Unconventional SSS on GPU trough the Ubershader !

Here i have an SSS-GPU solution trough the Ubershader Transmission depth, it is real depth transmittance.

I came across this thinking about a thing: Basically flesh is a refractive water mass going insanely high with the rougheness value cause of the cells and losses energy based on depth, so i tried exactly that.
Depending on the medium (wax,etc…) you can raise the IOR and change the transmission depth.

Simply get the Ubershader and set the settings you see in this screenshot, then tweak around with the transmittance DEPTH value! Also don’t forget that you have to have at least 4x bounces on in the ray settings for good results.
I think this is quasiSSS, and very fast. No CPU separate rendering anymore, etc.

Have fun!


Interesting application of the shader! This is the kind of experimentation I like to see. I’ll have to give it a try, I’m interested in seeing how it handles front scattering and whatnot.

Here i have another test. Looks like its working pretty well :smiley:
Also this was a FAST test, don’t judge my melon mesh LOL :stuck_out_tongue:

The seeds are actually real 3d mesh seeds in the melon volume, getting more and more blurry behind.
The same gradient that is the texture controls also the opacity of the refraction! So the green margin is gradually completely opaque for any transmission. Also the butter has the SSS also.

Although this is a 2x bounce render only, 4x or even better 8x is great. The more secondary bounces the better, especially in the transmission setting!
Also, it is only beginning to look real at at least 256samples, but 512 is best.



OK, a new test.
As long as you stay with the HDRI environment (like above, most cases) and depend only on light transport trough HDRI everything is ok.

BUT (see below) the moment you DEPEND on caustics (no HDRI map), you are screwed, also no more transmittance setting (DEPTH has to be off=0!) :-D, meaning it gets VERY expensive.
This is also the case in many other scenarios (not related to this post, but caustics), but here more than ever, because EVERY “SSS” scattering depends now on the caustics, it will converge noisy, cause it will depend SOLELY on brute forcing the caustics in the medium.

I though about it, solving it trough a proximity setup ? (modified AO node?) I am not a node guru :-P.
Of course you can fake it with selecting specific mesh faces to be emissive, but a automatic node construct would be great. On/Off=easy :slight_smile:

What would be required is to transfer somehow received light to the Ubershader emission shader so no caustics are involved AND there is fast retransport.

Here the exact INVERSE case is happening, instead of absorbtion (transmission depth value), there has to be emission (emission trough depth ?) hmm…! Cause absorbtion requires caustics. :stuck_out_tongue:

If you can solve the light retransmission with a node setup, you would have to win the nobel prize! :smiley:

However, MANY, and great thanks for the Ubershader, you are a genius. :wink: It is a science in itself :smiley: