Camera Calibration Code - Opencv Error: Assertion Failed

I'm trying to execute this code for camera calibration. This code is detecting corners but after that error is coming. OpenCV Error: Assertion failed (nimages > 0) in unknown

Solution 1:

In your code you have:

objpoints = []

but you never append anything to it. You are missing:

objpoints .append(objp )

after the line

imgpoints.append(corners)

One extra thing, you should check if they have points before doing calibration like:

iflen(objpoints) == len(imgpoints) andlen(objpoints) > 0:
    ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape[::-1],None,None)
else:
    print("not enough points to calibrate")