BA2 - Physically Based Rendering

What is Physically Based Rendering?

To describe what Physically Based Rendering (PBR) is I could go on for ages, instead I decided to make a short summary and bring up the most important parts.

What PBR does it that it uses measured surface values to create realistic shading/lighting to give a more realistic look of the specific material. This is technology that has excited in the film industry for some time and now implemented in game engines.

To put it very briefly, PBR makes it possible for artists to use real world measured surface values to define the different materials, and so achieve more realistic results.

The largest difference between traditional texturing and PBR is a more detailed and accurate behaviour of light and surfaces. What this does is that it allows an object to under different lighting conditions still look like the material the artist intended it to be. For example, it allow the players to still see that an object is meant to be metal even tho there is no light source close to the object to show this.

For PBR to achieve it’s realistic look it uses a lot of different information, such as: Diffusion, Reflection, Albedo, Energy Conservation etc. Here is a brief description of some of them.

Diffusion

The diffusion is what defines the colours of a surface. This happens when light hits a surface and within that surface, scatters the light around which results in the light reflecting in different angles. The light that get’s diffused generates heat and that is why wearing black clothes during a hot summer day generates more heat than white clothing. The light that reflects back after the diffusion is called Albedo (Whiteness).

(Image from: http://www.marmoset.co/toolbag/learn/pbr-theory)

Reflection:

Reflection happens when none of the light that hits the surface get’s diffused and instead reflects into a single outgoing direction. The colour of the reflection is generally based on the colour of the light. When it comes to various materials such as metal the reflection colour can get tint, gold is a good example of this since the reflection has a orange tint when light bounces of the material.

(Image from: http://www.marmoset.co/toolbag/learn/pbr-theory)