# Fiducial Registration wizard

**URL:** <https://discourse.slicer.org/t/fiducial-registration-wizard/4038>\
**Category:** Support\
**Created:** [September 9, 2018, 11:24pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard/4038 "2018-09-09T23:24:39Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![tomas](https://avatars.discourse-cdn.com/v4/letter/t/439d5e/32.png) [@tomas](https://discourse.slicer.org/u/tomas)\
**Post date:** [September 9, 2018, 11:24pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard/4038/1 "2018-09-09T23:24:39Z")

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Operating system: Windows 10  
Slicer version: 4.9.0

Hi,

I have some query regarding “Fidutial Registration wizard”.

I am using the ‘fiducial registration wizard’ module transform type “rigid” and “Similarity" Registration for my master thesis. I need some extra information about it:

1. Is the registration algorithm ICP method? or what is the mathematical model?
2. How can I quantify or compare the performance of registration by this module?
3. Does exist a way to calculate an error after the registration (for qualitative assessment and visualization options)?

Thanks  
Tomas

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**Author:** ![Andinet\_Enquobahrie](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/andinet_enquobahrie/32/75_2.png) [@Andinet\_Enquobahrie](https://discourse.slicer.org/u/Andinet_Enquobahrie)\
**Post date:** [September 10, 2018, 10:10am UTC](https://discourse.slicer.org/t/fiducial-registration-wizard/4038/2 "2018-09-10T10:10:57Z")

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Hi Thomas,

I am assuming you are referring to the the Fiducial Registration Module in SlicerIGT.

> 1. Is the registration algorithm ICP method? or what is the mathematical model?

This module uses [vtkIterativeClosestPointTransform](https://www.vtk.org/doc/nightly/html/classvtkIterativeClosestPointTransform.html#details)

> <https://github.com/SlicerIGT/SlicerIGT/blob/master/FiducialRegistrationWizard/Logic/vtkPointMatcher.cxx#L369>

> 1. How can I quantify or compare the performance of registration by this module?

The module returns RMS error.

1. Does exist a way to calculate an error after the registration (for qualitative assessment and visualization options)?

You can use [Checkerboard](https://www.slicer.org/wiki/Documentation/Nightly/Modules/CheckerBoardFilter) or subtract image modules to evaluate the registration visually.

HTH,  
Andinet

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**Author:** ![tomas](https://avatars.discourse-cdn.com/v4/letter/t/439d5e/32.png) [@tomas](https://discourse.slicer.org/u/tomas)\
**Post date:** [September 11, 2018, 5:03pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard/4038/3 "2018-09-11T17:03:07Z")

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Thank you very much.

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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:** [September 11, 2018, 6:28pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard/4038/4 "2018-09-11T18:28:59Z")

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Note that ICP is only used as an optional pre-processing step for automatic matching of out-of-order or missing points. Transform is computed using vtkLandmarkTransform class:

> <https://github.com/SlicerIGT/SlicerIGT/blob/master/FiducialRegistrationWizard/Logic/vtkSlicerFiducialRegistrationWizardLogic.cxx#L360>

vtkLandmarkTransform class implements Horn’s method:

> <https://github.com/Kitware/VTK/blob/master/Common/Transforms/vtkLandmarkTransform.cxx#L79-L82>

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**Author:** ![tomas](https://avatars.discourse-cdn.com/v4/letter/t/439d5e/32.png) [@tomas](https://discourse.slicer.org/u/tomas)\
**Post date:** [September 11, 2018, 9:08pm UTC](https://discourse.slicer.org/t/fiducial-registration-wizard/4038/5 "2018-09-11T21:08:01Z")

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Thank you very much.