Hi Doug,
I am trying to convert MNI to RAS. I know the formula to convert from RAS to MNI is: MNI305RAS = TalXFM*Norig*inv(Torig)*[tkrR tkrA tkrS 1]' In theory, I should just be able to just invert this, but I am having difficulties because TalXFM is a non-square matrix and therefore not invertible. In addition, I tried using the moore-penrose pseudoinverse of the matrix but the values obtained do not match those in tkmedit. Do you have a formula for going from MNI to RAS or any advice about how would go about doing this?
Thank you, Jared
Why isn't it square? Did you add a 4th row of [0 0 0 1]?
On Jul 23, 2012, at 5:28 PM, Jared Deck jmd33@geneseo.edu wrote:
Hi Doug,
I am trying to convert MNI to RAS. I know the formula to convert from RAS to MNI is: MNI305RAS = TalXFM*Norig*inv(Torig)*[tkrR tkrA tkrS 1]' In theory, I should just be able to just invert this, but I am having difficulties because TalXFM is a non-square matrix and therefore not invertible. In addition, I tried using the moore-penrose pseudoinverse of the matrix but the values obtained do not match those in tkmedit. Do you have a formula for going from MNI to RAS or any advice about how would go about doing this?
Thank you, Jared _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
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Bruce Fischl -
Jared Deck