Materials with emission properties can also use Multiple Importance Sampling. This results in the engine more accurately projecting light and further decreasing noise.įrom Blender 2.8 onward, this option can be found and turned on in your light’s Object Data Properties tab under Multiple Importance, though it’s activated by default when a light is inserted into a scene.

However, by also applying MIS, you activate indirect light sampling, which helps Cycles calculate light rays that bounce indirectly to a light source. Increasing the size of your light source definitely helps reduce fireflies and results in a cleaner image. If the rendering engine has to work harder to calculate and produce how elements are projected such as area lights and materials with glossy reflections such as glass, the results will include some level of noise. Right off the bat, it should be no surprise to any seasoned Blender user that small lamps are one of the largest culprits for noise-especially in Cycles. When inserting a light into a scene, it only uses direct light sampling at first, meaning that light rays that bounce directly to the lamp are being sampled. Though this algorithm certainly comes at a cost in your rendering times, and it doesn’t work the same way for every element represented in a scene, MIS can undoubtedly help beautify your final image and make those fireflies vanish. Multiple Importance Sampling is a process that essentially helps these light sources to better find their pathways, which can eliminate noise. However, not all light sources are handled the same way and sometimes Cycles can’t anticipate every light ray or its path, which leads to noise. The Cycles engine uses path tracing to simulate light from emitter sources and anticipate how that light bounces on objects and materials located in a scene. This solution is to activate an algorithm known as Multiple Importance Sampling (MIS). However, when these options have been exhausted, there is still one that is often overlooked due to its occasional instability, as well as its inconsistent activation when starting to create a new scene. Multiple Importance Samplingįireflies are a common issue, especially with Cycles and indeed, there are multiple solutions to help reduce the noise in your renders.

When using Cycles to render a scene, you may still find your renders suffering from a great amount of noise and dead, burnt-out pixels or “fireflies.” Keep reading to learn more about one trick that is often overlooked-Multiple Importance Sampling. One of the most important aspects of producing a beautiful final image is noise reduction.

Blender 2.9 denoise