Output vector of rotation vectors (Rodrigues ) estimated for each
pattern view (e.g. std::vectorcv::Mat>). That is, each i-th rotation
vector together with the corresponding i-th translation vector (see
the next output parameter description) brings the calibration pattern
from the object coordinate space (in which object points are
specified) to the camera coordinate space. In more technical terms,
the tuple of the i-th rotation and translation vector performs a
change of basis from object coordinate space to camera coordinate
space. Due to its duality, this tuple is equivalent to the position of
the calibration pattern with respect to the camera coordinate space.
將世界系（target）下的點轉換到相機系下。
標定板原點在相機系下的位置。