# IJKtoRAS in 3d slicer vs nibabel

**URL:** <https://discourse.slicer.org/t/ijktoras-in-3d-slicer-vs-nibabel/33307>\
**Category:** Support\
**Created:** [December 9, 2023, 2:59am UTC](https://discourse.slicer.org/t/ijktoras-in-3d-slicer-vs-nibabel/33307 "2023-12-09T02:59:10Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Santiago\_Cutiller](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/santiago_cutiller/32/5909_2.png) [@Santiago\_Cutiller](https://discourse.slicer.org/u/Santiago_Cutiller)\
**Post date:** [December 9, 2023, 2:59am UTC](https://discourse.slicer.org/t/ijktoras-in-3d-slicer-vs-nibabel/33307/1 "2023-12-09T02:59:10Z")

</div>

Hello, I am working with nibabel and I have noticed that the affine matrix that I obtain with nibabel is different from the one shown by 3d slicer in the “Volumes” module.  
In this example I obtain this matrix with nibabel:

[[0.4670569 -0.04001786 -0.00583032]  
[0.03880422 0.46219775 -0.07265816]  
[0.01120476 0.06741843 0.49465886]]

and with 3d slicer:

0.996282 -0.0853623 -0.0116606  
0.0827735 0.985917 -0.145316  
0.0239009 0.143811 0.989317

Why does this happen?