Dielectric vs Metallic: Avoiding the 'Steel Look' in 3D Product Renders
A deep dive into Fresnel equations, conductive vs non-conductive reflections, and why software defaults often ruin organic 3D models.
1. The Physics of Surface Reflection
Conductors (metals) have no diffuse reflection; all reflected light comes from the surface layer, and the reflection is tinted by the metal's albedo (e.g., gold reflects yellow).
Dielectrics (non-metals) transmit refracted light into their sub-surface, scattering it as diffuse albedo color, while reflecting a pure white specular highlight governed by the Fresnel effect.
When a non-metal material is given a metalness value like 0.20 or 0.35, the shader extinguishes its rich diffuse color and turns the surface into tinted chrome. The solution is simple: keep metalness at 0.00 for all organic matter.
Summary & Key Takeaway
Respecting the binary nature of metallic vs dielectric materials is the single most important rule in professional 3D product rendering.
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