# SimpleITK Direction Matrix Behavior

**URL:** <https://discourse.slicer.org/t/simpleitk-direction-matrix-behavior/42094>\
**Category:** Development\
**Tags:** itk\
**Created:** [March 12, 2025, 4:43pm UTC](https://discourse.slicer.org/t/simpleitk-direction-matrix-behavior/42094 "2025-03-12T16:43:13Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ColbyCoffman](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@ColbyCoffman](https://discourse.slicer.org/u/ColbyCoffman)\
**Post date:** [March 12, 2025, 4:43pm UTC](https://discourse.slicer.org/t/simpleitk-direction-matrix-behavior/42094/1 "2025-03-12T16:43:13Z")

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Hello, I am having trouble understanding the behavior of the calculation of SimpleITK’s direction matrix. I sort a series in increasing z value based on ImagePositionPatient, but when i pass those files into ImageSeriesReader to create an Image, the direction matrix is (1,0,0,0,1,0,0,0,-1), which does not make sense to me. I am new working in this field, so any help would be appreciated.

Best,  
Colby