[Insight-users] regid transformation matrix

[Henry]

Hi I am using "LandmarkInitializedMutualInformationRegistration" from
InsightApplications-3.4.0 and I have one question about the
transformation matrix from registration results: although I choose
rigid transformation, the transformation matrix are not seemed to be
orthogonal, for example:
0.999982 0.00137216 -0.00581659
-0.00133902 0.999983 0.0056975
0.00582431 -0.00568961 0.999967

I guess it is because affine transformation is used even for rigid
registration? How to use rigid transformation instead?

Thanks!
Henry