What is render noise/grain/fireflies?
Render noise, grain, and fireflies are small and distinct bright lighting flaws in your render.
Render noise has the potential to degrade an otherwise excellent render or animation. The good news is that you can eliminate fireflies in Blender using a few tricks. Follow the following steps to eliminate noise from your renders in cycles render.
1. Eliminate render fireflies using the AI-powered denoise composition node in Blender
The Denoise node is used to denoise renderings from Cycles and other ray-tracing renderers. This helps to greatly cut render time by rendering with fewer samples. It employs Open Image Denoise, which uses machine learning to convert noisy pictures into clean ones.
- Download and install Nvidia OptiX™
- Launch Blender and ensure you are in Cycles render. Change Blender render device from CPU to GPU
- Activate denoising data. Use the image below to refer
- Render your scene and go to the compositor
- From the compositor, click ‘Shift + A’. On the search box type ‘denoise’. Select the ‘Denoise’ node
- Connect the Denoise node to other nodes as shown in the image below
- Ensure HDR is checked on the denoise node
- Do another render and see the difference
2. Eliminate render noise by optimizing your sampling and denoising settings
The following are the Blender sampling settings that I use on my projects by default. They not only produce clean renders, but they also cut my render times in half.
3. Avoid rendering noise/fireflies by using Blender’s Eevee render engine
Eevee is Blender’s real-time render engine built with OpenGL that focuses on speed and interactivity while rendering PBR materials. Eevee can be used interactively in the 3D Viewport as well as producing high-quality final renders.
Because Eevee materials are built using the same shader nodes as Cycles, it is simple to render existing scenes. This makes Eevee ideal for previewing materials in real time for Cycles users.
Eevee, unlike Cycles, is not a ray trace render engine. Instead of processing each ray of light, Eevee uses a technique known as rasterization. Several techniques are used in rasterization to approximate how light interacts with objects and materials. While Eevee is intended to follow PBR concepts, it is not without flaws, and Cycles will always give more physically realistic renders. Eevee has a lot of limitations because it employs rasterization.
4. Save the above settings so they become your default render settings every time you launch Blender
On the top left corner of Blender, click ‘File’. On the dropdown, go to Defaults > Save Startup File
