Radiance(光亮度）: Note that it is the foreshortening of surfacearea in radiance, which is in contrast to theother area-based quantity irradiance （辉度）that are non-directional
Radiance (光亮度） • Note that it is the foreshortening of surface area in radiance, which is in contrast to the other area-based quantity irradiance（辉度） that are non-directional
SourceRadiance（光亮度）dAReceiverForeshorteningAn intuitive way to explain thisforeshortening factor in radiance is toconsider radiance as a flow of energy from asource to a receiver as exhibited in thefigure for a receiver perpendicular to theflow direction
Radiance (光亮度） • An intuitive way to explain this foreshortening factor in radiance is to consider radiance as a flow of energy from a source to a receiver as exhibited in the figure for a receiver perpendicular to the flow direction
（光亮度）Radiance: Defined respect to the apparent surface as:dpSourceL=dA cos do: Foreshortening ofAreadAReceiver- the area perpendicularForeshorteningtotheflowdirection
Radiance （光亮度） • Defined respect to the apparent surface as: • Foreshortening of Area – the area perpendicular to the flow direction dA d d L cos
(光亮度)Irradiance (辉度)from radiance: Irradiance is the integral of radianceover hemisphered@E=L()cos OddAQ-9is the hemisphere of incoming directions- L is the incoming radiance
Irradiance (辉度) from radiance （光亮度） • Irradiance is the integral of radiance over hemisphere – is the hemisphere of incoming directions – is the incoming radiance ( )cos d E L d dA L
BRDF Definition and PropertiesBRDF DefinitionBRDF Properties-reciprocity(可逆性)（能量守恒）-energy conservation（绘制方程）- rendering equation
BRDF Definition and Properties • BRDF Definition • BRDF Properties – reciprocity (可逆性) – energy conservation （能量守恒） – rendering equation （绘制方程）