Some documentaiotn is here https://surfer.nmr.mgh.harvard.edu/fswiki/CoordinateSystems?action=AttachFil... The matrix below is the Mdc in the PDF. The first column is the direction of the columns (ie, as you go from column 1 to column 2). In your case, it is [.999 -.009 .030]' in RAS coordinates. This vector means that you will mostly move in the R direction, a little bit in the P (negative A) direction, and a little bit in the S direction. Because it is mostly R, R is the first letter in the orientation string. The next column is the row direction. Is is mostly in the A direction. The slice direction is mostly in the S direction. So this would be RAS orientation.
On 1/25/19 9:06 PM, Ritesh Mahajan wrote:
External Email - Use CautionHi Bruce, Thanks for your response.
It would be really helpful if you explain how does it interpret from matrix.
Thanks, Ritesh Mahajan
----- Original Message ----- From: "Greve, Douglas N.,Ph.D." DGREVE@mgh.harvard.edu To: "freesurfer" freesurfer@nmr.mgh.harvard.edu Sent: Friday, January 25, 2019 10:26:47 PM Subject: Re: [Freesurfer] Orientation by direction cosines
mri_info will do it. If you just want the orientation string, you can add --orientation. Or do you still want the interpretation of the matrix?
On 1/25/19 10:10 AM, Bruce Fischl wrote:
Hi Ritesh
I think that mri_info will try to figure this out and tell you (in the "Orientation" output).
cheers Bruce
On Fri, 25 Jan 2019, Ritesh Mahajan wrote:
External Email - Use CautionHello Team,
Can any one please explain how we come to know whether it is RAI or RAS or any other orientation through direction cosines:
Below is the direction cosine: I saw some non zero and negative values in non diagonal values of matrix. What does this signify ?
0.999377 0 -0.0352819 -0.00916448 0.965676 -0.259588 0.0340709 0.25975 0.965075
Suppose it is Head First Supine. Any help will be really appreciated.
Thanks, Ritesh Mahajan
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