines?
>
> I have done a cross-check for the pgr_kdijkstraCost and pgr_kdijkstraPath
> results. The cost results are exactly the same. But I'm still not sure if
> the calculated cost is done based on the real shortest_path because I can't
> see the outcome on the map
>
> If you think that the bug of nodding is only impacting the reflective Path
> outcome? but the Cost outcome is fine? I would rather to complete my
> exercise for now as I'm running out of time.. I can fix this later
>
> Looking forward to hear your 'practical' expert advice, as I'm still
> beginner
>
> Thanks again
>
> Eyad
>
>
> -----Original Message-----
> From: pgrouting-users-bounces at lists.osgeo.org
> [mailto:pgrouting-users-bounces at lists.osgeo.org] On Behalf Of Stephen
> Woodbridge
> Sent: Friday, December 19, 2014 2:36 AM
> To: pgrouting-users at lists.osgeo.org
> Subject: Re: [pgrouting-users] Wierd results using pgr_kdijkstraPath
>
> On 12/18/2014 1:51 PM, AUS - Eyad wrote:
> > Also pgr_analyzeGraph function returned in the Messages Tab:
> >
> > NOTICE: ANALYSIS RESULTS FOR SELECTED EDGES:
> > NOTICE: Isolated segments: 7
> > NOTICE: Dead ends: 351
> > NOTICE: Potential gaps found near dead ends: 1
> > NOTICE: Intersections detected: 62
> > NOTICE: Ring geometries: 0
> >
> > I don't know if this is positive or negative, but would like to know your
> > feedback
> >
> > Maybe the isolated segments are lines which are not connected to the
> > network? Is there a way to visualize each group of the above lines?
>
> So this command adds columns "cnt" amd "chk" to the vertices_tmp table.
>
> Isolated segments are identified by the fact that both the start and end
> points are dead-ends:
>
> select *
> from edges a, vertices_tmp b, vertices_tmp c
> where a.source=b.id and a.target=c.id and b.cnt=1 and c.cnt=1;
>
> or maybe:
>
> select *
> from vertices_tmp a, edges b
> where a.chk>0 and st_dwithin(a.geom, b.geom, <distance>);
>
> Intersections detected indicates you have lines that cross but are not
> noded where they cross. You have to split all lines if they cross and
> make sure there is node at the intersection.
>
> There is a tool pgr_nodeNetwork() that can help, but there has recently
> been a big found in it and a patch posted with the ticket for the bug.
> https://github.com/pgRouting/pgrouting/issues/280
>
> -Steve
>
> > Eyad
> >
> >
> > -----Original Message-----
> > From: AUS - Eyad [mailto:b00038807 at aus.edu]
> > Sent: Thursday, December 18, 2014 9:54 PM
> > To: 'pgRouting users mailing list'
> > Subject: RE: [pgrouting-users] Wierd results using pgr_kdijkstraPath
> >
> > The function
> >
> > SELECT pgr_analyzeGraph('schema.network_noded',50,'geom');
> >
> > Returned "OK"
> >
> > Feel free to ask for any other details. I know it's not easy to get
> things
> > done remotely.
> >
> > Eyad
> >
> >
> > -----Original Message-----
> > From: pgrouting-users-bounces at lists.osgeo.org
> > [mailto:pgrouting-users-bounces at lists.osgeo.org] On Behalf Of Stephen
> > Woodbridge
> > Sent: Thursday, December 18, 2014 8:25 PM
> > To: pgrouting-users at lists.osgeo.org
> > Subject: Re: [pgrouting-users] Wierd results using pgr_kdijkstraPath
> >
> > Ok this sounds reasonable.
> >
> > Give this a try:
> >
> http://docs.pgrouting.org/dev/src/common/doc/functions/analyze_graph.html
> >
> > It is hard to diagnose problems remotely via the list.
> >
> > -Steve
> >
> > On 12/18/2014 10:48 AM, AUS - Eyad wrote:
> >> Here is st_astext(geom) function result (below table).
> >>
> >> For both createTopology and nodeNetwork functions, I used "50" as
> >> tolerance because my data unit is in millimeter. However, the network is
> >> done on CAD and fairly not poor in resolution.
> >>
> >> Is this what you wanted, or you need another layout/map? I attached many
> >> layouts/maps already in the previous 3 emails.. let me know if you were
> >> not able to visualize
> >>
> >> Eyad
> >>
> >> -----Original Message-----
> >> From: pgrouting-users-bounces at lists.osgeo.org
> >> [mailto:pgrouting-users-bounces at lists.osgeo.org] On Behalf Of Stephen
> >> Woodbridge
> >> Sent: Thursday, December 18, 2014 7:26 PM
> >> To: pgrouting-users at lists.osgeo.org
> >> Subject: Re: [pgrouting-users] Wierd results using pgr_kdijkstraPath
> >>
> >> Eyad,
> >>
> >> What does you geomerty look like?
> >>
> >> Select st_astext(geom) from edges limit 10;
> >>
> >> What value did you use for tolerance when creating your topology?
> >>
> >> What value did you use for tolerance when you noded your network?
> >>
> >> -Steve
> >>
> >> On 12/18/2014 10:17 AM, AUS - Eyad wrote:
> >>
> >> > And here I enclose below the resulted travel_costs' table of
> >>
> >> > pgr_dijkstra function:
> >>
> >> >
> >>
> >> > Note that Shortest path cost on original network (between the 2
> lines
> > of
> >>
> >> > the resulted vector feature) is around 250m (below - by converting
> from
> >>
> >> > millimeter to meter) whereas the sum of costs in the above table is
> >>
> >> > around 45m only
> >>
> >> >
> >>
> >> > Thanks..
> >>
> >> >
> >>
> >> > Eyad
> >>
> >> >
> >>
> >> > *From:*AUS - Eyad [mailto:b00038807 at aus.edu]
> >>
> >> > *Sent:* Thursday, December 18, 2014 7:02 PM
> >>
> >> > *To:* 'pgRouting users mailing list'
> >>
> >> > *Subject:* RE: [pgrouting-users] Wierd results using
> pgr_kdijkstraPath
> >>
> >> >
> >>
> >> > Here is a prt_sc after trying pgr_dijkstra as follows:
> >>
> >> >
> >>
> >> > SELECT seq, id1 as path, (b.geom) as geom, cost FROM pgr_dijkstra(
> >>
> >> >
> >>
> >> > 'SELECT id, source, target, (st_length(geom) * 0.001) as cost
> FROM
> >>
> >> > schema.network_noded',
> >>
> >> >
> >>
> >> > 336, (SELECT MAX(id) FROM schema.l1_pv1), false, false
> >>
> >> >
> >>
> >> > ) a, schema.network_noded b
> >>
> >> >
> >>
> >> > WHERE a.id1=b.id
> >>
> >> >
> >>
> >> > As you may see, there is only too little parts of the network's
> lines
> >>
> >> > left (on the sides of the layout)! No route is visible
> >>
> >> >
> >>
> >> > Hope this clarifies..
> >>
> >> >
> >>
> >> > Eyad
> >>
> >> >
> >>
> >> > *From:*AUS - Eyad [mailto:b00038807 at aus.edu]
> >>
> >> > *Sent:* Thursday, December 18, 2014 6:29 PM
> >>
> >> > *To:* 'pgRouting users mailing list'
> >>
> >> > *Subject:* RE: [pgrouting-users] Wierd results using
> pgr_kdijkstraPath
> >>
> >> >
> >>
> >> > Hi Daniel,
> >>
> >> >
> >>
> >> > Enclosed are 3 maps (1^st prt_sc with the original network, 2^nd &
> 3^rd
> >>
> >> > prt_sc with the resulted network)
> >>
> >> >
> >>
> >> > Clearly, the majority of the network has faded away
> >>
> >> >
> >>
> >> > Awaiting your feedback, I would work on 2^nd suggestion
> >>
> >> >
> >>
> >> > Regards,
> >>
> >> >
> >>
> >> > Eyad
> >>
> >> >
> >>
> >> > *From:*pgrouting-users-bounces at lists.osgeo.org
> >>
> >> > [mailto:pgrouting-users-bounces at lists.osgeo.org] *On Behalf Of
> >> *Daniel Kastl
> >>
> >> > *Sent:* Thursday, December 18, 2014 6:28 AM
> >>
> >> > *To:* pgRouting users mailing list
> >>
> >> > *Subject:* Re: [pgrouting-users] Wierd results using
> pgr_kdijkstraPath
> >>
> >> >
> >>
> >> > Hi Eyad,
> >>
> >> >
> >>
> >> > It's difficult to give an answer based on your query and problem
> >>
> >> > description only. I guess, that (still) your network topology is not
> >>
> >> > correct. It looks like a data problem.
> >>
> >> >
> >>
> >> > There are 2 things you could do for now:
> >>
> >> >
> >>
> >> > (1) Show us some image of your "weird de-attached "little" pieces"
> >>
> >> >
> >>
> >> > (2) Try a simple shortest path query with one start and one end
> point
> >>
> >> > and see if it works with pgr_dijkstra function for example.
> >>
> >> >
> >>
> >> > Daniel
> >>
> >> >
> >>
> >> > On Thu, Dec 18, 2014 at 7:37 AM, AUS - Eyad <b00038807 at aus.edu
> >>
> >> > <mailto:b00038807 at aus.edu>> wrote:
> >>
> >> >
> >>
> >> > Hello pgr_Experts,
> >>
> >> >
> >>
> >> > I'm trying to get all the routes from a source point (i.e. 336) to a
> >>
> >> > group of target/destination points (located at different edges/ends
> of
> >>
> >> > linestrings' network) using the below code:
> >>
> >> >
> >>
> >> > SELECT seq, id1 as path, id2 as node, id3 as edge, (b.geom) as geom,
> >>
> >> > cost FROM pgr_kdijkstraPath(
> >>
> >> >
> >>
> >> > 'SELECT id, source, target, (st_length(geom) * 0.001) as cost FROM
> >>
> >> > schema.network_noded',
> >>
> >> >
> >>
> >> > 336, (SELECT array_agg(id) FROM schema.l1_pv1), false, false
> >>
> >> >
> >>
> >> > ) a, schema.network_noded b
> >>
> >> >
> >>
> >> > WHERE a.id1=b.id <http://b.id>
> >>
> >> >
> >>
> >> > It's resulting a weird de-attached "little" pieces of my original
> >>
> >> > nodded_network! However, the number of resulted paths is equal to
> the
> >>
> >> > target/destination points. Please advise:
> >>
> >> >
> >>
> >> > 1)What potential mistake I may have committed?
> >>
> >> >
> >>
> >> > 2)Does it mean that all the calculated travel_cost(s) are wrong (as
> > they
> >>
> >> > are reflected/represented by wrong linestrings)?
> >>
> >> >
> >>
> >> > I'm using QGIS 2.4.0 and pgRouting pg93-binaries-2.4.0
> >>
> >> >
> >>
> >> > I found similar question on this list of pgRouting users, asked by
> >>
> >> > Antonio last October
> >>
> >> >
> >>
> (http://lists.osgeo.org/pipermail/pgrouting-users/2014-October/001992.html
> >>
> >> > ), but obviously the question is not answered yet?
> >>
> >> >
> >>
> >> > Regards..
> >>
> >> >
> >>
> >> > Eyad
> >>
> >> >
> >>
> >> >
> >>
> >> > _______________________________________________
> >>
> >> > Pgrouting-users mailing list
> >>
> >> > Pgrouting-users at lists.osgeo.org
> > <mailto:Pgrouting-users at lists.osgeo.org>
> >>
> >> > http://lists.osgeo.org/mailman/listinfo/pgrouting-users
> >>
> >> >
> >>
> >> >
> >>
> >> > --
> >>
> >> >
> >>
> >> > Georepublic UG & Georepublic Japan
> >>
> >> > eMail: daniel.kastl at georepublic.de
> <mailto:daniel.kastl at georepublic.de>
> >>
> >> > Web: http://georepublic.info
> >>
> >> >
> >>
> >> >
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> >>
> >> >
> >>
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> >>
> >> >
> >>
> >> >
> >>
> >> >
> >>
> >> > _______________________________________________
> >>
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> >>
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> >>
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> >>
> >> >
> >>
> >> _______________________________________________
> >>
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> >>
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> >>
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> >>
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