Path-based Monte Carlo Denoising Using a Three-Scale Neural Network

Monte Carlo rendering is widely used in the movie industry. Since it is costly to produce noise-free results directly, MonteCarlo denoising is often applied as a post-process. Recently, deep learning methods have been successfully leveraged in MonteCarlo denoising. They are able to produce high quality denoised results, even with very low sample rate, e.g. 4 spp (sample per pixel). However, for difficult scene configurations, some details could be blurred in the denoised results. In this paper, we aim at preserving more details from inputs rendered with low spp. We propose a novel denoising pipeline that handles three-scale features - pixel, sample and path - to preserve sharp details, uses an improved Res2Net feature extractor to reduce the network parameters and a smooth feature attention mechanism to remove low-frequency splotches. As a result, our method achieves higher denoising quality and preserves better details than the previous methods.