手势控制错误：AttributeError：'module'对象没有属性'convexityDefects'

Question

我正在尝试this tutorial进行手势识别和控制

直到我将这部分添加到代码中才能正常运行：

defects = cv2.convexityDefects(cnt,hull)

mind=0
maxd=0

for i in range(defects.shape[0]):
    s,e,f,d = defects[i,0]
    start = tuple(cnt[s][0])
    end = tuple(cnt[e][0])
    far = tuple(cnt[f][0])
    dist = cv2.pointPolygonTest(cnt,centr,True)
    cv2.line(img,start,end,[0,255,0],2)
    cv2.circle(img,far,5,[0,0,255],-1)

print(i)
i=0

由于某种原因，python正在为convexityDefects函数显示此错误。

Traceback (most recent call last):  
File "F:\Python programs\python ocv\gesture detect.py", line 37, in  
<module> defects = cv2.convexityDefects(cnt,hull) AttributeError:  
'module' object has no attribute 'convexityDefects'  

我安装了最新版本的numpy，scipy和cv2。如果我只注释掉这段代码就可以了。