Hello Unreal Engine Team,
First off, thank you for the amazing strides the rendering team has made in light transport. Lumen is a remarkable tool and a truly transformational thing. The path-tracer has incredible quality and performance as well, and I wanted to offer a few suggestions that may improve its’ versatility.
To my knowledge, you have already implemented reservoir sampling, spacial and temporal denoising, and several other cutting-edge features for PT performance. I was wondering if you’d consider developing an in-house denoiser that ran on the GPU, as I’ve had several stutters and irregular performance behaviors (and an occasional crash), as the image hitches to denoise on the CPU. Something like ReBlur/ReLax would be ideal, but I’m unsure what the ownership policies are on the technology as it was developed by Nvidia.
Furthermore, the denoiser tends to wipe out texture detail. I like what games like Minecraft RTX have done, where they’ve removed the albedo, denoised, and reapplied it in a post pass to achieve a clean resolve. Furthermore, they have performance levers such as forcing materials to lambertian after the first bounce.
From what I’ve seen, the industry is moving in the direction of real-time path-tracing as the technology has gotten more efficient. I believe engineering in engine support for path-tracing designed for eventual real-time use would be very good.