Stilb (unit) Stilb (unit) The stilb (sb) is the CGS unit of luminance for objects that are not self-luminous. It is equal to one candela per square centimeter or 10 nits (candelas per square meter). The name was coined by the French physicist André Blondel around 1920. It comes from the Greek word "stilbein" meaning "to glitter". It was in common use in Europe up to World War I. In North America self-explanatory terms such as candle per square inch and candle per square meter were more common. The unit has since largely been replaced by the SI unit: candela per square
Spherical measure "r" > 0, where "A" denotes the “inflation” of "A" by "r", i.e. In particular, if "σ"("A") ≥ ½ and "n" ≥ 2, then Spherical measure In mathematics — specifically, in geometric measure theory — spherical measure "σ" is the “natural” Borel measure on the "n"-sphere S. Spherical measure is often normalized so that it is a probability measure on the sphere, i.e. so that "σ"(S) = 1. There are several ways to define spherical measure. One way is to use the usual “round” or “arclength” metric "ρ" on S; that is, for points "x" and "y" in S, "ρ"("x",