When considering light – which is “visible” electromagnetic radiation – we are concerned on the one hand with energy and on the other with a sensation obtained through the eye – two principally dissimilar things.
The human eye is an extremely sensitive and complex sense organ. A large proportion of the brains function is concerned with vision and perception. In lighting simulation we are not trying to model the way the eye and brain work but rather the way a more simple device operates – the camera, hence the term photo-realistic images.
Lighting is an art and a science. The lighting quality of a space may be judged on a number of quantitative and qualitative criteria. It is important that these criteria are not seen in isolation to one another, for each is dependent on and influenced by each of the others.
The principal quantitative criteria are:
the lighting level
luminance (or brightness) distribution in the field of view
the freedom from disturbing glare
The principal qualitative criteria are:
the light colour, colour appearance and colour rendering
