What are some of the challenges of Offline Rendering? I know one problem that is faced is performance and rendering times, are there any more issues?
Path Traced photos seem to have reached the point where it is hard to distinguish a CGI image in comparison to a real photo so being able to render a photo-realistic image doesn't really seem like a challenge anymore.
Is offline rendering just about refining current techniques to find an improvement in render times now and not so much about photo realism?
(Grand Moff Tarkin in Star Wars: Rogue One was entirely created through CGI since the actual actor had died)