title: I am trying to use cv2.projectPoints() but I am getting an error
body: <p>This is the error:</p>
  <pre><code>imgpts, jac = cv2.projectPoints(axis, rvecs, tvecs, mtx, dist)
  cv2.error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\calib3d\src\calibration.cpp:603: 
  error: (-5:Bad argument) Rotation must be represented by 1x3 or 3x1 floating-point rotation vector, or 
  3x3 rotation matrix in function 'cvProjectPoints2Internal'
  </code></pre>
  <p>This is my code:</p>
  <pre><code>axis = np.float32([[3, 0, 0], [0, 10, 0], [0, 0, -50]]).reshape(-1, 3)#axis of coordinates
  
  # PnP calculates the rotation vector and translation vector
  rvecs, tvecs, inliers = cv2.solvePnP(obj_points, image_points, mtx, dist)
  
  print(f&quot;mtx shape: {mtx.shape}, tvecs shape: {tvecs.shape}&quot;)
  print(f&quot;mtx:\n {mtx}&quot;)
  print(f&quot;tvecs:\n {tvecs}&quot;)
  
  # Calculate the coordinates of 3D points projected on 2D image plane
  imgpts, jac = cv2.projectPoints(axis, rvecs, tvecs, mtx, dist)
  </code></pre>
  <p>And this is the outpot:</p>
  <pre><code>mtx shape: (3, 3), tvecs shape: (3, 1)
  
  mtx:
   [[1.71223579e+03 0.00000000e+00 1.02990683e+03]
   [ 0.00000000e+00 1.70818827e+03 7.83446773e+02]
   [ 0.00000000e+00 0.00000000e+00 1.00000000e+00]]
  
  tvecs:
   [[-0.09038089]
   [ -0.05386737]
   [ -0.01652085]]
  </code></pre>
  <p>I dont have any idea about how to solve it. It seem like the problem is in the shape of the arguments. But when i checked they seem in the right shape. so I dont know what is the problem, but if you do it be very helpful.</p>