So I'm trying to obtain hough lines on a chessboard, but the algorithm results in only one line being detected. I'm using python 2.7 and opencv 3.0. Here's the code:
def applyHoughLineTransform():
image1 = cv2.imread('pictures/board1.png',0)
image2 = cv2.imread('pictures/board2.png',0)
image3 = cv2.imread('pictures/board3.png')
image4 = cv2.imread('pictures/board4.png')
lines1 = cv2.HoughLines(image1,1,math.pi/180.0,5)
lines2 = cv2.HoughLines(image2,1,math.pi/180.0,5)
lines1 = lines1[0]
lines2 = lines2[0]
for rho,theta in lines1:
print ('Rho and theta:',rho,theta)
a = np.cos(theta)
b = np.sin(theta)
x0 = a*rho
y0 = b*rho
x1 = int(x0 + 1000*(-b))
y1 = int(y0 + 1000*(a))
x2 = int(x0 - 1000*(-b))
y2 = int(y0 - 1000*(a))
print (x1,y1)
print (x2,y2)
cv2.line(image3,(x1,y1),(x2,y2),(0,0,255),2)
for rho,theta in lines2:
a = np.cos(theta)
b = np.sin(theta)
x0 = a*rho
y0 = b*rho
x1 = int(x0 + 1000*(-b))
y1 = int(y0 + 1000*(a))
x2 = int(x0 - 1000*(-b))
y2 = int(y0 - 1000*(a))
cv2.line(image4,(x1,y1),(x2,y2),(0,0,255),2)
cv2.imwrite('pictures/board1.png',image1)
cv2.imwrite('pictures/board2.png',image2)
cv2.imshow('hough line 1',image3)
cv2.imshow('hough line 2',image4)
Here's the canny edge image on which i perform the hough line algorithm:
And here are the results:
As you can see, pretty lame. The canny algorithm seems to be providing really nice edges to operate on. I'm not entirely sure what I'm doing wrong. I imagine it has something to do with the arguments inputted into the houghLines function. If someone could point me in the right direction (or fix my problem entirely :) ) I would greatly appreciate it. Here's a link to the tutorial site I'm using: http://opencv-python-tutroals.readthedocs.org/en/latest/py_tutorials/py_imgproc/py_houghlines/py_houghlines.html
Canny()
in your code.. – a-Jays