Light in the original Microsoft Train Simulator. The lumination was set using on a standard.

Now the calculated luminosity. Slight contours are visible but obscured by grey fog calculated from overall lumination and diffuse light levels.

To achieve a realistic atmosphere in this picture, we could have increased intensity and contrast but this is difficult here. With the aid of mathematical algorithms we reached a mean value such that brighter objects become a multiple that is doubled at each step. For darker segments we used the same system.

 

Another important component is the light ray analysis. We needed to find an algorithm which tracks the light ray and recognises when the light ray hits an object. Another analysis checks the objects material in order to determine the intensity of reflected light.