A Question about the convert_to_aflw

[wangzixing1998]

hello, there a question about the function "convert_to_aflw". In the reference_3d_5_points_trans.npy. the Coordinate system is that : the X-axis is to the right， the X-axis is to the bottom, the Z-axis is facing away from the observer.
the code "rot_mat_2 = np.transpose(rotvec)" is the rotation matrix of the camera coordinate system to the world coordinate system.
I can 't understand why int the code "np.array([angle[0], -angle[1], -angle[2]])" Yaw and roll are Negative number.