PBM Channels

The 3DCoat render system supports an advanced physically based material (PBR/PBM) model. It includes not only standard channels but also specialized effects to create the most realistic surfaces possible.

Below is a detailed description of each channel and its impact on the material’s appearance, based on the internal shader architecture.

1. Base Channels

• AlbedoColor (Albedo / Base Color)
  The main color of the surface. For dielectrics (non-metals), this is their own color. For metals, it’s their reflection color.
• Opacity
  Determines how opaque a pixel is. Usually used for “CutOut” transparency (leaves, meshes), hiding geometry where the value is low.
• Emissive
  Adds self-illumination to the material. The surface will be bright even in complete darkness and can cast light on neighboring objects (via global illumination).
• TSNormal (Tangent Space Normal)
  A normal map that defines fine surface relief without altering the geometry itself.
• AmbientOcclusion
  Micro-shadowing in recesses. Darkens areas that are hard for diffuse light to reach, emphasizing the volume of the relief.
• Mask
  A general technical channel that can be used for layer blending logic or creating custom effects.

2. Specular & Metalness

• Metalness
  Determines whether a material is a metal.
• 0 (Dielectric): Reflects only 4% of light at a direct angle (depends on IOR), albedo acts as the surface color.
• 1 (Metal): Albedo becomes the reflection color (e.g., yellow gold), and the diffuse color disappears.
• Roughness / Gloss
  Gloss = 1.0 - Roughness. Determines the “polish” of the surface. High Gloss gives sharp, mirror-like reflections, while high Roughness blurs reflections, making the surface matte.
• IOR (Index of Refraction)
  Determines the strength of the base reflection (F0) for non-metals. For example, water has an IOR ~1.33, glass ~1.5. Affects how strongly a surface reflects light when viewed at a direct angle.
• ReflectionColor
  Additional color control for reflection. Usually, reflection for non-metals is colorless, but this channel allows you to forcefully change its tint (e.g., for stylized materials).
• SpecularEdgePower
  Controls the Fresnel effect (how strongly a material reflects light when viewed at a grazing angle). Allows you to enhance or weaken highlights on the edges of an object.
• FlatSpecular
  Allows you to “flatten” reflections, ignoring fine irregularities from the normal map. Useful for stylization or avoiding “noisy” highlights on complex details.

3. Refraction / Glass

• Refraction
  Unlike Opacity (which simply “cuts” a hole), this is physical material transparency (like glass or water). Light passes through the surface and refracts. The higher the value, the more transparent the material.
• RefractionBlur
  Frosted glass. Blurs the background visible through a transparent object. Often linked to regular Roughness but allows controlling background blur separately.
• RefractionMetalness
  Allows creating translucent metals (like thin gold foil or metallized films) while retaining transparency.
• RefractionChromatic (Chromatic Aberration)
  Separates refracted light into a spectrum (like a prism), creating colored halos on the edges of thick glass.

4. SubSurface Scattering (SSS & Volume)

Used for translucent materials (skin, wax, milk, plastic, jade).

• SubSurface / Volume
  Determines how deep light penetrates into the material. This makes shadows softer and translucent edges brighter.
• SubSurfaceColor
  The color of the light that scatters beneath the surface. For example, for human skin, AlbedoColor would be flesh-toned, while SubSurfaceColor would be red (due to blood under the skin).

5. Special Surface Effects

• Anisotropy
  Stretches the specular highlight in a specific direction. Characteristic of brushed metal (pots), hair, or silk.
• Iridescence
  Thin film interference effect. Creates rainbow shifting colors depending on the viewing angle (like on soap bubbles, insect wings, or spilled gasoline).
• EffectNormal
  A color channel (vector direction) that defines the direction for stretching the anisotropic highlight and the direction for the iridescence gradient.
• ClearCoat
  Creates an additional transparent glossy layer on top of the existing material (like car paint or varnished wood). This layer has its own reflection, independent of the base material.
• ClearCoatGloss
  Determines how smooth the clear coat layer is.

6. Fabrics, Micro-relief and Fuzz

These channels are designed to simulate materials with complex microstructures on the surface (fabrics, dust).

• Velvet / Sheen
  Creates a soft highlight on the edges of an object. Characteristic of velvet, peach, suede. This is light reflecting from micro-fibers at grazing angles.
• SheenColor
  Tints the fabric highlight a specific color.
• Microprotrusions (Fuzz / Dust)
  Simulates the presence of microscopic particles (or dust) on the surface that scatter light differently than the main surface. Can make the material “dusty”.
• MicroprotrusionsGloss
  Controls how sharply these micro-fibers reflect light.
• MicroprotrusionsColor
  The color of the dust or fuzz resting on the material.