Denoising just landed in Cycles Renderer and it’s far more capable than we ever imagined. Let’s dive in.

Here is a cornell box with 500 samples:

It’s almost not usable at any resolution due to how noisy it is. Let’s render again with denoise using the default settings.

At virtually the same render time, the image is far cleaner than any postprocessing denoiser is capable of. This is because as a builtin denoiser, it’s able to use data from various internal passes to reconstruct a cleaner image.

Just look at how it’s able to pull the detail from the pillow and reconstruct the shape of the teapot! Sure there are artifacts, but the denoiser is really designed to help you get rid of that last bit of noise. You know, the noise that forces you to render at 10000 samples rather than 3000. The noise that forces you to triples your render time.

So let’s try rendering this scene at a more reasonable sample count of 3000. It’s almost usable, but still noisy.

Smooth as butter, and without any visible artifacts.

However, it’s not perfect. We’ve encountered some artifacts even at high sample count when dealing with extremely bright reflection and refractions. Take this scene for example:

And here is the denoised version:

See those black halo artifacts around the balls? They are a result of the denoising filter breaking down at high brightness. A temporary solution is to use clamp direct to limit the brightness of the pixel. This is against our usual recommendation to not touch the clamp value, because it basically defeats the purpose of using a physically realistic pathtracer. But in this case, it’s the only quick way to fix the artifacts. In our case, setting the clamp direct to a high value of 100 is enough to remove the artifact.

Flawless.

So in summary, we are very excited to see how well the denoising feature is working. It can easily cut down render time by half when used correctly. Check back in a few days to see our results on denoising animations.