3D Terminology

In this article, we cover some common terms that you’ll find used with 3D Rendering software.

CPU vs GPU Rendering

Think of the central processing unit, or CPU, as your computer’s brain and control center. A graphics processing unit, or GPU, is there to render 3D graphics and to help the CPU perform its calculations. The CPU is based on single cores so it works on one bit of data at a time. The GPU is designed for parallel processing so they can work with a lot of data simultaneously. To sum it up, a quote from Kevin Krewell from Nvidia explains it well: “Architecturally, the CPU is composed of just a few cores with lots of cache memory that can handle a few software threads at a time. In contrast, a GPU comprises hundreds of cores that can handle thousands of threads simultaneously.”

Some 3D renderers will utilize the GPU instead of the CPU, which can mean faster renders, but the downside is that GPUs are limited to the amount of VRAM or video memory. Many renderers are hybrid and use both the CPU and GPU.

GPU vs. CPU Video Rendering and Video Editing

Roberto Blake gives an excellent overview of whether you should choose GPU or CPU rendering.

BDSF – Bidirectional Scattering Distribution Functioning

A mathematical function that lends itself to credible shading. It captures how light reflects from and transmits through the material. In the video below from Udacity, he also talks about BSSRDF, which stands for Bidirectional Surface Scattering Reflectance Distribution Functioning. Watch the video below for an explanation.

Biased vs. Unbiased

Biased means that the renderer will estimate values, or do a bit of educated guessing using mathematical functions, and not calculate every single pixel. The benefit is that it’s much faster. The downside is that the results may not be absolutely accurate.

Unbiased, however, means that every pixel is calculated with no interpolation between pixels. Biased rendering methods include light tracking, bidirectional path tracing, and metropolis light transport.

Many renderers are capable of producing both unbiased and biased renderers.

Grant Warwick about Bias and Differences of 3D Rendering Engines

Further reading:

Global Illumination

Global Illumination is the algorithm that the software uses to recreate natural lighting from the real world. There are several types of algorithms such as radiosity, ray tracing, beam tracing, cone tracing, path tracing, Metropolis light transport, ambient occlusion, photon mapping, and image-based lighting. Even more, these can be used on their own or in combination with each other to create better results. [Source: Wikipedia: Global Illumination]

C4D Fundamentals | 07 – Advanced Rendering – Understanding Global Illumination

While this video is targeted to Cinema 4D, much of the information applies to any other 3D software.

Monte Carlo Method

This is a common algorithm for photo realism used by 3D software and it seems to be tied in with probability in gambling! To explain, “Monte Carlo methods are also efficient in solving coupled integral differential equations of radiation fields and energy transport, and thus these methods have been used in global illumination computations that produce photo-realistic images of virtual 3D models, with applications in video games, architecture, design, computer-generated films, and cinematic special effects.” [Source: Wikipedia: Monte Carlo method]

Further reading:

Embree Ray Tracing Kernels

Embree, developed at Intel, is a collection of high-performance ray tracing kernels. Hence, it is explained in the video below from Intel.

Many renderers use Embree ray tracing kernels. In addition, V-Ray Next includes a custom Embree ray tracing library “which speeds up anything from proxies to motion blur.” [Source: Interview: V-Ray Next and the Future of Rendering – CG Channel] FluidRay RT, Corona Render, and others also use it.

Further reading:

Physically-Based Rendering (PBR)

Finally, Physically based rendering, often abbreviated as PBR, uses mathematical theories that allow for photorealistic renderings.

What is PBR? Physically-Based Rendering Explained

Further Reading:


A VDB volume is a data structure that works with sparse volumetric data and is incredibly efficient. VDB stands for either Volumetric Data Blocks. or Voxel Data Base [source]. The VDB format was developed by DreamWorks Animation in 2012 for storing 3-dimensional grids of data.

The OpenVDB library is a library of open-source C++ tools that works in Cinema 4D, Renderman, and Houdini.