Does 3D Make Your Head Happy Or Ache? 281
MojoKid writes "Nintendo has quasi-acknowledged that its 3DS can cause headaches and should not be used by children under 7. The glasses-free 3D handheld gaming device launched this week. Meanwhile, new research commissioned by the Blu-ray Disc Association is trying to improve the health image of 3D. Its research shows that the brain is more attentive when watching a 3D movie than when watching HD or SDTV, making the movie a more pleasurable experience. The issue, doctors say, is that 3D works by tricking the brain into making you think you are physically moving in relation to your surroundings. But you aren't. So your inner ear is not experiencing the movement that corresponds to what the eyes are seeing. This doesn't normally happen in real life. No one would deny that 3D is more immersive; that's why people like it, particularly for gaming. But the question is ... does the brain love 3D or not? Answer: not really."
Re:But... How? (Score:5, Informative)
It's a parallax barrier display. http://en.wikipedia.org/wiki/Parallax_barrier [wikipedia.org]
It's possible because Nintendo have a very good idea at what range and angle you'll be viewing the display.
Re:No one? (Score:4, Informative)
1. Focal depth: based on how much the eye has to focus
2. Convergence: based on the slight differences in pointing of the two eyes
3. Stereoscopy: based on the slight differences between the left and right image
4. Parallax: the different displacements/motions of objects at different distances
5. Visual inference: reconstructing using cues like occlusion, lighting, etc.
When you watch a normal 2D movie, 1, 2, 3, and 4 don't work. So your brain relies entirely on #5. This turns out to work remarkably well, because our brains are quite good at inferring and guessing what the real 3D scene looks like. (For instance, whenever looking at faraway objects, this is pretty much all you have to work with.) Move-makers have also learned how to best frame shots to make things look 'right'. And at least 1, 2, and 3 agree with each other, so your eyes can simply focus on the theater's screen (it also helps that the screen is far away).
The various versions of "3D" try to trick you, but unfortunately they don't hit all 5 of the above and so this confuses your brain. A typical 'glasses' setup tricks you using #3, but now the position of objects as determined by #3 doesn't match 1 or 2, so your brain gets confused (tiredness and headaches ensue). And try as it might, it can't compensate (e.g. no matter how hard it tries, it can't bring out-of-focus things into focus). Really bad 3D (where things 'jump out' at you and whatnot) can even violate #5. Ultimately your brain isn't happy because half the signals are saying one thing (distance to the theater screen) and the other half are saying something else (object really close to you!).
Nintendo's 3DS apparently tries to use parallax to fool your brain, but again the effect won't be perfect, so your brain will be unhappy.
To be truly 3D, you would need to record, and then reproduce/project, the entire waveform (e.g. collect light from every angle impinging on your camera 'screen'). In principle holography can do this, but in practice we don't have good technology. Besides, this causes many other problems (e.g. every person in a theater sees a slightly different angle, that's not necessarily desirable). True 3D isn't going to be technologically feasible anytime soon. In the meantime, we will have only approximate 3D solutions... which it seems are actually worse than just allowing the person's brain to fill in the blanks.