# Reorientate/Register/Align two segmentation models/STL Files

**URL:** <https://discourse.slicer.org/t/reorientate-register-align-two-segmentation-models-stl-files/18164>\
**Category:** Support\
**Tags:** registration, segmentation, stl\
**Created:** [June 16, 2021, 12:34pm UTC](https://discourse.slicer.org/t/reorientate-register-align-two-segmentation-models-stl-files/18164 "2021-06-16T12:34:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Solli](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@Solli](https://discourse.slicer.org/u/Solli)\
**Post date:** [June 16, 2021, 12:34pm UTC](https://discourse.slicer.org/t/reorientate-register-align-two-segmentation-models-stl-files/18164/1 "2021-06-16T12:34:34Z")

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Hello,  
I started working with slicer.  
I have two different CT Series from the skull. In both images i segmented the bones of the skull. Now i want to compare the model and calculate with the Module Segment comparison the Dice coefficient and the Hausdorff distance. The goal is to find out if the segmented skull of the second CT serie is smaller than the skull of the first serie and to compare with Dice the similarity between both skulls.  
Now the problem is that one model is at the top of the bos and one at the bottom and the orientation of the model at the top is not right(anterior and posterior is switched)

Has anyone an idea how i can solve this problem?  
I attached a foto of my problem.

Best regards Solveig

 ![grafik](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/0/10f0e7cecc77c81aecc1349579a67ca6de2ed48f.png)

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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:** [June 17, 2021, 3:32am UTC](https://discourse.slicer.org/t/reorientate-register-align-two-segmentation-models-stl-files/18164/2 "2021-06-17T03:32:04Z")

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Before you can compare the segmentations, you must align them. You can use registration methods described in the [documentation](https://slicer.readthedocs.io/en/latest/user_guide/registration.html). For example, registration using Fiducial registration wizard, optionally followed by Model registration should work.

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<div class="post-metadata">

**Author:** ![Solli](https://avatars.discourse-cdn.com/v4/letter/s/ecd19e/32.png) [@Solli](https://discourse.slicer.org/u/Solli)\
**Post date:** [June 17, 2021, 3:47pm UTC](https://discourse.slicer.org/t/reorientate-register-align-two-segmentation-models-stl-files/18164/3 "2021-06-17T15:47:48Z")

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Hey Andras,

Thank you so much!! It worked well with the Model Registration and after i used the Segment Comparison to compute the Dice coefficient and the Hausdorff distance !! 🙂  
Best Regards  
Solveig