Hi Gari,
The transformation actually consists of a 3 x 3 matrix and a 3 x 1 translation vector. The use of a 4 x 4 matrix allows the representation of an affine transformation as a matrix multiplication (http://en.wikipedia.org/wiki/Affine_transformation#Representation).
--Thomas
On Wed, Sep 11, 2013 at 4:21 PM, Garikoitz Lerma-Usabiaga garikoitz@gmail.com wrote:
Hi Doug, just a very naive question about coordinate change: why do we need the fourth component? I mean, shouldn't be the transformation matrix 3x3 instead of 4x4 for a coordinate change in 3D space? thanks! Gari
On Wed, Sep 11, 2013 at 12:52 AM, Douglas N Greve greve@nmr.mgh.harvard.edu wrote:
Hi Yang, I've computed a matrix that should do the trick. If you are in matlab, then
M = [ 0.9975 -0.0073 0.0176 -0.0429 0.0146 1.0009 -0.0024 1.5496 -0.0130 -0.0093 0.9971 1.1840 0 0 0 1.0000] P305 = [MNI305x MNI305y MNI305z 1]'; P152 = M*P305
Can you give this a shot and see if it makes sense? It will probably be hard to tell since the matrix is pretty close to identity.
doug
On 09/10/2013 05:17 PM, Yang, Daniel wrote:
Thanks, Doug. I am really hoping to get MNI152 (because I also use fsl). Are MNI305 and MNI152 the same? How can I obtain MNI152 coordinates?
Best, Daniel
-- Yung-Jui "Daniel" Yang, PhD Postdoctoral Researcher Yale Child Study Center New Haven, CT (203) 737-5454
On 9/10/13 5:14 PM, "Douglas N Greve" <greve@nmr.mgh.harvard.edu mailto:greve@nmr.mgh.harvard.edu> wrote:
It is an estimate of Tal coords from the MNI305. See http://imaging.mrc-cbu.cam.ac.uk/imaging/MniTalairach If you want MNI305, run mri_surfcluster with --nofixmni doug On 09/10/2013 05:08 PM, Yang, Daniel wrote: Hi all, The output of mri_surfcluster --sum shows TalX TalY TalZ. I am wondering if they are based on the Talairach system or some sort of MNI-Talairach system. If the latter, can you tell me something more about it? Like a webpage that describes its relationship between the MNI152 or the Talairach system? I find it confusing because mri_surfcluster said: "INFO: fixing MNI talairach coordinates" Thanks! Daniel -- Yung-Jui "Daniel" Yang, PhD Postdoctoral Researcher Yale Child Study Center New Haven, CT (203) 737-5454 _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu <mailto:Freesurfer@nmr.mgh.harvard.edu> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer -- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu <mailto:greve@nmr.mgh.harvard.edu> Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edumailto:Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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