| opt. |
B n (photometric brightness; the luminous intensity of any surface in a given direction per unit of projected area of the surface as viewed from that direction; units: expressed in candles per unit of area; stilb, sb: equal to 1 c/cm²; apostilb, asb: equal to 1/π c/m²; lambert, L: equal to 1/π c/cm²; foot-lambert, ff-L: equal to 1/π c/ft²); Flächenhelligkeit f (photometric brightness; the luminous intensity of any surface in a given direction per unit of projected area of the surface as viewed from that direction; units: expressed in candles per unit of area; stilb, sb: equal to 1 c/cm2, apostilb, asb: equal to 1/π • c/m²; lambert, L: equal to 1/π • c/cm²; foot-lambert, ft-L: equal to 1/π - c/ft²) |
