Lighting a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square metre (cd/m). The CGS unit of luminance is the stilb, which is equal to one candela per square centimetre or 10 kcd/m. The amount of useful light emitted from a source or the luminous flux is measured in lumen (lm). The SI unit of illuminance and luminous emittance, being the luminous power per area, is measured in Lux. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes
Borel measure Borel measure In mathematics, specifically in measure theory, a Borel measure on a topological space is a measure that is defined on all open sets (and thus on all Borel sets). Some authors require additional restrictions on the measure, as described below. Let formula_1 be a locally compact Hausdorff space, and let formula_2 be the smallest σ-algebra that contains the open sets of formula_1; this is known as the σ-algebra of Borel sets. A Borel measure is any measure formula_4 defined on the σ-algebra of Borel sets. Some authors require in addition that formula_4 is locally compact, meaning that formula_6