我正在尝试从轮廓创建 mask ，但出现 C++ 错误。
使用 OS X Yosemite、Python 2.7.10、OpenCV 3.1.0。
def create_mask(img, cnt):
'''Create a mask of the same size as the image
based on the interior of the contour.'''
mask = np.zeros((img.shape[0], img.shape[1]), np.uint8)
print("create_mask, cnt=%s" % cnt)
cv2.drawContours(mask, [cnt], 0, (0, 255, 0), -1)
return mask
print("Creating mask from contour %s, on raw shape %s" % (page_contour, raw.shape))
page_mask = create_mask(raw, page_contour)
输出(错误见底部):
Creating mask from contour [[ 1626. 360.]
[ 1776. 3108.]
[ 126. 3048.]
[ 330. 486.]], on raw shape (3840, 2160, 3)
create_mask, cnt=[[ 1626. 360.]
[ 1776. 3108.]
[ 126. 3048.]
[ 330. 486.]]
OpenCV Error: Assertion failed (npoints > 0) in drawContours, file /tmp/opencv320160309-92782-1efch74/opencv-3.1.0/modules/imgproc/src/drawing.cpp, line 2380
Traceback (most recent call last):
File "./books.py", line 209, in <module>
page_mask = create_mask(raw, page_contour)
File "./books.py", line 123, in create_mask
cv2.drawContours(mask, [cnt], 0, (0, 255, 0), -1)
cv2.error: /tmp/opencv320160309-92782-1efch74/opencv-3.1.0/modules/imgproc/src/drawing.cpp:2380: error: (-215) npoints > 0 in function drawContours
docs说它应该得到一个数组数组，这似乎是我给它的。那怎么了？
代码是从 OpenCV 2.x 移植过来的。
最佳答案
我认为您在 cnt 周围添加了额外的 []
应该是
cv2.drawContours(mask, cnt, 0, (0, 255, 0), -1)
因为 cnt 已经是数组的数组，但是 [cnt] 是数组的数组的数组，这是行不通的
更新以上代码
你应该首先将你的轮廓转换为 numpy 数组
ctr = numpy.array(cnt).reshape((-1,1,2)).astype(numpy.int32)
cv2.drawContours(mask, [ctr], 0, (0, 255, 0), -1)
检查文档 here
contours is a Python list of all the contours in the image. Each individual contour is a Numpy array of (x,y) coordinates of boundary points of the object.
关于python - OpenCV 3.1 绘制轮廓 '(-215) npoints > 0'，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35902139/