compatibility issue with contourArea in openCV 3

Question

I am trying to do a simple area calculation of contours I get from findContours. My openCv version is 3.1.0

My code is:

cc = cv2.findContours(im_bw.c         


        

Answer 1

This problem is caused by the different return value of cv2.findContours in different OpenCV versions.

In OpenCV 4.0.0, this error may looks like cv2.error: OpenCV(4.0.0) C:\projects\opencv-python\opencv\modules\imgproc\src\convhull.cpp:137: error: (-215:Assertion failed) total >= 0 && (depth == CV_32F || depth == CV_32S) in function 'cv::convexHull'

You can find a detailed explanation and solutions here: How to use `cv2.findContours` in different OpenCV versions?