The eyeball-half-nelsoning does occur, but only in films where the 3D has been executed badly. It is perfectly possible to cause significant pain to someone watching a film in 3D, but there is no excuse for it, either in native or post-conversion. Well-designed, -considered and -created 3D will not cause eye fatigue. The amount of work that you are asking the audience’s eyes to do is very moderate, and part of the skill of those involved is in creating a good 3D feel to the film without causing eyestrain. It has partly been that desire to avoid eyestrain, though, that has resulted in a lot of 3D films being remarkably flat and destroyed any potential that could have been gained from shooting the film in stereo.
This tendency comes from something else as well — and Chris Nolan alluded to it when he said, “The whole idea of film is that it’s three-dimensional on a two-dimensional plane.” Directors and cinematographers are very skilled at shooting 2D films with real depth. Many of the techniques that they use are designed to do exactly this. When you then add this stereoscopic depth on top, it appears unnecessary and false – after all, it wasn’t flat before, so why add something that isn’t needed?
This leads to a tendency to avoid anything more than a minimal amount of depth, and more importantly, to avoid stereoscopic roundness. This is the sort of depth that makes a human face feel rounded and correctly proportioned and is the opposite of the cardboarded 3D that we often see. Give it a little too much depth, though, and you go from something beautiful and sculptural to something distorted and ugly. This is exacerbated by the fact that in order to achieve that optimum roundness, you need to design the scene, the lighting, the blocking, the framing and the acting to enable it to happen without causing the eyeball-half-nelsoning that Rian talks about. This results in films shooting 3D that avoid any chance of achieving the moving sculpture of Scorsese’s talk.
Even in its current form, though — with the glasses, poor projection, risk of pain and dilution of the shared experience — there is a lot that 3D can be used for to genuinely help the director communicate with the audience, which at the end of the day has to be the goal of any element of the filmmaking process. Between the two films that I am currently in post-production on, we are using the 3D variously to add a sense of scale to the bad guys, to give a sense of claustrophobia to the homes of the good guys and to differentiate subconsciously between the two. We are using it to help build the sense of safety and cocooning when the protagonist is safe and the sense of isolation when she isn’t, and we are using it to give an otherworldly feel to a dream sequence. We are even using 3D to help add impact to a moment of shock — not by boosting the shock but by relaxing the audience in the lead-up to the moment so that the shock hits harder.
The future of cinema might be 3D, but as Rian says, it has a way to evolve before it gets there. That evolution may well take us past stereo to other 3D viewing-capture and display methods. I would suggest, however, that by using the current medium effectively, imaginatively and intelligently we have a long way to go before we have even caught up with the creative potential of existing technology, let alone the musings of Scorsese and Johnson.