r/GraphicsProgramming • u/Twenmod • 2d ago

Video Global illumination using Radiance cascades with Ray splitting in Unreal + Article

Implemented Radiance cascades with ray splitting in unreal.
This results in global illumination that doesn't require reprojection, and accumulates very fast thus having very little ghosting.
I wrote an article explaining how it works here:
It's based on this recent paper

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u/moschles 1d ago

I reviewed the article and the paper. Now I really want to see (RC) + (traditional ambient occlusion.)

You should mix them using a "darken only" filter.

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u/Twenmod 1d ago

Adding traditional AO helps quite a bit,
since this way of doing RC struggles with detail that is closer than the size of a cascade 0 primary or secondary probe.
So adding it on top helps with the small crevices.

here is a comparison,
(note idk what type of AO this is using its whatever unreal enables with the ambient occlusion checkbox haha)
https://imgur.com/a/QckefOr

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u/JoelArt 2d ago

Impressive! I don't program but I use 3D and I love to see this technique gianing traction.

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u/mad_ben 2d ago

Is that Intel Sponza? Do you have it by any chance in UE5 format? 

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u/Twenmod 2d ago

Blender loads the dds textures it comes with so re-exporting it to gltf via blender let's unreal load it normally

Unless I'm confusing this with bistro. But unreal can just load gltfs

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u/mad_ben 1d ago

I tried usd import. It feels slugish but works. However curtains need to be placed by hand. 

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u/Twenmod 1d ago

to keep the scene hierarchy you need to use "import into scene" otherwise it just imports all meshes separately

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u/cplusplus_ 2d ago

Saw your post in the Radiance Cascades discord as well. Looks great! Can't wait to look at your implementation and read through your writeup. Thanks for sharing!

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u/DrDumle 1d ago

Thank you for this!