# Registration nii volumes

**URL:** <https://discourse.slicer.org/t/registration-nii-volumes/8704>\
**Category:** Support\
**Tags:** registration\
**Created:** [October 8, 2019, 8:12am UTC](https://discourse.slicer.org/t/registration-nii-volumes/8704 "2019-10-08T08:12:31Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Alessandro\_Piol](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/alessandro_piol/32/4218_2.png) [@Alessandro\_Piol](https://discourse.slicer.org/u/Alessandro_Piol)\
**Post date:** [October 8, 2019, 8:12am UTC](https://discourse.slicer.org/t/registration-nii-volumes/8704/1 "2019-10-08T08:12:31Z")

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Good morning all,  
I cannot finalize a registration between two volumes, representing the same CT reconstruction (.nii). I have one volume smaller than the other, which is even not aligned. These are the steps I follow:

- I put the markers on the two volumes to identify common points;
- I create a Similarity transform based on the just created markers;
- I apply the transform to the volume I want to move (the smaller one);

The result is that the volume rotates in the right way, but it is not scaled (it is still with the same dimensions).

Is the correct way to do what I want to do?  
Thanks in advance.

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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 8, 2019, 11:53am UTC](https://discourse.slicer.org/t/registration-nii-volumes/8704/2 "2019-10-08T11:53:22Z")

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Which modules do you use for this?