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by dualogy 5121 days ago
Also I'm wondering about the lighting. Some folks on Twitter called it dynamic Global Illumination but here they just call it indirect lighting. I wonder -- are they still using an ambient light? More specifically, what's their GI algorithm? Might be something like the voxel approach sported by @icare3D but then it seems that one's just barely interactive, not as "real-time" as this stuff -- or well it might be on a GTX680 with a really-lo-res voxelization.
4 comments
photon137 5121 days ago
Voxels would be too heavy. I have worked with volume rendering before and it's way too expensive to do it at this scale (although their scene with the light passing through the volumetric smoke column kind-of defied this).

Some real-time version of PRT? "RTRT"?

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dualogy 5120 days ago
Turns out it IS voxels! https://twitter.com/Icare3D/status/211404654062481408

(Of course the (fairly lo-res compared to your screen) voxelized geometry representation is not rendered directly to screen ala Atomontage or Gigavoxels -- the the GI is based on RT scene voxelization and approximate cone-tracing.)

Well that's awesome because at least there's (A) a paper for this (grokking it is another matter) and (B) seems like it runs really smoothly on next-gen GPUs!

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photon137 5120 days ago
lo-res being the key :) I can see how the voxel representation would be computed and made resident in GPU memory. What's amazing to me, that such a highly branched computation algorithm is now possible in real-time on a GPU! (we had branching available since SM 3.0 - but was "not recommended")
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SeoxyS 5120 days ago
The physical renderer in Cinema 4D is pretty fantastic, and calls it Indirect Illumination. It's pretty crazy slow at rendering this stuff. I've had 6h+ renders, per frame.
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TrevorJ 5120 days ago
In some cases, it involves calculating the angle and falloff of the original light, and placing extra lights at the right angles to simulate the bounce light.
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knghtwhosaysni 5120 days ago
I'm not sure about UE4, but Geomeric's Enlighten tech was added to UE3 last year. It seems likely to me that it would be the same thing in 4.
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