1.2 NVIDIA AI Denoiser
The NVIDIA AI Denoiser uses artificial intelligence to guess what the image should look like without the noise. It does it really fast and that's why it is great for look development.
To use it simply add a V-Ray Denoiser render element and choose NVIDIA AI Denoiser.
(Keep in mind that it only works with NVIDIA GPUs)
In V-Ray Settings tab you can set the “Post effects rate” to 100. This way you'll be working in real time.
Since it is recommended for look dev only, you should use it with IPR.
You can now apply materials to your liking.
Right click on an object in the render and get its material to edit it.
Since, the NVIDIA AI denoiser is only guessing what your image should look like, it doesn’t provide 100% physically correct result. The reason is that it gives slightly different result each time you render. It also doesn’t work well for animations and scenes with lens effects from the VFB. That's why when you are ready with setting up your image revert the “VRayDenoiser” render element back to the “Default V-Ray denoiser” for final frame rendering.