The science of measuring light, photometry, specifically applies to light in a space. Photometrics gauges how humans perceive light — its coverage area, where light cuts off and the intensity of light in relation to distance from the light source. In practical terms, photometrics shows whether a lighting plan meets the qualitative and quantitative lighting requirements for a project.
Essentially, volumetric lighting refers to the illusion created when a lighting technique suggests a certain perspective, orientation or effect that increases, enhances or magnifies the sense of volume in a given space, context or application. In residential and commercial lighting design, volumetric lighting is often synonymous with task lighting. Light fixtures designed with optics that have a fully luminous and distinguishable beam spread and can be directed, with purpose, to light art, a table, produce in a market, etc.