I thought this was only a geezer phenomenon, until I looked at the hottest spot at the moment for discussions about S3D, the developers' forum for the headset viewing device, Oculus Rift. Same old, same old, but with a cast of young people who are somewhat more polite.
For technical subjects, perhaps a new generation is better off not learning from the old. Perhaps the young are entitled to learn from their own mistakes, just like their forebears did.
Cruise online sources about stereo 3D if you suffer from insomnia. I'm up to my eyeballs with pictures of eyeballs. The "explanations" of stereo 3D tend to over-technologize stereo vision, both natural and synthetic. The thing about natural vision is, it just works, we don't need a manual to make sure it works right. The thing about synthetic stereo vision is, when it isn't done right it hurts, a terrific learning reinforcement. For this reason, common sense based on actual experience is just as important as a calculator when designing S3D.
One professional from the computer graphic side of Hollywood S3D, with whom I've conversed, seems to take a seat-of-the-pants approach. He tests various settings on a big screen with his in-house cohorts and notes for extreme settings the number of yelps. (People who work with S3D are just as sensitive to eyeball pain as anyone else.) In this way, one CG stereo designer with an animation studio gets a good feeling for how far to push the envelope.
I like this bold but viewer centric approach to S3D design. It leads to experience-based conclusions that old timers and newbies often miss, or misstate.
First of all, you CAN go to infinity and beyond. The traditional wisdom is that the on-screen separation of right and left points should never exceed the separation of your two eyes, which together gaze into infinity along parallel lines of sight. Regard this constraint as you would regard the speed limit on Highway 50 across Nevada: advisory, use discretion. Discretion is well advised by one's own awareness of what is actually happening. We can accept divergence, seeing "beyond infinity," but within limits and only for a while.
Next time you watch a 3D IMAX production, remove your 3D glasses to see to what extent distant objects are separated on the screen. In many cases, the separation is noticeably further apart than the separation of our eyes, which means our eyeballs are diverging from parallel alignment when we try to fuse right and left. But this doesn't happen for long, and it doesn't happen where our eyes are attracted to the main action in the scene. So divergence isn't a problem when used with discretion.
Second, the volume in front of the screen is the spatial bonanza zone for depth perception. The conventional constraint that a scene should stay mostly behind the stereo window frame deprives the stereo designer of the most valuable real estate. Our natural stereo perception is optimized for discerning depth at close range, and the stereo designer can show more roundness for close objects that extend from the screen into the theater.
The next time you view an animated stereo 3D movie in a theater and the scene shows a medium or close up shot of the characters, glance to the vertical edges of the frame to gauge your distance to the screen. You will notice that the characters are well in front of the screen, and that their shapes are nicely rounded. You will also notice that you wouldn't have noticed if you hadn't glanced away from the center of attention.
As a new generation teaches itself stereo 3D, my advice is this: You can trust what you see if you take care to notice what you see. As an audience member or as a practitioner, don't be intimidated by confusing explanations, but rather, be empirically guided by what actually works and what actually fails to work. There's truth behind the doctrines, but you have to find that out for yourself. In so doing, you may discover new truths.
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