# Coordinate System and Registration Transform Results

**URL:** https://discourse.itk.org/t/coordinate-system-and-registration-transform-results/5718
**Category:** Algorithms
**Tags:** registration, simpleitk
**Created:** [February 17, 2023, 9:19pm UTC](https://discourse.itk.org/t/coordinate-system-and-registration-transform-results/5718 "2023-02-17T21:19:28Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![elapins](https://discourse.itk.org/letter_avatar_proxy/v4/letter/e/96bed5/32.png) [@elapins](https://discourse.itk.org/u/elapins)
#### Post date: [February 17, 2023, 9:19pm UTC](https://discourse.itk.org/t/coordinate-system-and-registration-transform-results/5718/1 "2023-02-17T21:19:28Z")

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When I print the parameters for a certain image registration, what point is this translating?? the top left? or the center? I understand that the resulting transform transforms the fixed image to the moving, but what exact point is it transforming??

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### Author: ![zivy](https://discourse.itk.org/user_avatar/discourse.itk.org/zivy/32/1726_2.png) [@zivy](https://discourse.itk.org/u/zivy)
#### Post date: [February 17, 2023, 10:42pm UTC](https://discourse.itk.org/t/coordinate-system-and-registration-transform-results/5718/2 "2023-02-17T22:42:32Z")

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Hello @elapins,

You’ve been busy posting questions 😉 .

The transformations map all points, not a specific one. For more details see the transformation notebook referenced in [your other post](https://discourse.itk.org/t/affine-transform-offset-vs-fixed-center/5721/2).

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### Author: ![elapins](https://discourse.itk.org/letter_avatar_proxy/v4/letter/e/96bed5/32.png) [@elapins](https://discourse.itk.org/u/elapins)
#### Post date: [February 18, 2023, 4:13pm UTC](https://discourse.itk.org/t/coordinate-system-and-registration-transform-results/5718/3 "2023-02-18T16:13:56Z")

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Why does it output one value then? Because in an affine transformation, if there is shearing, not all points are going to move the same amount? So how can I query specific points (like the center of the moving image)?

thank you!!!

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### Author: ![dzenanz](https://discourse.itk.org/user_avatar/discourse.itk.org/dzenanz/32/1093_2.png) [@dzenanz](https://discourse.itk.org/u/dzenanz)
#### Post date: [February 20, 2023, 2:02pm UTC](https://discourse.itk.org/t/coordinate-system-and-registration-transform-results/5718/4 "2023-02-20T14:02:56Z")

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Each ITK transform class has a [`TransformPoint()`](https://itk.org/Doxygen/html/classitk_1_1Transform.html#a76d429aaf8c0b0dcb251b69d7b593fb2) method.