[Insight-users] Quaternion vs. Versor

[Li, George (NIH/NCI)]

Luis:

For 3D image registration, it is suggested to use VersorRigid3DTransform
and VersorRigid3DTransformOptimizer, a sub-class of
RegularStepGradientDescentBaseOptimizer.

In my application I would like to have the features from
GradientDescentOptimizer. 
In ITK, however, there is only a
QuaternionRigidTransformGradientDescentOptimizer.
Based on the relationship between versor and quaternion, a new class,
VersorRigid3DTransformGradientDescentOptimizer, could be built. Do you think
that a simple substitution of quaternion with versor would do the job?

I have to admit that I have not spent enough time looking into the
optimizers.

Thanks,

George