1

This is my first question. I wonder that, how can I get length of line's segment?

enter image description here

Yellow line is my road. blue Points are my start and end points. So I want to measure point1 and point2 between route.This points are variable. So I ll select them. How can I get it with postgis query ?

I UPDATE MY QUESTION. :)

  • 1
    Do you have an attribute that distinguishes the blue from the yellow? – John Powell Nov 1 '14 at 14:02
  • I update my question. I have only one line. Blue points on yellow line. – CbsHs Nov 1 '14 at 18:47
2

I found my solution.

select ST_Length(ST_AsText(ST_Line_Substring(line,ST_Line_Locate_Point(line,ST_ClosestPoint(line,strtpoint )),ST_Line_Locate_Point(line,ST_ClosestPoint(line,endpoint ))))as cizgi_uzunlugu FROM ( SELECT 'POINT(30 30)'::geometry As strtpoint,'POINT(110 0)'::geometry As endpoint,'LINESTRING(0 0, 0 30, 30 30, 30 50, 90 50, 90 60, 110 60, 110 0, 150 0, 150 30)'::geometry As line) As foo;
1

Here's what I would try:

  1. ST_PointN() to get desired vertices
  2. ST_MakeLine with points acquired in previous step
  3. ST_Length with line acquired in previous step to get the final length.

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