NVIDIA Real-Time Denoisers

The NVIDIA Real-Time Denoisers (NRD) are a spatio-temporal API agnostic denoising library that’s designed to work with low ray per pixel signals. It uses input signals and environmental conditions to deliver results comparable to ground truth images.

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NRD in Ubisoft's Watch Dogs: Legion

Fast Ray Tracing Denoising Solution

Fast integration, fast real-time performance. NVIDIA Real-Time Denoisers will increase the efficiency of your art pipeline.

Designed to Work with 0.5 or 1 Ray Per Pixel

This highly performant ray tracing solution is built to provide real-time results for developers using a limited budget of rays per pixel. You can achieve exceptional denoising results using only .5 to 1 ray per pixel.

Works with DX11, DX12, and Vulkan

No matter which APIs you are using, NVIDIA Real-Time Denoisers are built to fit seamlessly into your workflow. Get started knowing that DX11, DX12 and Vulkan are all fully supported from day 1.

Full Source Code

Developers get the flexibility that comes with full access to source code. Build out and optimize NVIDIA Real-Time Denoiser to fit your unique use case.

Denoisers in NRD

ReBLUR is a denoiser based on the idea of self-stabilizing recurrent blurring. It is designed to work with diffuse and specular signals generated with low ray budgets. In fact, ReBLUR supports checkerboard rendering, producing reasonable results when casting just half a ray per pixel. Compared to SVGF (Spatiotemporal Variance-Guided Filtering), which was introduced in 2017, ReBLUR offers more realistic lighting with better temporal stability, all while being 50% faster. To see ReBLUR in action, play CD Projekt Red's Cyberpunk 2077 or Ubisoft’s Watch Dogs: Legion on a GeForce RTX GPU. As an additional feature, ReBLUR denoises ambient and specular occlusion signals for free, what can be useful in modern games.

SIGMA is a fast shadow denoiser. It supports shadows from any type of light sources, like sun and local lights. SIGMA relies more on physically based spatial filtering than temporal filtering, offering minimal temporal lag.

ReLAX is a variant of SVGF optimized for denoising raytraced specular and diffuse signals generated by RTX Direct Illumination. ReLAX offers substantial improvements to image quality and performance over stock SVGF. Not only does ReLAX preserve lighting details produced by massive RTXDI light counts but it also yields better temporal stability and remains responsive to changing lighting conditions. And while image quality improvements of this magnitude are usually accompanied by a drop in performance, ReLAX is in fact 50% faster than baseline SVGF.

The left image is the denoised with ReBLUR. The right image is denoised with ReLAX with RTXDI.

Supported Denoising Signal Types


Scattered lighting reflected in all directions (with some exceptions can be called "view independent", prevails on dielectric materials). The algorithm uses hit distance to guide the denoising process, it allows to denoise ambient occlusion together with diffuse radiance for free.

Specular or Reflections

Lighting reflected in a particular direction or cone (view dependent, prevails on metals). The algorithm uses hit distance to guide the denoising process, it allows to denoise specular occlusion together with specular radiance for free.

Infinite Light Source Shadows

Sun or any other infinite light source visibility information (shadow).

Customer Testimonials

"Every developer adding ray tracing to their game needs a denoiser that runs fast and generates an excellent image. We’ve been really pleased with NVIDIA’s solution; it allows us to make the very best of our ray budget, delivering exceptional quality without compromising performance.”

Zurab Abelashvili, 3D Programmer
Ubisoft Kyiv

“We use NRD for RT bounced diffuse lighting and shadows denoising with success. Thanks to NRD, we significantly reduced the amount of rays used by our RT implementation without quality loss. It's easy to integrate and brings both, great quality and performance at the same time."

Tomasz Szalkowski, Rendering Director Techland

Additional Resources

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 A: NVIDIA Real-Time Denoisers is a software development kit for denoising of certain types of signals, produced by any form of ray tracing (including screen space tracing). NRD doesn’t use any graphics API under the hood. It contains only high level logic and precompiled shaders for several graphics APIs.

 A: As of v.2.9, standalone Ambient Occlusion and Specular Occlusion denoisers have been add to the NRD library.

 A: No. NVIDIA Real-Time Denoisers is currently based on compute shaders.

 A: The NVIDIA Real-Time Denoisers SDK is a full source distribution. SDK users receive the complete C++ and HLSL source code of the SDK, documentation, the full source code of the optional integration layer and the full source of a sample application that demonstrates how to use the SDK.

 A: NVIDIA Real-Time Denoisers has built-in shaders for DX11 (DXBC), DX12 (DXIL) and VULKAN (SPIRV).

 A: The NVIDIA Real-Time Denoisers SDK is now available to selected developers who are part of the GameWorks Organization.

 A: NVIDIA Real-Time Denoisers is available in our custom NVIDIA RTX branch of Unreal Engine 4. There is no support for NRD in Unity at this time.

 A: Yes, we are currently exploring options for integrating NRD into Unity. Please stay tuned for further updates.

 A: The NVIDIA Real-Time Denoisers SDK can denoise three types of signals. Diffuse (including ambient occlusion), Specular (including specular occlusion) and Shadows from an infinite light source.

 A: Yes. NRD supports checkerboard mode (0.5rpp) if a smaller number of rays per pixel is needed.

 A: In addition to the noisy input (diffuse, specular and/or shadows) it’s regular parts of the g-buffer:

  • Motion vectors for primary rays (surface motion)
  • Normals
  • Roughness (for specular)
  • Z-buffer

 A: ReBLUR is designed to deliver high quality denoising with low ray budgets delivering optimal realtime performance. It also supports checkerboard rendering that results in performance that is >50% faster than SVGF and roughly 15% faster than ReLAX in ideal scenarios.

 A: ReLAX is designed to deliver the best image quality for applications with a higher density of rays in a scene like those leveraging Nvidia’s RTX Direct Illumination lighting. In these cases, ReLAX will deliver superior denoising quality when compared to SVGF and ReBLUR.

 A: Yes, it is possible to use both denoisers together. If ray traced signal consists of some separate components (like, direct and indirect, or low RPP and high RPP signals), you can choose which denoiser to apply depending on your preferences (blurriness, laginess, or cleanness of the output).

 A: Yes, SIGMA can be used to compliment ReBLUR or ReLAX by delivering optimal shadow denoising in a scene.

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