# Scaling slider for LinearTransform

**URL:** <https://discourse.slicer.org/t/scaling-slider-for-lineartransform/17204>\
**Category:** Support\
**Created:** [April 20, 2021, 12:28pm UTC](https://discourse.slicer.org/t/scaling-slider-for-lineartransform/17204 "2021-04-20T12:28:49Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![FriedrichKretschmer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/friedrichkretschmer/32/10708_2.png) [@FriedrichKretschmer](https://discourse.slicer.org/u/FriedrichKretschmer)\
**Post date:** [April 20, 2021, 12:28pm UTC](https://discourse.slicer.org/t/scaling-slider-for-lineartransform/17204/1 "2021-04-20T12:28:49Z")

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Dear community,  
I am trying to register multiple 2D in-situ images to a 3D CT brain scan. For this purpose I do an initial coarse alignment by a manual linear transform. In a second step I apply landmark registration. I finally use the registered data to segment specific brain areas in the CT scan based on the overlayed in-situ data.

For the first manual alignment it would be very helpful to have an additional “Scaling” slider in the transform module. I currently manually alter the transform matrix for this purpose or use the image spacing parameters from the “volume” module.

I don’t see any technical reason why there should not be a scaling slider in the transformation module.  
What am I missing? Thank you in advance!  
Fritz

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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 20, 2021, 8:20pm UTC](https://discourse.slicer.org/t/scaling-slider-for-lineartransform/17204/2 "2021-04-20T20:20:59Z")

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There’s no technical reason except that typically only rigid registration is used for most volumetric registration (since they are already in calibrated units). But I suppose it wouldn’t hurt to have an advanced checkbox or something that exposes a scale slider. Could also add shears if people would find it useful.

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<div class="post-metadata">

**Author:** ![FriedrichKretschmer](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/friedrichkretschmer/32/10708_2.png) [@FriedrichKretschmer](https://discourse.slicer.org/u/FriedrichKretschmer)\
**Post date:** [April 21, 2021, 7:17am UTC](https://discourse.slicer.org/t/scaling-slider-for-lineartransform/17204/3 "2021-04-21T07:17:04Z")

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Thank you for the fast reply. This would be very helpful indeed!

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<div class="post-metadata">

**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 21, 2021, 12:27pm UTC](https://discourse.slicer.org/t/scaling-slider-for-lineartransform/17204/4 "2021-04-21T12:27:40Z")

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I’m not sure if anyone has the time to add this, but you can file a feature request [on the issue tracker](https://github.com/Slicer/Slicer/issues) and anyone can vote for the feature using the 👍 emoji. This is an example of a good intermediate programming task that would be an excellent learning project for a new developer who wants to learn the C++ side of Slicer (adding this involves making changes to [the Transforms loadable module](https://github.com/Slicer/Slicer/tree/master/Modules/Loadable/Transforms)).

If you just want a more easy way to scale a transform to accelerate your work of course you can add a little script to implement the feature.