Thank you Doug,
What I have is MEG data in RAS coordinates and I want to convert it to Talairach.
So I do not have a talairach.xfm file.So how does one do it. will the m file you gave work without the .xfm file
Ajay
Doug Greve wrote:
If you have the RAS in a vector: v = [R A S 1]';
And the talairach.xfm matrix X, then MNI talairach cooridnates are:
vMNI = X*v;
These can be computed to something closer to true talairach coords using the attached mfile, originally from Matthew Brett.
doug
Ajay Pillai wrote:
Hello all,
Does any one have a matlab routine to convert given coordinates from RAS to talarach space.
If not atleas give an indication of how to do it?
Ajay _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
function outpoints = mni2tal(inpoints) % Converts coordinates from MNI brain to best guess % for equivalent Talairach coordinates % FORMAT outpoints = mni2tal(inpoints) % Where inpoints is N by 3 or 3 by N matrix of coordinates % (N being the number of points) % outpoints is the coordinate matrix with Talairach points % Matthew Brett 10/8/99
dimdim = find(size(inpoints) == 3); if isempty(dimdim) error('input must be a N by 3 or 3 by N matrix') end if dimdim == 2 inpoints = inpoints'; %' end
% Transformation matrices, different zooms above/below AC upT = spm_matrix([0 0 0 0.05 0 0 0.99 0.97 0.92]); downT = spm_matrix([0 0 0 0.05 0 0 0.99 0.97 0.84]);
tmp = inpoints(3,:)<0; % 1 if below AC inpoints = [inpoints; ones(1, size(inpoints, 2))]; inpoints(:, tmp) = downT * inpoints(:, tmp); inpoints(:, ~tmp) = upT * inpoints(:, ~tmp); outpoints = inpoints(1:3, :); if dimdim == 2 outpoints = outpoints'; %' end