CODEWITHSUNDEEP
opencvimage-processingcomputer-vision
rockinfresh
rockinfresh

Reputation: 2106

Removal of vertical HoughLines/Detection of Horizontal HoughLines only

I wish to ask if there is a method to detect only the nearly horizontal Hough Lines or ignoring those nearly vertical Hough Lines? My code for the HoughLine now is as shown:

HoughLinesP(imagec, lines, 80, CV_PI/2, CV_THRESH_OTSU|CV_THRESH_BINARY, 25, 7);
for(size_t i = 0; i < lines.size(); i++)
    {
      Vec4i l = lines[i];
      line(imagec, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(255,255,255), 8, 8);
      line(imagelines, Point(l[0], l[1]), Point(l[2], l[3]), Scalar(255,255,255), 8, 8); //draw on black image as well
    }

However in the image, I am seeking only to detect horizontal lines, or at least near horizontal lines like by 2 to 4 cm. I am using CV_PI/2 for the theta parameter in the HoughLineP, hence the vertical lines/ near vertical lines are detected too.

Any suggestions, code samples, etc will be greatly appreciated. Thanks.

Upvotes: 5

Views: 11754

Answers (2)

bl4ckb1rd
bl4ckb1rd

Reputation: 143

Python version

import numpy as np
angle = np.arctan2(y2 - y1, x2 - x1) * 180. / np.pi

Upvotes: 9

Haris
Haris

Reputation: 14053

To remove vertical line

  • First find the angle for each line using the equation

    double Angle = atan2(y2 - y1, x2 - x1) * 180.0 / CV_PI;

  • Just ignore the line which has angle 90 degree(vertical line).

Done !.

Upvotes: 7

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