Denoising is another good practical application of AI in 3D, you can save a lot of time without giving up any control by rendering an almost noise-free image and then letting a neural network clean it up. Intel did some good work there with their open source OIDN library, but then genAI took over and now all the research focus is on trying to completely replace precise 3D rendering workflows with diffusion slot machines, rather than continuing to develop smarter AI denoisers.