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Fix houghlines.py when no lines found

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In the C++ equivalent of this example a check is made whether the vector (here in Python we have a list) actually has any lines in it that is whether the Hough lines function has managed to find any in the given image. This check is missing for the Python example and if no lines are found the application breaks.
This commit is contained in:
Aleksandar Atanasov 2016-06-02 11:00:23 +02:00
parent cf0df733da
commit 14deab252b
1 changed files with 11 additions and 10 deletions
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21
samples/python/houghlines.py
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@ -36,16 +36,17 @@ if __name__ == '__main__':
else: # HoughLines
lines = cv2.HoughLines(dst, 1, math.pi/180.0, 50, np.array([]), 0, 0)
a,b,c = lines.shape
for i in range(a):
rho = lines[i][0][0]
theta = lines[i][0][1]
a = math.cos(theta)
b = math.sin(theta)
x0, y0 = a*rho, b*rho
pt1 = ( int(x0+1000*(-b)), int(y0+1000*(a)) )
pt2 = ( int(x0-1000*(-b)), int(y0-1000*(a)) )
cv2.line(cdst, pt1, pt2, (0, 0, 255), 3, cv2.LINE_AA)
if lines != None:
a,b,c = lines.shape
for i in range(a):
rho = lines[i][0][0]
theta = lines[i][0][1]
a = math.cos(theta)
b = math.sin(theta)
x0, y0 = a*rho, b*rho
pt1 = ( int(x0+1000*(-b)), int(y0+1000*(a)) )
pt2 = ( int(x0-1000*(-b)), int(y0-1000*(a)) )
cv2.line(cdst, pt1, pt2, (0, 0, 255), 3, cv2.LINE_AA)
cv2.imshow("source", src)
cv2.imshow("detected lines", cdst)