Hi,
All the sform and qform fields for avg152T1_brain.nii.gz are exactly the
same when I look at them. I've attached the relevant bits of fslhd
below.
What do you get?
We generally write out both qform and sform to be identical except where
they are initially set-up separately. The reason there are two
fields is
that qform was originally intended to store the scanner orientation
(like
that found in the dicom) and sform was intended to store standard-space
information. In order to be the most compatible with other software, at
present, we set them to be equal whenever possible (noting that the
sform
can store 12 dof transforms, but the qform can only store 6 dof ones).
If you are seeing different values in your standard images, then it
sounds
like they may have been corrupted.
All the best,
Mark
% fslhd /usr/local/fsl/data/standard/avg152T1_brain.nii.gz
...
qform_name MNI_152
qform_code 4
qto_xyz:1 -2.000000 0.000000 -0.000000 90.000000
qto_xyz:2 0.000000 2.000000 -0.000000 -126.000000
qto_xyz:3 0.000000 0.000000 2.000000 -72.000000
qto_xyz:4 0.000000 0.000000 0.000000 1.000000
qform_xorient Right-to-Left
qform_yorient Posterior-to-Anterior
qform_zorient Inferior-to-Superior
sform_name MNI_152
sform_code 4
sto_xyz:1 -2.000000 0.000000 0.000000 90.000000
sto_xyz:2 0.000000 2.000000 0.000000 -126.000000
sto_xyz:3 0.000000 0.000000 2.000000 -72.000000
sto_xyz:4 0.000000 0.000000 0.000000 1.000000
sform_xorient Right-to-Left
sform_yorient Posterior-to-Anterior
sform_zorient Inferior-to-Superior
file_type NIFTI-1+
On 27 Sep 2007, at 17:05, Diana Wallin wrote:
> Hi,
>
> Can someone explain to me the difference between qform_xorient,
> _yorient, _zorient and sform_xorient, _yorient, and _zorient?
>
> I'm confused as to why qform and sform differ in the xorient in the
> standard brain (avg152T1_brain.nii.gz), but in the data I am
> analyzing, both fields are always identical.
>
> Thanks in advance,
> Diana
>
>
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