backlight marble - best process?

[Giuliovasa79]

Hi. I have to represent a backlit marble. i tried with sss material backlit by mesh light. But I'm not very convinced. Do you have any advice for me to get a better result?

[Micha]

A simple emitter material?

Or you use a standard marble based on diffuse and reflection and add an emissive layer with marble texture. You set the transparency of the emitter layer very high so that the standard marble below is visible. So,the material interact with the interior lights. Now you increase the emissive intensity like you want it. You should get a mix of back lighted and front lighted marble.

[konstantin_chaos]

Hi Giuliovasa79,

Micha is right - using a self illuminated material blended with some diffuse and reflections can work great in many cases.
It's also a pretty fast shader to render.
Unfortunately it'll not be easy to have varying backlight light intensity (based on light sources behind the mesh).
The self-illumination color or texture will be the only thing controlling the effect.

As an alternative I'd suggest you do the following:
- Create a regular V-Ray material with the marble texture diffuse, secularity and bump
- Add a Translucency attribute to the material (making it a two sided material)
- Remove the backsides of the marble tiles / patches since the translucency works best with single-sided surfaces. Alternatively, you can also place the lights inside the marble volume.
- Place lights behind and tweak the translucency material attribute parameter to get the effect you're after
This setup is also pretty fast to render.

And naturally using the SSS material is the most accurate option.
It'll be slower to render and will require more tweaking but can also work very well.

Konstantin