Opencv python HoughLinesP strange results

Question

I\'m trying to get the same result they got in this tutorial for HoughLinesP filter. I took same images and same threshold values like this :

import cv2
fro         


        

Answer 1

As Dan's answer mentions, the arguments are not correctly specified in Canny and HoughLinesP.

Modified code:

import cv2
from line import Line
import numpy as np

img = cv2.imread('building.jpg',1)
cannied = cv2.Canny(img, 50, 200, apertureSize=3)
lines = cv2.HoughLinesP(cannied, 1, np.pi / 180, 80, minLineLength=30, maxLineGap=10)

for leftx, boty, rightx, topy in lines[0]:
    line = Line((leftx, boty), (rightx,topy))
    line.draw(img, (255, 255, 0), 2)

cv2.imwrite('lines.png',img)
cv2.imwrite('canniedHouse.png',cannied)
cv2.waitKey(0)
cv2.destroyAllWindows()

Output:

If you are using OpenCV-3+, use this for-loop instead since HoughLinesP returns a different output format [[[x1, y1, x2, y2]], [[...]]...[[...]]]

for l in lines:  #Modified to loop across all the lines
    leftx, boty, rightx, topy = l[0] #assign each line's values to variables
    line = Line((leftx, boty), (rightx,topy))
    line.draw(img, (255, 255, 0), 2)