Analytics light and Transparent material problem

[Colin55]

Hi~
When I use analytics light and sss material together, strange things happen to the characters

But when I use primitive lights, or close the transmission channels, it goes back to normal

Why does this happen？ The file is attached.

[twik25]

I tried to open the C4D file to take a look, but I received the following warning "This document may have been created with an unauthorized version of Cinema 4D. For more information or to report software piracy, please visit: https://www.maxon.net/piracy"

[Colin55]

The "screen capture" files do not include all possible factors (the project files can only be opened by C4D users).
Some thoughts that could help:

1. When using Universal Material, transmission, when "enabled", is defaulted to a Specular mode
2. The asset seems to be a simplified character where maps separate shading parts, this is not ideal and may require the use of a composite / mix node setup or splitting geometry
3. Is the scene scale plausible?

No issue on Octane 2024 (Stable Release),
- the analytic light is the only light source,
- material is universal with transmission and SSS medium:
- PT kernel

universal-mtl-sss-transmission-analytic-light.jpeg

Yeah, I actually have a really, really big plane with texture emission material for the background, but why does scene scale affect analytic light ,not others?

[jayroth2020]

Analytic lights are not compatible with transparent materials, sadly.

[jayroth2020]

Yes, sorry, I was referring to analytic spot lights and fog. These elements are clipped by transparent surfaces.

[Colin55]

Project scale and asset-level scaling (not the whole project or "scene") do matter for several reasons and on different aspects.

• When it comes to light, Octane takes a relatively more physical approach, than let's say Cycles, where scale changes the "emission output" unless the corresponding checkboxes are enabled to keep it constant. This applies to any light in Octane.

• When it comes to shading, a wrong unit or inappropriately scaled asset will result in "inappropriate calculations" of refraction, SSS (radius is based on the scale), etc.

• Another reason at "kernel level" is Ray Epsilon, not much pertinent here but worth mentioning.

Ensuring the scale is appropriately set is one less aspect to worry about, one less thing to trouble solve in case of rendering issues.

Thank you! You're such a generous person. You're not stingy about sharing knowledge with others.