microgeometry

Microgeometry denotes geometric features that exist at microscopic scales, typically at levels below what is perceived in everyday macroscopic geometry. It focuses on fine topography, roughness, grain structure, pores, and other small-scale forms that shape how a surface or material interacts with forces, fields, or signals. Because microgeometry often governs microscale phenomena, its effects may not be predictable from larger geometry alone and are studied with specialized measurement and modeling techniques, spanning scales from micrometers to nanometers.

In materials science and tribology, microgeometry influences contact mechanics, adhesion, friction, wear, lubrication, fatigue, and failure. The roughness and texture of a surface determine the real area of contact and the distribution of stresses. Characterization uses profilometry, scanning electron microscopy, atomic force microscopy, and optical methods. Common roughness metrics include Ra (average roughness), Rq (root-mean-square roughness), and Rz. Surface engineering can tailor microgeometry through finishing, coatings, or texturing to enhance performance.

In computer graphics, microgeometry is associated with microfacet models that represent a surface as an ensemble of tiny facets with various orientations. These microgeometric details govern how light is reflected or refracted, affecting specular highlights and shading. Parameters such as roughness control the distribution of microfacet normals; common models include Beckmann and GGX. Beyond graphics, microgeometry is relevant in porous media flow, lithography, and nanotechnology, where the micro-scale geometry informs transport, optical scattering, and reactive surface area.