I learned physically based rendering (PBR) and non-physically based rendering (NPBR) when learning opengl and c++ for cg films and games.
They are two directions for using computer graphics that are constantly being developed. PBR is mainly used for CG films and AAA games, generally needing to take more time and resources as well as massive rendering times to create.
NPBR is generally used for avant-garde animations and most other games. Games have the requirement of having to run at a consistent frame rate - severely restringing the kinds of computation that can happen to display each and every frame. This means that other algorithms that approximate real life or stylize must be used to have a smooth experience - an ingenious and creative field.
Oil painting has an emergent kind of rendering. Where the mixture of paint and it's application determines the effect and can be compounded and controlled on-top of one another. It can be PBR, NPBR or both at the same time.
Oil painting has a great and deep breadth of effects it can portray - something many painters view as it's crowning feature.
This emergent rendering is part based on intuition of the complex mixtures of oil and the technical and conscious understanding of it. It's a mixture of chance and control, of what one can express in words and one has no words to express.
It allows for a fuller understanding of the medium.
It allows for expression.
It allows for experimentation.
It allows for failure - something the restrictive syntax of code does not.
In the same ways we apply rules of rendering to the canvas, could we not apply rules of rendering to digital work?
Could we not amplify this natural emergent rendering with our own rules? Instead of the ones dictated by the chemicals oil paint.
What more could be expressed.