Recent advances in computation, simulation, and real-time rendering have become so advanced that some visual effects artists are opting for rendering everything with CGI instead of filming it outright. In making-off featurettes, we have seen the VFX teams scrap explosions, fluids, car crashes and actor stunts with CGI inserts that offer precise control over lighting, debris, motion, and quality which are all a crap shoot when filming with a real camera.
NVIDIA just released some demos of real-time ray tracing that surpass the best quality renderers of the 1990s with playable frame rates and ambient occlusion that in the right hands could be indistinguishable from many special effects in a film. The new RTX technology in their Volta architecture GPUs can do area shadows, true multi-level depth reflections, refraction and global illumination in real time 30+fps on a personal computer.