# Multivolume rendering

**URL:** <https://discourse.slicer.org/t/multivolume-rendering/42858>\
**Category:** Support\
**Tags:** volume-rendering\
**Created:** [May 10, 2025, 1:45am UTC](https://discourse.slicer.org/t/multivolume-rendering/42858 "2025-05-10T01:45:18Z")\
**Posts on this page:** 4\
**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:** [May 10, 2025, 1:45am UTC](https://discourse.slicer.org/t/multivolume-rendering/42858/1 "2025-05-10T01:45:18Z")

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I am testing multiple volume rendering for a visualization. When I turn on the 3rd volume, it doesn’t displayed, and I receive this message

```auto
Links failed: ERROR: Implementation limit of 16 active fragment shader samplers (e.g., maximum number of supported image units) exceeded, fragment shader uses 18 samplers
Shader failed to compile

```

These are very small volumes 178x314x221. Is there any way to mitigate this?

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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:** [May 10, 2025, 3:24am UTC](https://discourse.slicer.org/t/multivolume-rendering/42858/2 "2025-05-10T03:24:37Z")

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I don’t know for sure, but that sounds like a hardware limit that would be hard to workaround without rewriting the renderer.

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**Author:** ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter)\
**Post date:** [May 12, 2025, 9:49am UTC](https://discourse.slicer.org/t/multivolume-rendering/42858/3 "2025-05-12T09:49:33Z")

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I just managed to show three sample datasets with Multi-volume rendering:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/f/2fca39732a8cb85b6463890610d89a4db814e424.jpeg)

This computer has a 4090, But based on the message you posted this does not seem to be a hardware problem.

What Slicer version do you use?

Update: I just saw that the “regular” GPU Ray Casting now seems to support multiple volumes (the volumes are not just rendered on top of each other). I am surprised, because I try to follow updates about this, and we even talked about this at the PW in January and I wasn’t aware.

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<div class="post-metadata">

**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:** [May 12, 2025, 3:22pm UTC](https://discourse.slicer.org/t/multivolume-rendering/42858/4 "2025-05-12T15:22:14Z")

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This was on a M3 pro with a recent (within a few days of latest) preview version. I will give it a try with a windows box later.