# Fiducial registration wizard - rigid transform algorithm

**URL:** <https://discourse.slicer.org/t/fiducial-registration-wizard-rigid-transform-algorithm/24976>\
**Category:** Development\
**Created:** [August 29, 2022, 1:18pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard-rigid-transform-algorithm/24976 "2022-08-29T13:18:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![joanne40226](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/joanne40226/32/14681_2.png) [@joanne40226](https://discourse.slicer.org/u/joanne40226)\
**Post date:** [August 29, 2022, 1:18pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard-rigid-transform-algorithm/24976/1 "2022-08-29T13:18:34Z")

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Hi community, i am now wondering about the rigid transform in IGT - Fiducial registration wizard.  
I want to know about the algorithm or the minimal objective function of the rigid transform for landmarks.  
However, it did not made the button of source code.  
Therefore, i am wondering what the minimal objective function of the landmarks is.  
Thank you for your time!

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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:** [August 31, 2022, 3:49am UTC](https://discourse.slicer.org/t/fiducial-registration-wizard-rigid-transform-algorithm/24976/2 "2022-08-31T03:49:01Z")

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[Fiducial registration wizard module uses vtkLandmarkTransform](https://github.com/SlicerIGT/SlicerIGT/blob/d3fd2b26a4c10f6319aa8ae4173abc793c4113ce/FiducialRegistrationWizard/Logic/vtkSlicerFiducialRegistrationWizardLogic.cxx#L361-L363) class for rigid registration.

[vtkLandmarkTransform uses the Horn method](https://github.com/Kitware/VTK/blob/316670f66f2aa9f4732379790f280187f518e179/Common/Transforms/vtkLandmarkTransform.cxx#L79-L82).

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**Author:** ![joanne40226](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/joanne40226/32/14681_2.png) [@joanne40226](https://discourse.slicer.org/u/joanne40226)\
**Post date:** [August 31, 2022, 3:54am UTC](https://discourse.slicer.org/t/fiducial-registration-wizard-rigid-transform-algorithm/24976/3 "2022-08-31T03:54:24Z")

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@lassoan  
Thank you so much!