[postgis-users] - The greater length River inside one Watershed

[Marcello Benigno]

Hello Friends,

The problem was not solved yet, but with the help of:
http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html

I could find the following rivers of my batch point (test1.png), I would
find just the opposite result, the longest length in the opposite direction,
that is the longest river inside the basin (in yellow - test2.png).

-- the word rio is river in Portuguese
WITH RECURSIVE walk_network(gid, the_geom) AS (
    SELECT gid, the_geom
    FROM rio
    WHERE gid = 311
  UNION ALL
    SELECT n.gid, n.the_geom
    FROM rio n, walk_network w
    WHERE ST_DWithin(ST_EndPoint(w.the_geom),ST_StartPoint(n.the_geom),0.01)
  )
SELECT *
FROM walk_network;

I tried to create a view with the direction reversed my geometry with
ST_Reverse() and apply the same function as before, but unsuccessfully.

Thanks in advance,
-- 
*Marcello Benigno B. de Barros Filho*
Prof. do Curso Superior de Tecnologia em Geoprocessamento - IFPB
Mestre em Ciências Geodésicas e Tecnologias da Geoinformação - UFPE
http://profmarcello.blogspot.com
http://about.me/marcello.benigno
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