Originally Posted by dovercat
Problem is it is not just like the way you see 3D in everyday life, your brain does not see 3D from a pair of 2D images coming into each of your eyes.
Eyes have lenses and depth of focus, studys on reliably predicting object distance with binocular and monocular vision seem to show that the binocular vision is not the only and maybe not the main method used by the brain to figure out accurate object distance, beyond objects right next to you. Visual acuity detail resolution by focus distance of the eye might be an important factor.
Also the irises and head can move. Most 3D displays only use two fixed viewpoints one for each eye, with no head tracking.
Field of view is also alot bigger than with most displays, the real world does not appear in a little window in the middle of your field of vision like a relatively small display. This is particularly bad at emulating believable motion as peripheral vision is more motion sensitive.
You're right that focal-distance is also another cue that the brain uses to perceive depth.
Of course, focal distance is also lacking in conventional 2D moving images.
Head movement can also affect depth perception (as it also affects 360 degree sound perception) but most move viewers say seated with relatively little head movement during 3D films.
The bottom line is that we see 3D from the two different images coming into our two different eyes... and in real life we have focal distance as a further assist to that perception. However, since people *do* see 3D imagery even with flat left/right 2D images, 3D perception, in large part, does work with discrete left/right pictures. Two channel 3D video is the best we can do right now given current technology, and it works exceedingly well when done properly. I still enjoy my 3D stereoscope cards with my Victorian stereo-viewer despite the fact that the images themselves only allow a single point of focus... the 3D effect can be stunning and comfortable on the eyes once one gets adjusted.
I agree that the larger the image the better... the more field of vision that's affected the better for 3D. Of course, that's generally true of the film genre, which is why movie theater screens typically offer an 30 degree viewing angle for their center rows. if high-end movie reproduction is anyone's goal, I'd highly recommend a display system capable of delivering a wide-angle experience that properly fills ones field of vision, in a darkened room to minimize the distraction of the surrounding environment. That also happens to be an ideal way to view 3D content.
Convergence without accomodation and movement parallax is not how the you see the real 3D world. They still have a way to go before it is a perfect emulation of reality. But it only needs to be good enough for the eyes/brain to figure out, as they want you to be able to comprehend your surroundings.
For moving points of view they would also have to trick the inner ear into beleving you were moving.
Agreed. I'd never suggest that twin 1080 x 1020 images encapsulate the full gamete of what's possible for human perception. The current method, for most viewers, is enough "for the eyes/brain to figure out", though I'd welcome continued technology improvement at any time, for all video and audio reproduction issues.