In 3D rendering, it is useful to have texture maps which define a number of material characteristics. One such characteristic is metalness. Technically, all mat

In 3D rendering, it is useful to have texture maps which define a number of material characteristics. One such characteristic is metalness. Technically, all materials fall into one of two categories, metal and dielectric (the values in between are a convenience to prevent aliasing, since texels can't address individual atoms), each with different rules for shading. For example, dielectrics have specular reflection which is consistent across the visual spectrum; metals can have a coloured specular reflection. Recovering specular, metalness, normal, and roughness data in a controlled lighting environment also allows you to capture accurate albedo (aka diffuse color) textures. Metalness textures are an important part of current "Physically Based Shading" techniques, in both realtime and offline rendering, because they allow materials to react consistently to different lighting environments.