opencv - 如何修复错误：(-215:Assertion failed) npoints > 0 in function 'drawContours'

Question

绘制轮廓错误我正在尝试为图像中的对象绘制轮廓

(_, contours) = cv2.findContours(binary, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

# draw contours over original image
length = len(contours)
for c in range(length):
    cv2.drawContours(img,contours,c,(255,0,0),3)

cv2.namedWindow("output", cv2.WINDOW_NORMAL)
cv2.imshow("output", img)
cv2.waitKey(0)

我希望绘制所有轮廓，但我得到的实际结果是错误：

（-215：断言失败）函数“drawContours”中的 npoints > 0

标签： opencvopencv-contour

Answer 1

轮廓应该是 numpy 数组。将您的代码更改为：

for c in contours:
    cv2.drawContours(img,[c], 0, (255,0,0),3)