Sub-Surface Scattering

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B.Y.O.B.
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Re: Sub-Surface Scattering

Post by B.Y.O.B. » Wed Nov 04, 2020 3:54 pm

One more thing: I'd love to see a color input slot in the Material Shadow Color
This property is not texturable on the LuxCore side.

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MetinSeven
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Re: Sub-Surface Scattering

Post by MetinSeven » Wed Nov 04, 2020 3:58 pm

OK, no problem. It would just be slightly more convenient if you could plug in a color you're already using for other inputs.
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Sharlybg
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Re: Sub-Surface Scattering

Post by Sharlybg » Wed Nov 04, 2020 4:18 pm

Btw giving how easy it is to setup volume in other renderer i think we should make Luxcore implementation more convenient.
The current way is even too hard to setup for me considering how used i'am to luxcore it is definetly not user friendly.

Also it is almost impossible to get a nice result without shadow color set almost to white. As shadow color is not phisycally correct i think there should be something to improve. In average volume scatthering in lux is darker and slower to render.
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Re: Sub-Surface Scattering

Post by B.Y.O.B. » Wed Nov 04, 2020 4:42 pm

Sharlybg wrote:
Wed Nov 04, 2020 4:18 pm
Btw giving how easy it is to setup volume in other renderer i think we should make Luxcore implementation more convenient.
The current way is even too hard to setup for me considering how used i'am to luxcore it is definetly not user friendly.
Do you mean for volumes in general, or just for this specific SSS case?
I agree that getting SSS to look the way you want is right now very hard and should be improved. I think the best course of action would be to extend the disney material implementation with SSS support.

If you mean that volume settings in general should be improved, you will need to describe in more detail what you think should be changed (in a new thread or github issue).

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Sharlybg
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Re: Sub-Surface Scattering

Post by Sharlybg » Wed Nov 04, 2020 4:55 pm

Do you mean for volumes in general, or just for this specific SSS case?
I agree that getting SSS to look the way you want is right now very hard and should be improved. I think the best course of action would be to extend the disney material implementation with SSS support.
Yes this.

But also this.
If you mean that volume settings in general should be improved, you will need to describe in more detail what you think should be changed (in a new thread or github issue).
But here it is more a performance request and more related to Smoke volume compared to other renderer.
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Re: Sub-Surface Scattering

Post by MetinSeven » Wed Nov 04, 2020 5:14 pm

B.Y.O.B. wrote:
Wed Nov 04, 2020 4:42 pm
I agree that getting SSS to look the way you want is right now very hard and should be improved. I think the best course of action would be to extend the disney material implementation with SSS support.
That'd be great, thanks!
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Re: Sub-Surface Scattering

Post by CodeHD » Wed Nov 04, 2020 5:16 pm

MetinSeven wrote:
Wed Nov 04, 2020 3:28 pm
I was thinking: how come in real life certain materials have a certain light, almost glowing SSS, as if the light is perfectly scattered inside the volume without the surface or volume significantly decreasing the light strength. As BYOB mentioned, using a Glossy Translucent material darkens the SSS. Isn't there a scientifically viable way to retain light strength inside a volume in a more effective, but still physically correct way, like some real-life plastics seem to almost emit light due to SSS?
Two things come to my mind immediately:
1) You have to consider the geometry and homogeneity of the material. I know it from 3D-printed parts with "transparent" filaments that you will have scattering on the surface and from bubble inclusions at layer/line intersections, but the bulk material inside can be very clean and transparent.
2) Some materials exhibit fluorescence, which can result in a glowing appearance under the right lighting conditions.

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Re: Sub-Surface Scattering

Post by MetinSeven » Wed Nov 04, 2020 6:22 pm

Good points. Maybe a specialized fluorescent material would be a nice addition to LuxCore's material types?
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DionXein
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Re: Sub-Surface Scattering

Post by DionXein » Wed Nov 04, 2020 7:14 pm

MetinSeven wrote:
Wed Nov 04, 2020 3:28 pm
Isn't there a scientifically viable way to retain light strength inside a volume in a more effective, but still physically correct way, like some real-life plastics seem to almost emit light due to SSS?
You can try to lightin some parts inside mesh, using emission socket.
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Flourest.png
light_inside.jpg

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Re: Sub-Surface Scattering

Post by CodeHD » Wed Nov 04, 2020 7:14 pm

For now, that would loop back to Dade's earlier tip: add some emission to emulate the behaviour. Depending on the absoprtion depth, I could imagine you wil be better off with emission on the surface material rather than the volume though...

Edit: I worte this at the same time as DionXein, so just to clarify: Not a contradiction to what he shows, just a guess for different scenarios.

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