[pgrouting-users] pgrouting Dijkstra: non-vertex data routing

[Daniel Kastl]

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> 

> There are some good resources on anitagraser.com and this post
> shows how to associate a point (in this case airports) to the
> nearest network node and then solve the routing problem: 
> http://anitagraser.com/2011/02/12/drive-time-isochrones/
> 

Be aware that the blog post is relatively old and uses an outdated
version of pgRouting.

Also the function mentioned there does not limit the search area by
BBOX, so for large tables it might be slow(er).
It's better to use KNN to find nearest nodes, and you can find an
example in the workshop:
http://workshop.pgrouting.org/chapters/wrapper.html#route-between-lat-lon-points-and-return-ordered-geometry-with-heading

SELECT id::integer FROM ways_vertices_pgr
    ORDER BY the_geom <-> ST_GeometryFromText(POINT(x y),4326) LIMIT 1;

Another option is to use TRSP function, because it does not require to
start from a node but can start from "within" an edge:
http://docs.pgrouting.org/2.0/en/src/trsp/doc/index.html#trsp

Best regards,
Daniel


- -- 
Georepublic UG & Georepublic Japan
eMail: daniel.kastl at georepublic.de
Web: http://georepublic.info
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