BrainVISA

Hello,

I noticed that, in some cases, Brainvisa computes a Tailarch transformation that is not rigid. Can this be true?
Shouldn't it be just a rigid tranformation?

Thanks
Tiziano

Hi Tiziano,
The Talairach transform computed by Morphologist is a combination of a rotation (rigid) and scaling factors which may be different on the 3 axes. It is anyway an affine transform.
Denis

Thanks, is there a good reason to have the scaling factors? I Thought that theoretically should be rigid..

I thought it was just an aligment to the CA-CP-IH axes (which is what I need), but if it's not rigid I guess it is actually an affine registration to the Tailarach atlas right?

Thanks a lot
Tiziano

The scaling factors are used to fit the global bounding box of the brain.
Denis