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[non-Blender] The theory of Physically-Based Rendering and Shading


Allegorithmic presents a in-depth article on the interaction of light and matter and the basics of Physically-based rendering in this article.

Light is a complex phenomenon as it can exhibit properties of both a wave and a particle. As a result, different models have been created to describe the behavior of light. As texture artists, we are interested in the Light Ray Model as it describes the interaction of light and matter. It’s important for us to understand how light rays interact with surface matter because our job is to create textures that describe a surface. The textures and materials we author interact with light in our virtual worlds and the more we understand about how light behaves, the better our textures will look.

In this guide, we will discuss the theory behind the physics through which physically-based rendering models are based upon. We will start with a light ray and work up to defining the key factors for PBR.

About Author

Bart Veldhuizen

I have a LONG history with Blender - I wrote some of the earliest Blender tutorials, worked for Not a Number and helped run the crowdfunding campaign that open sourced Blender (the first one on the internet!). I founded BlenderNation in 2006 and have been editing it every single day since then ;-) I also run the Blender Artists forum and I'm Head of Community at Sketchfab.


  1. Very nice,almost when i was done with my survey about shaders.Keep the articles coming :)

    p.s. anyone knows sites with the traits of real life materials so we can learn how much light they absorb or send away etc.?

  2. I'm glad to see Allegorithmic finally offering some material on the matter. For a lot of guys like myself (particularly Unreal Engine 4 licensees), it's been pretty tricky to find some reliable material on physically-based rendering, both for theory and workflow. We've been scavengers, for the most part.

    Here are a couple more mainstay resources on PBR I've found along the way:

    I'm looking forward to what Vol. 2. may cover. I hope it's a guide on PBR workflow, particularly using Allegorithmic's software.

    I've learned a lot on my own so far, but I'm always interested in seeing more discussed about the subject. I'm also very interested in their programs, but alas, there's virtually no ample documentation on it. And what little is out there, it's pretty ambiguous for most folks.

    Heck, I'd like to see some game companies showing their real-world usage of PBR tools, such as Substance Designer and Substance Painter. There's not even much a notable example by way of games so far that I can use see some real-world results. PBR is the biggest step in the industry, and yet, there's so relatively little available about it.

    Maybe Allegorithmic can keep some of this in mind while developing subsequent volumes to this series. ;)

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