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The V-Ray Denoiser takes an existing render and applies a denoising operation to it after the image is completely rendered out via normal means. The denoising operation detects areas where noise is present and smooths them out. Images can also be denoised using the Standalone Denoise Tool included with the installation of V-Ray for Maya.

Because the V-Ray Denoiser operates on other render elements (like RGB_Color ) rather than being part of the rendering process itself, the denoising operation does not require re-rendering of the scene.

There are two denoising engines to choose from - the Default V-Ray denoiser and the NVIDIA AI denoiser (V-Ray's implementation of NVIDIA's AI-based denoising algorithm). See the Denoising Engines section for more information.

The V-Ray Denoiser has three preset options for its settings: Default, Mild, and Strong. Parameters can also be adjusted directly by using the Custom preset.

 

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Using the Denoiser

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When rendering, the V-Ray Denoiser automatically adds a few render elements in the V-Ray frame buffer which are required by the denoising algorithm. Some of them are standard render elements like Diffuse and Reflection Filter. A few special render elements are also generated:

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  • The noiseLevel render element is the amount of noise for each pixel in greyscale values, as estimated by the V-Ray image sampler.
  • The defocusAmount render element is non-black only when depth of field and motion blur are enabled, and contains the estimated pixel blurring in screen space.
  • The VRayDenoiser render element, when generated, contains the final image that results from noise removal. Whether this render element is generated depends on the Mode selection.
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The denoiser can only work with the new variance-based adaptive sampling method introduced in V-Ray 3.30

 

 

UI Path

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||Render Settings window|| > Render Elements tab > Denoiser

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While the denoiser can be quite effective at removing noise, it is not perfect. Very noisy images can lead to artifacts and loss of image detail. For most scenes, use the Progressive image sampler with the the Noise threshold parameter set to 0.05 or lower. Additionally, the denoiser works best when the noise levels across the image are similar (when the noiseLevel channel is as close to uniform gray as possible), so using very low sampling is not recommended.

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When rendering animations, disabling the Animated noise pattern option in

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the DMC sampler

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 rollout generally improves the results.

Using

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the Standalone Denoise Tool

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 on the rendered frames can additionally improve the quality of the animation.

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You can modify the frequency at which the denoiser is updated during progressive rendering via the Post effect rate parameter located in V-Ray's Settings > System > Post effects rollout. Increase the value if you want to see the denoised image more often during IPR with V-Ray and V-Ray GPU. However, note that using large values is only useful in IPR and is not recommended for the final rendering.

 


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Example:

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Default V-Ray denoiser

 

The example below illustrates how vrayRE_Denoiser works using the presets. A purposely noisy render was set up using the Progressive image sampler with Render Time set to only 10 minutes to leave plenty of noise in the render. To better see the noise level in each image, click the image to see it at full sizethe Default V-Ray denoiser works after more samples are made with the Progressive image sampler. When the samples are too few, there's not enough information for the denoising to produce a smooth result.

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RGB Color Render Element prior to denoising

 

 

 

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vrayRE_Denoiser Render Element (Mild Preset)

 

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vrayRE_Denoiser Render Element (Default Preset) 

 

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vrayRE_Denoiser Render Element (Strong Preset)

 
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Sampling pass 1

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  Sampling pass 2

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  Sampling pass 4

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Sampling pass 8

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  Sampling pass 16

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  Sampling pass 64

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vrayRE_Denoiser Render Element
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The vrayRE_Denoiser Render Element
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The original vs. the denoised image after 64 passes.

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Example:

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The noiseLevel Render Element shows where areas of noise have been detected in the scene. White areas have the most noise, black areas have no noise, and gray areas have varying levels of noise.

 

NVIDIA AI denoiser

 

The example below illustrates how the NVIDIA AI denoiser works after more samples are made with the Progressive image sampler. When the samples are too few, there's not enough information for the denoising to produce a smooth result.

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RGB Color Render Element prior to denoising

 

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Sampling pass 32

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Sampling pass 64

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noiseLevel Render Element
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The original vs. the denoised image after 64 passes.

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Denoising Separate Render Elements

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Not all Render Elements support the Denoise function. For
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Some render elements don't have a Denoise option, as they don't produce color information. For this reason, it makes no sense to denoise them, as this would distort the data. For example, ZDepth and Velocity data doesn't need denoising, just like masks like the Cryptomatte or the MultiMatte don't either. For more information, please see their the respective render element page.

 

Denoising Animations

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When denoising animations, it is recommended to use the Standalone Denoiser Tool. Unlike the denoiser integrated in the UI, the standalone tool can do frame blending for animations, which reduces flickering. The integrated denoiser only works on the rendered frame and does not take the next and previous frame(s) into account, like the standalone tool does.

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The NVIDIA AI denoiser does not perform frame blending and will likely produce flickering when denoising animations.


Denoising in IPR

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When denoising IPR renders, it is recommended to use the NVIDIA AI denoiser and set the Post effects rate parameter to 100. The NVIDIA AI denoiser produces a noise-free result instantaneously and Post effects rate of 100 ensures that you see the noise-free result as often as possible..

To use the denoiser in IPR with the VFB:

  1. Add a Denoiser render element and change the Engine to NVIDIA AI denoiser.
  2. Set the the Post effects rate parameter to 100.
  3. You can now start IPR in the VFB.

To use the denoiser with Viewport IPR:

  1. Start V-Ray IPR in the Maya viewport using the V-Ray logo icon in the viwport
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  2. Enable the viewport denoiser by clicking the Denoiser icon ( Image Added ) next to the V-Ray logo. For viewport IPR denoising, the denoiser engine is automatically set to the NVIDIA AI denoiser and the Post effects rate is adjusted to 100.


Notes

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  • Image denoising takes place after the frame has been rendered, so the results of denoising will not show up until all rendering has finished.

  • Textures or materials such as VRayStochasticFlakesMtl that could be considered to have a purposely noisy look are not considered "noisy" by vrayRE_Denoiser, and are not affected by the noise removal process.

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