Using Mediums with Materials

Any Octane material type that features a medium port or pin can be used to create sub-surface scattering with mediums: Diffuse, Specular and Universal.

DIFFUSE

The diffuse material will take more work to dial in your medium’s settings, as more energy is lost (absorbed) within the material, which will require you to increase power in the transmission texture slot to see the sub-surface scattering effect. Diffuse materials tend to work better with planar objects.
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SPECULAR

The Specular material is the most evident and easiest to control, as it light will pass through specular materials in the most efficient manner, losing very little of its energy. Specular materials can be the best way to show sub-surface scattering with thicker objects. For Random walk SSS, fake shadows will need to be enabled in order to see the effect, as random walk will only do indirect sampling in that case.

UNIVERSAL

The Universal material is the Octane über material, as it encompasses pins for every shading aspect supported by OctaneRender.

KERNELS FOR SSS

The Path Tracing and PMC kernels are best used as the Render Kernel for sub-surface scattering. You may need to increase the sample count depending on your scene. Note that doing so will increase render times.

SSS Tips
Properly constructed meshes are required to get the best results from SSS. Here are some considerations to keep in mind:
- Make sure your object is closed (watertight, no holes) or thick when using Mediums.
- Single-sided objects, mediums will not work.
- Keep the Material Reflection value low — if the reflection is high enough rays do not enter the object and are, instead, reflected back.
- Finally, the Absorption and Scatter phenomena coexist in nature. These two options work together for the most realistic results.