Hi Stephen,
>> And how do we judge rotations: is one
>> degree as bad as 1 mm ? Has anyone looked at that in a more systematic
>> fashion?
>
> One way is to just estimate the maximum displacement due to a rotation,
> given a standard head size, using arclength = radius*angle (in radians).
Ah yes, ... I had to check wikipedia again to be sure I understood, but
now I think I do. I have another question, though, which I think I need
in order to proceed here: what is the origin that the volume is rotated
around? In other words, is every single fMRI volume rotated around its
center, or one of the corners? I would expect the former, but I have
been wrong before. I checked spm_realign but did not find a clue, so any
hint is appreciated.
Best,
Marko
--
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Marko Wilke (Dr.med./M.D.)
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Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
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