Which material property primarily controls the sharpness and clarity of reflections?

• A. Emissive
• B. Specular Value
• C. Albedo
• D. Roughness

Answer: (B)

How sharp reflections appear is determined by the surface’s microstructure. In most physically based shading systems, roughness controls how dispersed reflected light is across the surface. Low roughness means a very smooth surface, producing crisp, mirror-like reflections; high roughness scatters light and makes reflections blurry and diffuse. The specular value affects how bright the reflections are, i.e., the intensity of the mirror-like component, but not the clarity or sharpness of those reflections. Emissive and Albedo influence color and emission, not the clarity of reflections. So the property that primarily governs the sharpness and clarity of reflections is roughness.