There has recently been a bunch of work towards progressive photo-realistic global illumination in WebGL. The best example I've seen of this is https://cl3ver.com renderer. There is some overlap between this and the high end rendering that Octane and other photorealistic GPU renderers do. I think it is time to add this to Three.JS.

This is a meta-task that describes what needs to be done (this is in the spirit of the PBR meta task from 2015: #5847)

The main components of this approach would be:

Temporal Reprojection Anti-Aliasing
#14050

Progressive Global Illumination via Instant Radiosity/Virtual Point Lights
#14047

Progressive Soft Shadows via Light Source Sampling
#14048

Screen-space Reflections
#8248