I am trying to wrap my head around the confusion with regards to
sform and transformations, and was hoping you could clear up something for me.
My understand is that:
qformtransformation (as stored in a NIfTI header) relates the voxel co-ordinates (in mm) to scanner space (aka some frame of reference on the scanner), and is a rigid transform.
sformtransformation relates the voxel co-ordinates to some standard space (eg. MNI space), is an affine transform.
- Sometimes a NIfTI image has one or both, and therefore MRtrix3 picks one based on predefined rules defined here.
My question is: When looking at the transform output my
mrinfo (in the absence of simplifying greater than 90 degree transformations through stride changes), is this simply the
sform transform (depending on which is available given the above rule)? Or is there some relation to this transform and the
If it is, by definition does this mean that if the transformation displayed by
mrinfo is affine, then it must be the
sform transform? Or can the
qform be set to an affine transform even if it is not supposed to be?