IEC 60050 - International Electrotechnical Vocabulary


IEVref:	845-25-089		ID:
Language:	en		Status: Standard

Term:	bi-directional reflectance distribution function
Synonym1:	BRDF
Synonym2:
Synonym3:
Symbol:	ρ(θ_i,ϕ_i,θ_r,ϕ_r,x_r,y_r,λ)
Definition:	function describing the change with direction of irradiation (θ_i,ϕ_i) and direction of view (θ_r,ϕ_r) of the radiance of a surface element (x_r,y_r) in a given direction of view at a given wavelength λ, $L_{r} (θ_{r}, ϕ_{r}, x_{r}, y_{r}, λ)$ , with respect to the irradiance incident on the medium from the given direction of irradiation at the given wavelength, $E_{i} (θ_{i}, ϕ_{i}, λ)$ $ρ (θ_{i}, ϕ_{i}, θ_{r}, ϕ_{r}, x_{r}, y_{r}, λ) = \frac{d L_{r} (θ_{r}, ϕ_{r}, x_{r}, y_{r}, λ)}{d E_{i} (θ_{i}, ϕ_{i}, λ)}$ Note 1 to entry: The bi-directional reflectance distribution function is expressed in steradian to the power minus one (sr⁻¹). Note 2 to entry: See also "radiance coefficient". Note 3 to entry: This note applies to the French language only.
Publication date:	2020-12
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θiϕiθrϕrxryrλ L r ( θ r , ϕ r , x r , y r ,λ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadYeadaWgaaWcbaGaaeOCaaqabaGccaGGOaGaeqiUde3aaSbaaSqa aiaabkhaaeqaaOGaaiilaiabew9aMnaaBaaaleaacaqGYbaabeaaki aacYcacaWG4bWaaSbaaSqaaiaabkhaaeqaaOGaaiilaiaadMhadaWg aaWcbaGaaeOCaaqabaGccaGGSaGaeq4UdWMaaiykaaaa@4907@ E i ( θ i , ϕ i ,λ) MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX garuavP1wzZbItLDhis9wBH5garmWu51MyVXgaruWqVvNCPvMCG4uz 3bqee0evGueE0jxyaibaieYdi9WrpeeC0lXdh9vqqj=hEeea0xXdbb a9frFj0=OqFfea0dXdd9vqaq=JfrVkFHe9pgea0dXdar=Jb9hs0dXd bPYxe9vr0=vr0=vqpWqaaeaaciWacmGadaGadeaaeaGaauaaaOqaai aadweadaWgaaWcbaGaaeyAaaqabaGccaGGOaGaeqiUde3aaSbaaSqa aiaabMgaaeqaaOGaaiilaiabew9aMnaaBaaaleaacaqGPbaabeaaki aacYcacqaH7oaBcaGGPaaaaa@4334@

ρ (θ_{i}, ϕ_{i}, θ_{r}, ϕ_{r}, x_{r}, y_{r}, λ) = \frac{d L_{r} (θ_{r}, ϕ_{r}, x_{r}, y_{r}, λ)}{d E_{i} (θ_{i}, ϕ_{i}, λ)}

Note 1 to entry: The bi-directional reflectance distribution function is expressed in steradian to the power minus one (sr⁻¹).Note 2 to entry: See also "radiance coefficient".Note 3 to entry: This note applies to the French language only.