# what is denoted by sitk.GetDirection()

**URL:** <https://discourse.itk.org/t/what-is-denoted-by-sitk-getdirection/3162>\
**Category:** Uncategorized\
**Tags:** mri, simpleitk, python\
**Created:** [June 10, 2020, 4:42am UTC](https://discourse.itk.org/t/what-is-denoted-by-sitk-getdirection/3162 "2020-06-10T04:42:19Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![prms](https://discourse.itk.org/user_avatar/discourse.itk.org/prms/32/1526_2.png) [@prms](https://discourse.itk.org/u/prms)\
**Post date:** [June 10, 2020, 4:42am UTC](https://discourse.itk.org/t/what-is-denoted-by-sitk-getdirection/3162/1 "2020-06-10T04:42:19Z")

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I want to understand the interpretation of the array returned by GetDirection in case of MRI image.  
(-0.9998157207129488,  
0.019196994953562158,  
0.0,  
-0.019196994953562158,  
-0.9998157207129488,  
0.0,  
0.0,  
0.0,  
1.0)

Can someone please help me understand this?

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**Author:** ![zivy](https://discourse.itk.org/user_avatar/discourse.itk.org/zivy/32/1726_2.png) [@zivy](https://discourse.itk.org/u/zivy)\
**Post date:** [June 10, 2020, 12:53pm UTC](https://discourse.itk.org/t/what-is-denoted-by-sitk-getdirection/3162/2 "2020-06-10T12:53:28Z")

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Hello @prms,  
The direction, often referred to as direction cosine matrix, is the direction of the image axis in row major order. In ITK/SimpleITK the axes are not necessarily orthonormal (identity matrix) which is the case with your data. This has to do with the fundamental idea in ITK/SimpleITK that an image is a spatial object. More on this in the [SimpleITK fundamental concepts](https://simpleitk.readthedocs.io/en/master/fundamentalConcepts.html) page.

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<div class="post-metadata">

**Author:** ![prms](https://discourse.itk.org/user_avatar/discourse.itk.org/prms/32/1526_2.png) [@prms](https://discourse.itk.org/u/prms)\
**Post date:** [June 13, 2020, 11:44am UTC](https://discourse.itk.org/t/what-is-denoted-by-sitk-getdirection/3162/3 "2020-06-13T11:44:06Z")

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thanks a lot 🙂