# Warping transform from fiducial registration doesnt work with volumes

**URL:** <https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978>\
**Category:** Support\
**Created:** [April 18, 2023, 1:29am UTC](https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978 "2023-04-18T01:29:07Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [April 18, 2023, 1:29am UTC](https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978/1 "2023-04-18T01:29:07Z")

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I have created a warping transfrom from two landmark sets. The resultant transform can be successfully applied to a 3D model (see the screenshot, green model is under the resultant transform, and has a slight deformation compared to the skull its generated from).

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/b/c/bc9efb0a1e213ca4640aaa80f492631a56398fb9.jpeg)

However, when I put the volume under the same transform, I get strange deformation.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/1/a/1a85edecf5ea94dcc52d5087932dfa8e1bd72eee.jpeg)

How can we make the warping transform work with volumes? Performance is rather slow with 3D models with large number of vertices, so I am testing if volume rendering can be used instead.

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [April 18, 2023, 7:40pm UTC](https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978/2 "2023-04-18T19:40:10Z")

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Probably you are seeing this issue?

> [@Understanding CT Image spacing and Acquisition geometry regularization](https://discourse.slicer.org/t/understanding-ct-image-spacing-and-acquisition-geometry-regularization/19001/4):
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> This is probably correct because the volume rendering doesn’t take non-linear transforms like the acquisition correction into account. You can confirm this by making the slice views visible in the 3D view and they won’t match until you harden. It needs to be fixed at the VTK level, and we’ve discussed it but it hasn’t been done yet as far as I know. The volume rendering module should really generate a visible warning or error dialog when a volume with a nonlinear transform is selected. In an…

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [April 18, 2023, 8:35pm UTC](https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978/3 "2023-04-18T20:35:31Z")

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yes, apparently! (Slice view is correct). Meanwhile, is there a way to mitigate? Can I somehow use this transform to resample the image and render correctly?

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [April 18, 2023, 8:38pm UTC](https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978/4 "2023-04-18T20:38:39Z")

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Ok, it worked with resample. But it would be great if it can be done on the fly.

 ![Screen Shot 2023-04-18 at 1.38.15 PM](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/c/b/cbdc1aae2a311bf61f5b5de11a582862b6c4c614.jpeg)

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [April 18, 2023, 8:53pm UTC](https://discourse.slicer.org/t/warping-transform-from-fiducial-registration-doesnt-work-with-volumes/28978/5 "2023-04-18T20:53:31Z")

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Yes, agreed, we should perform the hardening step as part of the volume rendering displayable manager (one of the many improvements that are needed in the volume rendering module).