[pgrouting-users] PgRouting-Problems with own OSM-data

[Kai Behncke]

Hi Stephen, Hi mailinglist,

thank you very much for that hint. With that way I was able to find out that there are far too many "dead ends" in my data, so I think this is the proof that it`s really a data problem?

http://www.selbstverwaltung-bundesweit.de/too_many_dead_ends.png

I made this test also with the victoria-data, there everything is correct.

To get a step further I work now with a very small dataset (just 35
geometries) (as you can see in the screenshot above) but without success so far.

>If you have a lot of red dots between segments
>that should be joined, you probably need to rebuild your vertices tmp
>table with a larger tolerance.

I did that, I changed 0.001 in

SELECT assign_vertex_id('auswahl_os', 0.001, 'the_geom', 'gid');

with the values 0.005, 0.01, 0.05, 0.5, 5, 50 and so on

The values <50 still show very many "dead ends". If I have higher values then
the amount of vertices in general decreases, so a routing is also not possible anymore, you can see it here:


http://www.selbstverwaltung-bundesweit.de/not_enough_vertices.png


Maybe the following is a hint:

If I use
SELECT assign_vertex_id('auswahl_os', 0.001, 'the_geom', 'gid');

with my data I get 54 entries in the vertices_tmp-table.
(an extract of the victorie-data (50 geometries) just gives 42 entries in
vertices_tmp).

What could be the reason that I get so many entries mith my data?

What exactly stands the value 0.001 for?

I really don`t understand what could be wrong with my geodata :-(

Might it be possible that someone would have a look to these 54 geometries
(4 eyes see more than two) ??

Puh....if I get it I will really write a huge tutorial in the pgrouting-wiki.

Best regards, Kai



-------- Original-Nachricht --------
> Datum: Wed, 15 Apr 2009 13:24:21 -0500
> Von: Stephen Woodbridge <woodbri at swoodbridge.com>
> An: Kai Behncke <Kai-Behncke at gmx.de>
> CC: pgrouting-users at lists.postlbs.org
> Betreff: Re: [pgrouting-users] PgRouting-Problems with own OSM-data

> Kai,
> 
> First off you probably need to build some diagnostic tools to help you 
> understand the problem better, especially to help you determine if it is 
> a data problem. I find two tools that are easy to build and help a lot. 
> You can see them in action here:
> http://imaptools.com/leaddog/routing/dd.html
> Zoom into a city, open the layerswitcher and select "Just the Streets" 
> and "Dead Ends"
> 
> 1) create a mapfile that displays the street segments from the routing 
> database and add this as an optional base layer. You might want to add 
> color oneway streets a different color, but in general keep the display 
> simple and probably single pixel lines. You might label the segments 
> with their UID so you can go back to the database and query them in
> detail.
> 
> 2) add a column cnt integer to the vertices_tmp table and update it with 
> the count of segments that reference that node. Maybe something like this:
> 
> alter table vertices_tmp add column cnt integer;
> update vertices_tmp set cnt=0;
> update vertices_tmp set cnt=cnt+1 where streets.source=id;
> update vertices_tmp set cnt=cnt+1 where streets.target=id;
> 
> Now create a mapfile layer for points and display the vertices_tmp
> 
> LAYER
>    NAME "deadends"
>    TYPE POINT
>    CONNECTIONTYPE "postgis"
>    CONNECTION ...
>    DATA ...
>    CLASSEXPRESSION "cnt"
>    CLASS
>      EXPRESSION "cnt=1"
>      STYLE
>        SYMBOL "circle"
>        SIZE 5
>        COLOR 255 0 0
>      END
>    END
>    CLASS
>      EXPRESSION "cnt>2"
>      STYLE
>        SYMBOL "circle"
>        SIZE 3
>        COLOR 0 255 0
>      END
>    END
> END
> 
> This will display red dots at dead ends and green dots as good 
> connections be segments. If you have a lot of red dots between segments 
> that should be joined, you probably need to rebuild your vertices tmp 
> table with a larger tolerance.
> 
> It is very hard to debug a large black box like a router without having 
> some tools that can give you some better insight as to what is going on.
> 
> -Steve
> 

-- 
Neu: GMX FreeDSL Komplettanschluss mit DSL 6.000 Flatrate + Telefonanschluss für nur 17,95 Euro/mtl.!* http://dslspecial.gmx.de/freedsl-surfflat/?ac=OM.AD.PD003K11308T4569a