Inverse decay of light and an alternative to traditional image based lighting and a move to incident light fields.
Let me take you back, way back to year 9 in high school in 1985, where I was introduced to light and photography and the inverse squared rule of light decay.
In black and white photography, you expose of piece of photosensitive paper to light for a period of time using an enlarger then go an develop that exposure with a chemical reaction in a tray and the darkness develops in front of your eyes.