text: Calculation of radiative heat transfer between groups of objects, including a cavity or surroundings requires solution of a set of simultaneous equations using the radiosity method. In these calculations, the geometrical configuration of the problem is distilled to a set of numbers called view factors, which give the proportion of radiation leaving any given surface that hits another specific surface. These calculations are important in the fields of solar thermal energy, boiler and furnace design and raytraced computer graphics.
  The net radiative heat transfer from one surface to another is the radiation leaving the first surface for the other minus that arriving from the second surface.
  Formulas for radiative heat transfer can be derived for more particular or more elaborate physical arrangements, such as between parallel plates, concentric spheres and the internal surfaces of a cylinder.