<p>The light is directional, it is represented in polar or Cartesian diagramsdescribed as light distribution curves. The most homogeneous light distribution curve is obtained from a flat and diffuse radiating surface. In optics, Lambert's cosine law says that the radiant intensity observed from a "Lambertian" surface is directly proportional to the cosine of the angle &theta; between the observer's line of sight and the surface normal. The law is also known as the cosine emission law or Lambert's emission law</p> <div></div>