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VersorRigid3DTransform returns 3 translational motion and a versor (unit
quaternion) for a total of 6 parameters, and the QuaternionRigidTransform
returns 3 translational motion and a quaternion for a total of 7 parameters.

Please correct me if I'm wrong.  From my understanding, a versor alone can
represent any rotation in the 3D space.  However, I could only find
equations that converts from Quaternion to Euler angles but not from Versor
to Euler angles.  Does it mean that there is something missing in the versor
to represent rotational motion in the 3D space?
Is there certain rotational motion out there that can be covered by the
QuaternionRigidTransform registration but not by the VersorRigid3DTransform
registration?

Thanks.

Regards,
Brandon

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<p>Dear Experts,</p>
<div>I am trying to perform 3D rigid registration for images that have both translational and rotational motion.&nbsp; However, I am very confused about the two different transforms.&nbsp; I would really appreciate if someone can shed some light.</div>

<p>From the ITK documentation and example code, I understand that VersorRigid3DTransform returns 3 translational motion and a versor (unit quaternion) for a total of 6 parameters, and the QuaternionRigidTransform returns 3 translational motion and a quaternion for a total of 7 parameters.</p>

<p>Please correct me if I&#39;m wrong.&nbsp; From my understanding, a versor alone can represent any rotation in the 3D space.&nbsp; However, I could only find equations that converts from Quaternion to Euler angles but not from Versor to Euler angles.&nbsp; Does it mean that there is something missing in the versor to represent rotational motion in the 3D space?</p>

<div>Is there certain rotational motion out there that can be covered by the QuaternionRigidTransform registration but not by the VersorRigid3DTransform registration?</div>
<div>&nbsp;</div>
<div>Thanks.</div>
<div>&nbsp;</div>
<div>Regards,</div>
<div>Brandon</div>
<div>&nbsp;</div>
<div><br>&nbsp;</div>

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