[pgrouting-users] Wierd results using pgr_kdijkstraPath
Stephen Woodbridge
woodbri at swoodbridge.com
Thu Dec 18 14:36:15 PST 2014
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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