What is Lamberts laws or Lamberts first law, second law and third law:
Lambert's laws (J.H. Lambert)
Lambert's first law: The luminance on a surface lighted up by light falling on it perpendicularly from a point source is proportional to the inverse square of the distance among the source and surface.
Lambert's second law: When the rays meet the surface at an angle, then the luminance is proportional to the cosine of the angle with normal.
Lambert's third law: The luminous intensity of light reduces exponentially with the distance as it travels via an absorbing medium.