Base Color controls non-reflective surface detail for non-metallic surfaces. Defaults to Gray50(R=0.5,G=0.5,B=0.5) if not specified.

Metalness controls how the surface reflects light, either as raw metal or as a non-metallic (dielectric) surface. At full metalness, the surface is fully reflective and the base color controls the reflection strength and color. At zero metalness, the surface is fully reflective only at grazing angles, and the base color has no effect on specular reflection. Metalness is in the range [0, 1]. Defaults to 1.0 if not specified.

Roughness defines micro-surface bumpiness, which essentially controls how blurry or sharp reflections will be. Roughness is in the range [0, 1]. Defaults to 1.0 if not specified.

Transmission is used to describe the percentage of light that is transmitted through the surface of the material and handles infinitely thin volumes (e.g. stain or transparent foil). This effect, as opposed to alpha coverage, more accurately represents refractive materials like glass and water, which also show visible reflections. Transmission is in the range [0, 1]. Defaults to 0.0 if not specified.