Hi, I found out something that I do not understand when I was trying to create rotation matrix from scratch. I have used two methods and hope they will give me the same results.
1st method---form matrix from cross product as described in http://nifti.nimh.nih.gov/nifti-1/documentation/nifti1fields/nifti1fields_pages/quatern.html for example: -0.9994 0 0.0343 0.0153 -0.8953 0.4451 0.0307 0.4454 0.8948 I use formed rotation matrix * D (voxel size) --- I got exactly same affine matrix (1:3) as the one in nifti header. However, I tried another method since I would like to use normal vector if there is no row and col vector directly available in DICOM header. 2nd method --- form matrix from vox2ras_rsolveAA.m I got the matrix has the wrong signs although the numbers are exactly same. It cannot be simply apply some (making sensed) unity matrix for the correction (I have already correct normal vector for the sake of the requirement in 1st method ---- reverse the sign for the first 2 row in normal vector, if I do not correct it, the matrix is still not same). For example: 0.9994 -0.0000 0.0343 -0.0153 -0.8953 0.4451 -0.0307 0.4454 0.8948 I was wondering if you would know the reason for it. Thanks, Jun _______________________________________________ Freesurfer mailing list [email protected] https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
