Design Nomenclature / Surface & Material
Anisotropy
Also called anisotropic reflection, anisotropic highlight, directional roughness
This entry has not been translated yet and is shown in English.
Roughness that differs along two tangent directions, stretching the highlight perpendicular to the surface's structure. Produced by anything unidirectional: brushed metal, hair, vinyl, satin weave. It needs a tangent frame to orient against, so it inherits every flaw in the UV layout and shears wherever the layout does.
Not to be confused with
- SheenAn extra grazing-angle lobe layered over the base response to approximate the soft bloom of fabric, where light catches the protruding ends of fibers standing off the surface. In the Disney formulation it is a tuned artistic control with no measured referent; later fiber-scattering models give it a physical basis it did not originally have.
- RoughnessThe statistical spread of microfacet normals across a surface, controlling how tightly reflected light clusters around the mirror direction. Low values concentrate energy into a small bright highlight; high values spread the same energy into a broad dim one. It is a distribution width, not a quantity of reflection.