Often, the quality of a simulation is judged by its proximity to reality and the question is asked as to whether the rendering is correct or no more than a photorealistic representation. The criterion of physically correct data refers to the numerical values provided by the quantitative simulation. Screen displays or colour printouts can never give the same impression as the actual environment. A photographer controls the incident light by opening or closing the aperture and the same creative approach is taken in the production of a rendering. A further limitation is the range of contrasts on the output media. None of the following can correctly reproduce the luminance contrast which will be seen in reality: colour printout, screen display or the projected image of a beamer.
A photorealistic impression of a qualitative simulation can provide a far more authentic representation of the anticipated lighting effect, such as the progression of light and shadow or reflections off surfaces.