I started working through the Advanced Material Techniques Inside of Octane Training from Curse Studios and thought I’d share the notes I've taken so far. The training series is excellent and I highly recommend purchasing it. The instructor has a sense of humor and is excited about the content, making it easy to stay awake.
These notes aren't really meant to be comprehensive, they're more of a cheat sheet that I had in a text file off to the side while creating the materials on the elephants. The training series is broken up into 3 parts (Basic, Advanced, Project-Based). Below are the notes from Part 1.
Part 1: Basic Materials
Materials are split into 3 types (Diffuse, Glossy, Specular) and can be mixed together using an OctaneMix material to create more advanced effects.
Diffuse materials are used for surfaces that absorb light, like cloth. They’re not used as often as glossy materials because almost everything has some kind of specular reflection. However, Diffuse materials have an emission channel that allows you to use the material as a light source.
Glossy materials are used for…well, making glossy materials.
Specular materials are used for transparent objects like glass, liquids, and subsurface scattering.
Index of Refraction plays a big role in defining the look of materials.
Common glossy materials have an IOR between 1.3 and 2
Liquids range between 1.33 - 1.55
Metals range between 3-8 (however, there are many exceptions)
IOR for Water is 1.33
IOR for Plastics is 1.5
IOR for Glass is 1.6
IOR for Ceramic is 1.8
IOR for Diamonds is 2.417
Here’s an IOR chart online that’s meant for use in 3D applications:
When creating materials like gold or silver, start with a higher Index (around 6-8), turn Diffuse down to 15% black, and blend in the color of the metal using the Specular channel. Adjust IOR value depending on type of metal.
An alternative method is to lower the Index to around 3 and blend the color using the Diffuse and Specular channels together.
The transmission channel can be used to mix color into Specular materials. Simulate transparent plastics by adding Roughness. However, to create more advance liquid effects like orange juice, you’d need to use subsurface scattering.
Subsurface Scattering setup (in Specular Material):
• Add Scattering Medium shader to Medium channel
• Add an RGB Spectrum in the Absorption & Scattering channels (opposite hue to intended color, use color wheel for reference)
• Adjust scale to to control the effect
Here's a screenshot of the scene setup for the elephants. I'll need to come up with a better way to show off the materials next time.