[Solved] cv2.error: OpenCV(4.5.1) XXX\shapedescr.cpp:315: error: (-215:Assertion failed) npoints >= 0 &&……

Error coming in the code

Traceback (most recent call last):
  File "D:/pythonProjects/Object_movement/object_movement.py", line 88, in <module>
    c = max(cnts, key=cv2.contourArea)
cv2.error: OpenCV(4.5.1) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-i1s8y2i1\opencv\modules\imgproc\src\shapedescr.cpp:315: error: (-215:Assertion failed) npoints >= 0 && (depth == CV_32F || depth == CV_32S) in function 'cv::contourArea'

Reason of coming to this error

In the new version of cv2 Findcontours returns two values. That’s why return of [0] is contour instead of [1]

Code having error:

cnts = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL,
                            cv2.CHAIN_APPROX_SIMPLE)
cnts=cnts[1]

Error Free Code

cnts, hierarchy = cv2.findContours(mask.copy(), cv2.RETR_EXTERNAL,
                                       cv2.CHAIN_APPROX_SIMPLE)
Ranjeet Singh Rawat
Ranjeet Singh Rawat

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