def rotVector2Matrix(vec):
return axisAndAngle2RotMatrix(vec, np.linalg.norm(vec))<EOL>
better use cv2.Rodrigues(rvec)[0] for that job...

the angle is given as the magnitude of the rot vector,
see https://www.safaribooksonline.com/library/view/learning-opencv/9780596516130/ch11s05.html