Roughnesstextures

Roughnesstextures refer to grayscale textures used in physically based rendering to control the microfacet roughness of a surface. In a metalness/roughness workflow, the roughness texture provides per-pixel values that determine how sharply a surface reflects light. The value 0 corresponds to a perfectly smooth surface, producing sharp reflections, while 1 yields a completely rough surface with diffuse, spread out reflections. The term roughness texture is sometimes used interchangeably with glossiness maps in older pipelines; roughness and glossiness are inverses of each other, and some engines require converting between the two representations.

In modern shading models, roughness controls the distribution of microfacets (often via the GGX NDF), which determines the sharpness of specular highlights and the falloff of reflections. Lower roughness produces tighter, brighter highlights and clearer reflections; higher roughness yields broader, duller reflections. Roughness affects only the reflective component and is typically used in combination with metallic maps in the metalness/roughness workflow; it is generally independent of albedo/base color.

Creation and formats: Roughness textures can be authored procedurally or painted by hand, or derived from physical measurements. They are usually stored as single-channel grayscale images and sampled in the shader as linear data. Common file formats include PNG, TIFF, and EXR; many pipelines prefer non-animated, non-compressed formats for consistency. In most engines, roughness maps are combined with normal maps and metallic maps in a single material.

Practical considerations include maintaining consistent tiling, avoiding seams, and providing texture resolution appropriate for the object's size. Many engines treat roughness as a linear value; some authors store it in the alpha channel of other maps or in a separate texture, depending on the workflow.