Hi Doug,
I tried to do what you recommended but I am encountering an inconsistency.
(Note: I obtain the same results in R (with ginv() ) and Matlab (with
pinv() ) )
Could you please have a look at the code and the values please? I don't
know what else to do right now... (it is possible to copy paste everything
in Matlab)
***************
TalXFM = [1.040797, 0.011370, -0.069615, -0.863770;0.031794, 0.939578,
0.254677 ,-32.126083; 0.048458, -0.236663 ,1.101207, -20.946930];
Norig = [-1.00000 , -0.00000 , -0.00000 , 130.38606 ;-0.00000 ,
0.00000 , 1.00000, -109.95447 ;-0.00000, -1.00000 , 0.00000 ,
150.14441 ; 0.00000, 0.00000 , 0.00000 , 1.00000];
Torig = [-1.00000 , 0.00000 , 0.00000 , 128.00000; 0.00000 , 0.00000
, 1.00000, -128.00000; 0.00000 , -1.00000 , 0.00000 , 128.00000;
0.00000 , 0.00000 , 0.00000 , 1.00000];
W = TalXFM * Norig * inv(Torig);
Volume_RAS = [1, -30, 1, 1];
MNI_Talairach = W * Volume_RAS' % Coincides with Tkmedit
% MNI_Talairach = (0.9133; -37.3562; 7.5331)
Volume_RAS = pinv(W)*MNI_Talairach % DOES NOT COINCIDE
% Volume_RAS = (0.4324; -2.9014; 8.7350; 3.8992) >> shouldn't be
[1, -30, 1, 1]; ?
********************
Is the transformation two-way? Should it be?
Many thanks again for your help,
Gari
On Wed, Mar 13, 2013 at 10:15 AM, Douglas Greve
<gr...@nmr.mgh.harvard.edu>wrote:
> Hi Gary, you would use the MNI305 space as the common space. Eg, Case 2
> shows you how to go from RAS of a subject to MNI305 space. You would
> reverse that to go from MNI305 space to another subject's RAS space thus
> allowing a RAS-RAS transform. If you have a surface overlay for a subject,
> you can use mri_surf2surf to transfer it to another subject.
> doug
>
>
> On 3/12/13 11:54 PM, Garikoitz Lerma-Usabiaga wrote:
>
> Thanks Doug,
> I've seen the page, but I understand that everything is within the same
> subject. I want to find the equivalencies between subjects. I mean, the
> plane y = 30 in fsaverage, will correspond to a plane with a bigger Y for a
> larger head (could be defined anatomically, the most outer point of the
> hippocampus, for example.
>
> When finding equivalencies for surface ROIs from one subject to another
> we used label2label for example. If I have an overlay in volume space, how
> should I "move" it to another subject?
>
> Thanks again,
> Gari
>
>
>
> On 12/03/2013, at 20:29, Douglas Greve <gr...@nmr.mgh.harvard.edu> wrote:
>
> Hi Gary, check out this wiki page and let me know if you still have
> questions
> http://surfer.nmr.mgh.harvard.edu/fswiki/CoordinateSystems
> doug
>
> On 3/12/13 8:04 PM, Garikoitz Lerma-Usabiaga wrote:
>
> Hi!
> how can I translate a coordinate in talairach space of one subject
> (Colin27), to every subject in a study? For example, I would like to know
> where is the coordinate Y = +30 Talairach of Colin27 in Subject_00,
> Subject_01, etc.
>
> Should I use vol2vol to create a volume for every subject? Is there any
> direct method with register matrices or something like that?
>
> Thank you very much,
> Gari
>
>
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