A special light source is a level object which doesn't define any geometric data. However, it allows the user to use any geometric object as a source of light; all sub objects radiate light. If the sub object is a single point, a point light is achieved. By using a NURBS curve as a sub object, one can create one dimensional area lights. Using a rectangle creates a two dimensional area light. The colors of sub objects of a special light sources are taken into account, including texture mapped colors in a 'Light properties' shader.
Special light specific options:
Quality - The illumination sampling quality. Defines how densely the sub geometry surfaces are evaluated for estimating the total illumination. A high quality value increases rendering time but produces smooth shadows, whereas low values render quickly but with dithered shadows. The bigger the sub object are, the higher quality value is needed for a proper quality.