Hello,
I am working on an issue which is finding the voxel position before SPM realignment estimate&reslice based on the rigid-body transformation.
I've already calculated the rigid-body transformation matrices for all the time points according to the rp*.txt. The formula which I found was:
(y1,y2,y3,1)'=M*(x1,x2,x3,1)'
M- transformation matrix
x- voxel position in an image
y- voxel position in another space
First, I don't know if the x and y here are the vx or mm (we can read both voxel position information from the SPM Graphic).
Second, are there any assumption on this formula? Such as x and y space should have same voxel size or anything else which may affect this formula.
Third, if the y I compute out is the voxel position in the image before SPM (2dseq) or after?
Forth, how does the reslice affect the voxel position? I notise there is a voxel-to-world matrix, should I use that?
I am stucked here.
Thanks in advance.
Best Regards,
Yuan Wang
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