Hacker News Reader

Comment by hahamrfunnyguy | Hacker News Reader

What is PBR? Not Pabst Blue Ribbon! Here's a brief description from Adobe:

Physically based rendering (PBR), sometimes known as physically based shading (PBS), is a method of shading and rendering that provides a more accurate representation of how light interacts with material properties. Depending on which aspect of the 3D modeling workflow is being discussed, PBS is usually specific to shading concepts while PBR refers to rendering and lighting. Both terms describe the process of representing assets from a physically accurate standpoint.

View on HN

PBR textures don't include just the usual colored images, but also other surface properties that influence how specific surfaces interact with light. Like roughness, glossiness, elevation (surface normal vectors), whether the surface is a metal, whether it has specular highlights, whether it appears fuzzy, whether it is partly translucent (like skin) and so on. The combination of such textures is called a (PBR) "material".

It's called "physically based" because there exist simple physics formulas for these properties, so it luckily isn't necessary to simulate the all microphysical details that cause them in real objects. Similar to how one can describe a gas with a few parameters from thermodynamics without considering the molecular details that explain those phenomena.

In old 3D renders everything looked like plastic because they had only very primitive surface properties.

That is true but not whole story. I believe when people talk about PBR Textures they most often use PBR synonymously to "Principled Shader", "BSDF Shader" or "Disney Shader" (all meaning roughly the same thing).

Here is my whole comment. Somehow the last part I posted in an edit magically disappeared:

When it comes to 3D data, exchanging geometry has been possible for a long time. Essentially and most of the time we just use triangles as the lowest common denominator. Most of the difficulties are more or less accidental complexity because of different formats.

When it comes to textures this was not possible for a long time, because every renderer used its own algorithm and they all had different parameters. There was no lowest common denominator.

When Disney invented BSDF it allowed the exchange of realistic materials for the first time. The "format" won and is what is sold or given away as "PBR-Textures".j

[deleted]

Reply on news.ycombinator.com