Opencv python HoughLinesP奇怪的结果

我试图获得他们在this HoughLinesP过滤器教程中得到的相同结果.我拍摄了相同的图像和相同的阈值,如下所示:

import cv2
from line import Line
import numpy as np

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

Line类是一个自定义类,它不会做任何有趣的事情只计算一些东西并且可以画线.
 然后我得到这两张图片:enter image description here
enter image description here

所以你可以看到我在图像的中间只有一条litle线.

不确定出了什么问题.我错过了什么?

谢谢.

注意:由于您链接了OpenCV 2.4.x的教程,我最初假设您还使用OpenCV 2.4.11编写了代码.事实证明,您实际上正在使用OpenCV 3.x.请记住,2.x和3.x之间的API有微妙的变化.

你不正确地拨打HoughLinesP.

根据文档,Python函数的签名是:

cv2.HoughLinesP(image, rho, theta, threshold[, lines[, minLineLength[, maxLineGap]]]) → lines

如果我们在您的通话中标记参数,我们会得到以下结果:

lines = cv2.HoughLinesP(cannied, rho=1, theta=np.pi / 180
    , threshold=80, lines=30, minLineLength=10)

但是,正确移植到Python的C代码将是

lines = cv2.HoughLinesP(cannied, rho=1, theta=np.pi / 180
    , threshold=80, minLineLength=30, maxLineGap=10)

Result

Canny类似的情况

cv2.Canny(image, threshold1, threshold2[, edges[, apertureSize[, L2gradient]]]) → edges

再次,让我们标记参数:

cannied = cv2.Canny(img, threshold1=50, threshold2=200, edges=3)

但它应该是:

cannied = cv2.Canny(img, threshold1=50, threshold2=200, apertureSize=3)

然而,这对输出没有影响,因为apertureSize的默认值是3.

最后,正如我们在Vasanthnamatoj中所确定的那样,cv2.HoughLinesP生成的输出格式有所不同:

>在2.4中它看起来像[[[x1,y1,x2,y2],[…],…,[…]]]
>在3.x中它看起来像[[[x1,y1,x2,y2]],[[…]],…,[[…]]]

我添加了一个简短的get_lines函数来将这些行转换为两个版本中的一致布局([[x1,y1,x2,y2],[…],…,[…]]).

适用于两个OpenCV版本的完整脚本:

import cv2
import numpy as np


def get_lines(lines_in):
    if cv2.__version__ < '3.0':
        return lines_in[0]
    return [l[0] for l in lines]


img = cv2.imread('building.jpg')
img_gray = gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

cannied = cv2.Canny(img_gray, threshold1=50, threshold2=200, apertureSize=3)
lines = cv2.HoughLinesP(cannied, rho=1, theta=np.pi / 180, threshold=80, minLineLength=30, maxLineGap=10)

for line in get_lines(lines):
    leftx, boty, rightx, topy = line
    cv2.line(img, (leftx, boty), (rightx,topy), (255, 255, 0), 2)

cv2.imwrite('lines.png',img)
cv2.imwrite('canniedHouse.png',cannied)
cv2.waitKey(0)
cv2.destroyAllWindows()
https://stackoverflow.com/questions/36452491/opencv-python-houghlinesp-strange-results

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