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How to calculate slope, length and distance between hough lines?

asked 2017-05-08 06:12:42 -0500

Lavanya gravatar image

To detect lines from my image I used problabistic hough transform. I got 15 lines from my image. now I want to calculate slope, length of each line and to calculate distance between nearest lines? Can anyone suggest me ideas or share code? Thanks in advance

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answered 2017-05-08 06:31:19 -0500

berak gravatar image

updated 2017-05-08 06:33:04 -0500

really, this is not so much an opencv problem, but a maths one ..

houghlinesP already gives you the endpoints of the line,

Vec4i line = lines[i];
Point a(line[0], line[1]);
Point b(line[2], line[3]);


  • the slope is dy/dx , or

    float(b.y - a.y) / float(b.x - a.x);

  • the length is the euclidean distance, or:


no idea, what you mean with the distance, try to explain ?

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may be this

LBerger gravatar imageLBerger ( 2017-05-08 07:28:33 -0500 )edit

In my image I got two parallel lines. Now I calculated slope and length of each line respectively. I want to calculate distance between these two parallel lines.

Lavanya gravatar imageLavanya ( 2017-05-08 07:46:12 -0500 )edit

the distance is somewhat tricky. the link, @LBerger sent, assumes infinite lines, this probably won't work here.

by best guess, atm: take the shortest of the 4 point distances: a1,a2 a1,b2 b1,a2 b1,b2

berak gravatar imageberak ( 2017-05-09 03:33:44 -0500 )edit

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Asked: 2017-05-08 06:12:42 -0500

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Last updated: May 08 '17