Physically Based Materials
- PBR: surfaces approximate real-world light behavior; work equally well in all lighting environments; values less interdependent. References Karis "Real Shading in Unreal Engine 4", Burley (Disney), Lagarde, Hable.
- PBR attributes: Base Color, Roughness, Metallic, Specular; all 0–1.
- Base Color: color photographed with polarizing filter; measured tables (charcoal 0.02 … fresh snow 0.81; metals e.g. gold (1.000,0.766,0.336)).
- Roughness 0 = mirror, 1 = matte; roughness maps add variation; "The Specular input is not used for reflection/specularity maps or to add surface variation. These should be handled in the Roughness map."
- Metallic: treat as binary (0 or 1) for pure surfaces; intermediate only for hybrid (corroded, dusty); metallic masks should be black/white.
- Specular default 0.5 ≈ 4% specular reflection, accurate for vast majority; don't set 0 for diffuse — use high roughness. Cavity maps: BaseColor = CavityOldBaseColor, Specular = Cavity0.5. Measured specular from IOR (water 0.255, skin 0.35, ice 0.224).