Simulation programs include general light sources such as spot, point, area and sunlight. The representation of special luminaires, however, requires an interface that can import the light distribution data from the luminaires. These data records are available from most luminaire manufacturers and describe the specific light intensity distribution of each luminaire. The IES format is a common international data format. Luminaires with an asymmetric light distribution, for example, cannot be calculated correctly in any other way. The use of accessories such as a sculpture lens affects the light distribution and requires a separate data record.