# Adjusting Opacity of Volume Rendering to Visualize Segmented Lesions

**URL:** <https://discourse.slicer.org/t/adjusting-opacity-of-volume-rendering-to-visualize-segmented-lesions/30056>\
**Category:** Support\
**Tags:** segmentation, volume-rendering\
**Created:** [June 15, 2023, 6:27pm UTC](https://discourse.slicer.org/t/adjusting-opacity-of-volume-rendering-to-visualize-segmented-lesions/30056 "2023-06-15T18:27:29Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![yanpfei](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/yanpfei/32/6954_2.png) [@yanpfei](https://discourse.slicer.org/u/yanpfei)\
**Post date:** [June 15, 2023, 6:27pm UTC](https://discourse.slicer.org/t/adjusting-opacity-of-volume-rendering-to-visualize-segmented-lesions/30056/1 "2023-06-15T18:27:30Z")

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I performed volume rendering on a volume from a CT scan.  
I segmented the lesions within the said volume. Now, I have displayed both parts of the content in a 3D window.  
However, the content of the volume rendering overlays the segmented content, preventing me from seeing the relative position of the segmented lesion with the head (as seen in Figure 1).

 ![Fig1](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/9/f/9fb65c95cd7e6e047bd6e8e6d914caaeb9b248fb.png)

I am wondering if there is a way to adjust the opacity of the entire volume rendering so that I can visualize the segmented content.  
I have been able to achieve this effect with other software, such as MRIcroGL (as shown in Figure 2).

 ![Fig2](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/5/359e6722a51ba6c57e011dad71385963d013ba11.png)

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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:** [June 15, 2023, 8:05pm UTC](https://discourse.slicer.org/t/adjusting-opacity-of-volume-rendering-to-visualize-segmented-lesions/30056/2 "2023-06-15T20:05:17Z")

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> [@yanpfei](#):
>
> adjust the opacity of the entire volume rendering

Yes, you can via the Scalar Opacity maps. Please read the Volume Rendering section of the user documentation.

[https://slicer.readthedocs.io/en/latest/user\_guide/modules/volumerendering.html](https://slicer.readthedocs.io/en/latest/user_guide/modules/volumerendering.html)

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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:** [June 16, 2023, 1:55pm UTC](https://discourse.slicer.org/t/adjusting-opacity-of-volume-rendering-to-visualize-segmented-lesions/30056/3 "2023-06-16T13:55:27Z")

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Another approach is not to waste computational resources and limit your rendering options by using volume rendering for displaying the skin surface. Instead, you can [segment the skin surface using simple thresholding Warp solidify effect](https://lassoan.github.io/SlicerSegmentationRecipes/SkinSurface2/). You can then adjust the opacity of the skin surface segment to make the lesion in the brain visible.