Author: rick reynolds (---.nimh.nih.gov)
Date: 03-16-09 11:02
Hi William,
Yes. The qoffset_{x,y,z} values are explicitly LR, PA, IS, as the
transformations always describe resulting coordinates in LPI (sign
and order) orientaion. The sign of those coordinates corresponds
to LPI being the negative directions.
This is much like Dicom images, which give coordinates in RAI,
regardless of the actual orientation of the data on disk. There,
RAI are the negative directions (2 of them opposite that of NIfTI).
These offset coordinates are applied after the transformation
matrix is applied, and so they must be LR, PA and IS, respectively.
The same applies for the sform matrix.
See the section on "ORIENTATION AND LOCATION IN SPACE" from the
nifti.h standard for details:
http://nifti.nimh.nih.gov/pub/dist/src/niftilib/nifti1.h
- rick
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