roughnessmetalnesscontrol

Roughness and metalness control are two fundamental properties in physically based rendering (PBR) used to describe how a material interacts with light. Roughness describes the microfacet surface roughness, determining how sharp or soft reflective highlights appear. Metalness (often called metallic or metalness) indicates whether a surface behaves like a metal or a non-metal (dielectric), which changes how light is reflected and tinted.

In typical PBR workflows, roughness and metalness are provided as grayscale textures or as scalar values. A roughness map uses values from 0 (very smooth, sharp highlights) to 1 (very rough, diffuse reflections). A metalness map uses values from 0 (dielectric) to 1 (metal), where metals reflect their environment with strong, colored reflections and dielectrics reflect more neutrally and with less intense coloration. Combined with an albedo or base color map, these properties determine the overall appearance: dielectric surfaces use the base color for diffuse reflection and have lower reflectivity at grazing angles, while metals use the base color as the reflectance color and exhibit high, colored reflections.

Practical usage involves textures or sliders in a material editor. Roughness and metalness maps should be in linear space (for roughness) or as grayscale inputs, with careful handling of gamma settings in the rendering engine. Common pitfalls include swapping metallic and roughness channels, using incorrect space for textures, or neglecting ambient occlusion in the final shading. When used properly, roughness and metalness controls enable realistic material variation with consistent lighting responses across lighting conditions.