There are so many renderers available out there. How do you know which is the best for you?
Each renderer works differently and gives different results. Below is a breakdown of what the different renderers offer, not a review, so you can decide which renderer is right for you.
But firstly, we will see the main technical concepts to consider for evaluating a render engine: CPU vs. GPU, Biased/Unbiased, Physically-based rendering.
CPU vs. GPU Rendering
Think of the central processing unit, or CPU, as the brain and control center of your computer. 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 at once. 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 is composed of 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 a great overview of whether you should choose GPU or CPU rendering.
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, on the other hand, means that every pixel is calculated with no interpolation between pixels. Biased rendering methods include light tracking, path tracing, 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
- The Truth About Unbiased Rendering
- Should your renderer be biased or unbiased?
- Octane vs Corona vs Redshift has a nice explanation of biased vs unbiased.
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.
Finally, Physically based rendering, often abbreviated PBR, uses mathematical theories that allow for photorealistic renderings.
What is PBR? Physically-Based Rendering Explained
- Physically Based Rendering From Theory to Implementation, Second Edition, by Matt Pharr and Greg Humphreys
- Basic Theory Of Physically-based Rendering
- PBR Guide from Allegorithmic
- Maya Monday: How Physically Based Rendering Shaders Work
- Webinar Replay: NVIDIA: Transform Your Workflow with Physically Based Materials
Render Engines – Comparison Chart
(Render engines are ordered alphabetically. Data extracted from their respective websites. May 15, 2019)
Main source: Toolfarm