While 3D-enabled TVs dominated the Consumer Electronics Show, Avatar 3D ruled the box office and Nintendo just announced the newest 3D version of the DS, the reception of the resurgence of binocular 3D technology has been underwhelming.
Yes, historically this technology has been poorly implemented (anyone remember the Virtual Boy?) and many complain of the added eye strain. But the real reason nobody cares about binocular 3D is that the spatial information provided by 3D glasses is psychologically minor, like the difference between 5.1 and 7.1 surround sound systems.
When it comes to visually perceiving three dimensions, psychologists identify thirteen depth cues. Eleven of these cues are monocular, meaning they only require one eye to perceive spatiality. Because 3D glasses only add a sense of spatiality by providing different images to each eye, monocular cues are available even without 3D glasses.
This explains how people with one eye can still function successfully in a 3D world and why we have no problem perceive 3D space when watching TV or looking at a perspective painting. Humans have spent centuries perfecting the portrayal of these monocular cues from the renaissance in perspective drawing to the magic of old school computer 3D projection graphics produced by projection matrices, Z-buffers and other techniques. Needless to say, humans have already mastered the art of reproducing monocular cues well before 3D glasses.
Of the remaining two binocular cues, only one of them works with 3D glasses. The binocular depth cue “convergence” only occurs by the physical sensation of both eyes angling differently in order to focus and account for an object’s distance from the face. Since a viewer with 3D glasses is still looking at a flat screen which is a consistent distance from the retina, this cue doesn’t work with 3D glasses.
Thus, the only binocular cue that 3D glasses actually provides is stereopsis or the disparity of images on the retina due to differing viewing angles of each eyeball. This cue doesn’t function for objects that are far away as the difference in images decreases over distance. Adding one minor cue on top of 11 existing cues is not much of an improvement.
3D glasses are even worth less when we acknowledge that the main driver of 3D spatiality is the brain. Psychologists have recently placed more and more emphasis on the brain’s role in determining dimensionality – to the point that they’ve discovered that the brain fakes binocular 3D vision even for parts of the vision that are only viewable by one eye.
Add to this the fact that many precision jobs, for example threading a needle or firing a weapon accurately, are actually easier using monocular vision than binocular vision, we begin to understand why nobody much cares about 3D glasses.
Comparing binocular 3D technology to monocular 3D technology is like comparing a 12 channel surround system to an 11 channel surround system. Sure, it’s cool to geek out about the newest tech, but honestly, do you much care if you can’t much tell the difference? At best 3D glasses are a minor evolution roughly 1/12th better than monocular 3D. I’d prefer that developers spend more time on other things.