Hi Lisa,
this is an affine transformation. Usually there is a 4th row containing 0 0 0 1
A point at position x,y,z is mapped to the target location via
M * (x,y,z,1)^t where M is the 4x4 matrix and (x,y,z,1)^T is the column vector of the coordinates of the point with a 1 in the 4th row.
The top left 3x3 sub matrix of M is a linear transformation (rotation,scaling, sheering combined) and the last column is the translation.
Take a look here to review http://en.wikipedia.org/wiki/Transformation_matrix
So you cannot directly extract scaling factors and rotation from the 3x3 submatrix.
Best, Martin
On Thu, 2010-11-04 at 10:51 -0700, Lisa F. Akiyama wrote:
Hello,
Could someone inform me what each value of the 3x4 talairach transformation matrix signifies (e.g. translation, rotation in specific directions)? Here's an example of an talairach.xfm output.
MNI Transform File % tkregister2 Transform_Type = Linear; Linear_Transform = 1.05550623 0.03465762 -0.08214028 -3.92954969 0.02312534 1.03939676 0.38879746 -13.37033176 0.00010875 -0.35171938 1.10944259 -10.23139286Thank you.
Best, Lisa ______________________________ Lisa F. Akiyama Research Study Assistant Institute for Learning & Brain Sciences (I-LABS) University of Washington
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On Tue, Nov 2, 2010 at 2:59 PM, Lisa F. Akiyama lrisa87@uw.edu wrote: Hello,
Are there any documentations on the details of the talairach_avi command and the 3x4 matrix (talairach.xfm) output? Thank you. Best, Lisa Akiyama ______________________________ Lisa F. Akiyama Research Study Assistant Institute for Learning & Brain Sciences (I-LABS) University of Washington P Please consider the environment before printing this e-mail.
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