Goniophotometry or goniometric optical scatter measurement is the technique of measuring the angular distribution of light, possibly wavelength-dependent, scattered from a surface. Goniophotometry involves the use of a goniophotometer to measure intensity distributions from lamps and luminaries and to evaluate the gloss of paints and other surface finishes.
References ASTM E2387-19 "Standard Practice for Goniometric Optical Scatter Measurements" [1]