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Suppy Bird avatar image
Suppy Bird asked ·

Control SSS color along the brightness/darkness

How can I control SSS color ( or another color ) along brightness/darkness ? Example, I want the dark area more red, the middle area more yeallow, the brightness area more blue . But it's never work like I want. I think this is really important for advance control realism and need to be improve in the future. Maybe generate color follow some curve. Please send my request to developer. Thanks !

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Mads Drøschler avatar image
Mads Drøschler answered ·

Thought solution is to parse a custom AOV write AOV for a sequence that samples the depth as a float.
Then Read AOV back in and use as a mask for some post gradient blender. If that wont work.
Just map it through x and y screenspace.
Sure, you need a disk file mask, not as sexy, but it should give you complete control on the artistic side and bring in just 1 practical composit element.

I did spend some time on the case yesterday and was looking at ray direction, depths and camera positions and light source, so I rotate Ray distance by the angle between the camera and the light and create a pseudo Depth by stating certain things regarding the distance rays, I did not manage to get something that looked awesome I did get something semi working, so, deleted.

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Thanks so much for your try ! I'm so glad if you send this request to developers. ;)

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Suppy Bird avatar image
Suppy Bird answered ·

@Lee Griggs : Yes, your feeling is so good. That's SSS Randomwalk v2. Color is yeallow.

Base color : 40, 66, 100

SSS color : 36, 80, 100

SSS weight : 0,5 ( 50% )

@Mike Samoylov : Thanks but the result is not good. Seem like the red color still affect all the range of brightness, not just the dark part. Also the red color is not strong like I want.

I believe that Arnold need new features for that with some threshold/bias parameter to transform brightness data and then apply SSS color range along with it.


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Mike Samoylov avatar image
Mike Samoylov answered ·

You can use Utility shader with Lambert shade mode as input of Ramp shader. Then use Ramp shader as SSS color input.

Lambert mode give you brightness/darkness gradient.

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Lee Griggs answered ·

What are the Base Color and SSS Color doing?

Are you using Randomwalk v2?

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Suppy Bird avatar image
Suppy Bird answered ·

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Lee Griggs avatar image
Lee Griggs answered ·

Standard Surface has Base Color, Subsurface Color. You can also add color to the Subsurface Radius.

Can you show a photo or render of the effect/material that you are trying to achieve?

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