# How to hollow a Volume Render using a Segment instead of a Surface Cut?

**URL:** <https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462>\
**Category:** Support\
**Tags:** segmentation\
**Created:** [January 11, 2021, 8:33pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462 "2021-01-11T20:33:27Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![Biomodelos\_3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/biomodelos_3d/32/9452_2.png) [@Biomodelos\_3D](https://discourse.slicer.org/u/Biomodelos_3D)\
**Post date:** [January 11, 2021, 8:33pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/1 "2021-01-11T20:33:27Z")

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Operating system:W10  
Slicer version: 4.11.20  
Expected behavior: Hollow a Volume Render using a Segment  
Actual behavior: ?

Can a Volume Render be Masked by a 3D Segment instead of a Surface Cut?  
I assume it can be done, but can’t figure it how. In the attached image, I want to hollow the Volume Render with the blue Segment.

 ![Restar Segmento de Render Volumetrico](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/d/3d76c9d6e3da1e4498a404fc9951760ed2e7c271.jpeg)

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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:** [January 11, 2021, 8:37pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/2 "2021-01-11T20:37:36Z")

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Install the SegmentEditorExtraEffects and use either the MaskVolume (applies only the selected segment) or SplitVolume (creates new volumes for all segments in the segmentation) tools to create new volumes that contain only the region you are interested.

You can use the Volume Rendering on the newly derived volume.

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**Author:** ![Biomodelos\_3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/biomodelos_3d/32/9452_2.png) [@Biomodelos\_3D](https://discourse.slicer.org/u/Biomodelos_3D)\
**Post date:** [January 12, 2021, 2:27am UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/3 "2021-01-12T02:27:42Z")

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Thanks @muratmaga! that really helped!  
This **[link](https://youtu.be/oxR5Tt4f4nE)** is a short video of what I’ve got. Pretty much what I was looking for, but cavity interiors are stepped. Any solution to that?

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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:** [January 12, 2021, 4:21am UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/4 "2021-01-12T04:21:13Z")

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> [@Biomodelos\_3D](#):
>
> cavity interiors are stepped

I guess you try to remove the contrast agent from the vessels to make them transparent, so that you get an endovascular view.

The bad news that you cannot easily achieve this with masking, because you will have very high intensity voxels (remnants of the contrast agent or the walls/vessels) right next to very low intensity (blanked out voxels), which will be rendered with staircase artifacts. With some effort you could soften it (create a black-and-white volume, then soften the edges with Gaussian smoothing, then subtract it from the original volume), but you may end up with blurred walls.

The good news that you don’t need to rely on segmentation to render cardiac CT images in endocardial view. You just need to edit the volume rendering transfer functions to make contrast agent transparent.

Default CT Cardiac volume rendering preset:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/0/9/09a267c089f9d194d6706577febcc4a35a144bfc.jpeg)

With contrast agent (approximately 300-700HU) made transparent:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/d/5/d55bdc59c27bb0cef2d76691fa96aae55ebc0c2a.jpeg)

![SlicerCapture](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/8/3/83c274aad6a2323e3989ba2c06b4fdaebce6214a.gif)

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<div class="post-metadata">

**Author:** ![Biomodelos\_3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/biomodelos_3d/32/9452_2.png) [@Biomodelos\_3D](https://discourse.slicer.org/u/Biomodelos_3D)\
**Post date:** [January 12, 2021, 10:34pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/5 "2021-01-12T22:34:15Z")

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Cool! Much more fast and easy! Thanks @lassoan, that’s exactly what I was searching for!

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**Author:** ![Biomodelos\_3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/biomodelos_3d/32/9452_2.png) [@Biomodelos\_3D](https://discourse.slicer.org/u/Biomodelos_3D)\
**Post date:** [January 13, 2021, 3:51pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/6 "2021-01-13T15:51:57Z")

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About Volume Render, is there a way to save - load what you do with Volume Render Advanced controllers, so you can use your own presets in other studies?

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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:** [January 13, 2021, 6:57pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/7 "2021-01-13T18:57:06Z")

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You can save the volume rendering preset parameters and use it anywhere. Content of volume rendering preset file is described [here](https://slicer.readthedocs.io/en/latest/developer_guide/modules/volumerendering.html#format-of-volume-property-vp-file).

You can also load the saved .vp file into any Slicer scene and choose that in Volume rendering module / Inputs / Property.

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<div class="post-metadata">

**Author:** ![Biomodelos\_3D](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/biomodelos_3d/32/9452_2.png) [@Biomodelos\_3D](https://discourse.slicer.org/u/Biomodelos_3D)\
**Post date:** [January 16, 2021, 5:16pm UTC](https://discourse.slicer.org/t/how-to-hollow-a-volume-render-using-a-segment-instead-of-a-surface-cut/15462/8 "2021-01-16T17:16:08Z")

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> [@lassoan](#):
>
> You can also load the saved .vp file into any Slicer scene and choose that in Volume rendering module / Inputs / Property.

Thanks! very useful info!