Hi,
No, that's not the implementation that we use.
See: http://www.fmrib.ox.ac.uk/analysis/techrep/tr99mj1/tr99mj1/node5.html
All the best,
Mark
On 31 Jan 2012, at 22:56, Yiou Li wrote:
> Hi Mark,
>
> Thanks for the prompt feedback! As I understand, the rmsdiff measure
> is invariant to the order of transform matrices just as |X1 - X2|^2 is
> symmetric to both variables?
>
> Thanks!
> Leo
>
> On Tue, Jan 31, 2012 at 2:44 PM, Mark Jenkinson <[log in to unmask]> wrote:
>> Dear Leo,
>>
>> There is no right answer.
>> The two different ways just average over a slightly different
>> spherical ROIs. However, the difference will be pretty minor
>> and I can't think of an example where these small differences
>> would matter.
>>
>> All the best,
>> Mark
>>
>>
>>
>> On 31 Jan 2012, at 22:08, Yiou Li wrote:
>>
>>> Hi Mark,
>>>
>>> I want to use rmsdiff to measure the difference between image X1 and
>>> X2 in terms of affine linear transformation, to do that, I ran flirt
>>> to register X1 to X2, taking X2 as reference image and get the
>>> transformation xmat_1_to_2, now I got two slightly different number by
>>> running:
>>>
>>> 1. rmsdiff xmat_identity xmat_1_to_2 X2
>>> 2. rmsdiff xmat_1_to_2 xmat_identity X2
>>>
>>> Can you please advise which one is the correct order in this case?
>>>
>>> Thanks in advance!
>>> Leo
>>>
>
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