# 3D Rigid Registraion

**URL:** <https://discourse.slicer.org/t/3d-rigid-registraion/2441>\
**Category:** Support\
**Created:** [March 27, 2018, 5:19pm UTC](https://discourse.slicer.org/t/3d-rigid-registraion/2441 "2018-03-27T17:19:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![tyeung0217](https://avatars.discourse-cdn.com/v4/letter/t/5daacb/32.png) [@tyeung0217](https://discourse.slicer.org/u/tyeung0217)\
**Post date:** [March 27, 2018, 5:19pm UTC](https://discourse.slicer.org/t/3d-rigid-registraion/2441/1 "2018-03-27T17:19:03Z")

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Problem report for Slicer 4.8.0 win-amd64: [please describe expected and actual behavior]

Hi,

I’m registering two identical sets of images using the Genera Registration function and doing a rigid transformation. I’m surprised to see that there is non-zero translation and rotation transform being generated by the software. Since the two sets are identical, I don’t expect to see any transformation.

Can you comment if this is a bug?

Timothy

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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:** [March 28, 2018, 9:56pm UTC](https://discourse.slicer.org/t/3d-rigid-registraion/2441/2 "2018-03-28T21:56:10Z")

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Non-linear optimizers used in registration methods usually explore the parameter space around the initial value and may stuck in a local optimum.

This is an inherent limitation of registration methods, but also an indication that your choice of optimization parameters or similarity metric could be improved.