# Which difference between Direction Matrices in vtkImageData and vtkMRMLScalarVolumeNode?

**URL:** <https://discourse.slicer.org/t/which-difference-between-direction-matrices-in-vtkimagedata-and-vtkmrmlscalarvolumenode/25760>\
**Category:** Support\
**Tags:** dicom, python\
**Created:** [October 18, 2022, 3:35pm UTC](https://discourse.slicer.org/t/which-difference-between-direction-matrices-in-vtkimagedata-and-vtkmrmlscalarvolumenode/25760 "2022-10-18T15:35:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Cailen](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cailen/32/16975_2.png) [@Cailen](https://discourse.slicer.org/u/Cailen)\
**Post date:** [October 18, 2022, 3:35pm UTC](https://discourse.slicer.org/t/which-difference-between-direction-matrices-in-vtkimagedata-and-vtkmrmlscalarvolumenode/25760/1 "2022-10-18T15:35:11Z")

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![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/c/b/cb414f92f347eed88eef91d6d0bce554358e9f4f.png)  
This behavior spoils the display of the results of my algorithms, because only from the VTK it is not clear where to get the same matrix as in the slicer

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [October 18, 2022, 4:07pm UTC](https://discourse.slicer.org/t/which-difference-between-direction-matrices-in-vtkimagedata-and-vtkmrmlscalarvolumenode/25760/2 "2022-10-18T16:07:11Z")

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vtkImageData did not store image directions for many years, so we had to store image geometry (origin, spacing, and axis directions) in the MRML node, and removed it from vtkImageData (vtkImageData origin is always set to 0,0,0 and direction is set to identity). Therefore, right now, you must get the image geometry information from the MRML node.

In the not too distant future (maybe within a year) we’ll update Slicer to store image geometry in the vtkImageData, which will make things simpler.