UKC

One of my eyes has perfect vision, the other is very poor causing my brain to ignore signals from it, meaning that even the use of glasses is pointless… When I watch 3D films, I can see the things appear out of the screen so assumed I was seeing what I was meant to see. I tested to see if my bad eye had any effect and closed it for a while and found no difference. Does the new 3D system using the polarised lenses work with one eye, or am I not seeing what I should be seeing?

In reply to David Barratt:

You're seeing something very odd. Were you on drugs?

There's no way anyone can make 3D films for cyclopses or amblyopes, the whole principle of 3D film is showing two slightly different images to the two eyes and the brain inferring depth. I'd love to be wrong, and I'd also love to know what the 3D thing you saw with only your good eye looked like, but on that point I'll never know!

In reply to Jon Stewart:

Not all visual cues for depth perception are binocular, many are monocular (particularly with perception of depth more than about 50m away) based on relative movement and things like that. Therefore the brain can infer depth without binocular vision. I expect if you have very poor vision in one eye the brain will adapt to put more weight on monocular cues.

I guess the OP believed the film to be 3D and so perceived it in 3D. If you only have one useful eye and didn't notice a difference when the other eye was closed then all the stuff coming out of the screen was from your own brain, not the polarised light technology.

In reply to Jon Stewart:

Been discussing this all day with the family. I'm sure I can see a difference between a 3D and a 2D film. Nothing's ever that amazing but I can tell when stuff is moving towards me, more so than in a 2D… I think. I definitely remember seeing the pixar mini-film before Toy Story 3 (http://www.youtube.com/watch?v=XpcHnVRtujM) and 3D effect was clear. The black was in front and you were looking through...

In reply to splat2million:

Interesting… So I could legitimately see more in a 2D than in a 3D, but just not as much as I am meant to see? Now I'm really curious to know what everyone sees!

In reply to David Barratt:

It's probably that although one of your eyes vision is very poor, your brain has adapted well to using poor stimulus from it to perceive depth, filling in the detail from the other eye. You should be able to perceive depth from a 3D film in a pretty similar way to you perceive depth in real life. The brain is good at this sort of adaptation.

If you were to cover one eye, the film should appear exactly as a 2D film (this would also apply to someone with normal binocular vision)

In reply to splat2million:

Had a go at this as a test ( http://www.mediacollege.com/3d/depth-perception/test.html )

Step one fails completely, I can only see a finger on the left.
Step two works fine.

I've never been aware of any issues other than crap vision in one eye, but maybe haven't known what to look out for!

I think I can climb and belay in 2D then… go me!

In reply to David Barratt:

Relative size on screen may account for much of it. As in:
youtube.com/watch?v=vh5kZ4uIUC0&

In reply to splat2million:

Thing is, the monocular cues in a 3d film are no different to normal films. What is different though is that without the Polaroid filters, one eye is seeing 2 slightly different images on top of each other. If the op can infer depth from that, he has a special brain: the wiring would have to be completely different to normal steriopsis.

In reply to David Barratt:

Timely post - I have a weak left eye (amblyopia since birth, Drs attempted treatment when young but unsuccessful). I have always thought that it could not be treated. Recent research may indicate otherwise.

If you want to know what a person with 2D vision experiences when they learn to see in 3D, this is very interesting reading -
http://www.amazon.co.uk/Fixing-My-Gaze-Scientists-Dimensions/dp/0465020739/...

and lots of recent research papers, an example -
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1994076/

Off to see an Optometrist / vision therapist on Friday. Dunno if this will work but it's worth a flipping good try!

Paul

In reply to Paul Evans:

Thanks, I'll definetly have a read of that. Drs tried to fix my eye when I was younger, but no success. opticains never have any suggestions other than "well you could try glasses again, but it probably won't work..."

In reply to David Barratt:

I have the same. One good eye and one fairly useless orb. I have never had a problem judging where a hold is or hitting a moving target at martial arts or riding motorbikes. Once I went on a course to look at stereoscopic photos and of course I couldn't see the 3D effect. The instructor spent the rest of the weekend course trying to figure out exactly what I saw!

In reply to ring ouzel: Just to add to the confusion, my Grandad had one good eye and one glass eye, yet he could view those autostereogram pictures and tell you what the image was quite easily!

In reply to owlart:

I've never understood those pictures. looked at them for hours when I was younger and couldn't see anything. sure your grandad didn't cheat and look at the answers in the back? (I used to !) But syaing that, I'm still convinced I see more than I see in a 2D film when in a 3D film with one eye closed.

In reply to David Barratt:

I suspect the way many '3d' films are made up digitally from 2d film using discrete layers which are then spatially shifted and scaled gives a pretty strong 3d effect just from the parallax and scaling even before the images are split into left-eye and right-eye polarized versions to further enhance their appearance of depth.

Do you get the same illusion with film that has actually been shot 'in 3d' effectively with two cameras?

You see the effect quite often used on TV where old photographs are stripped apart into layers then the viewing angle and zoom is changed giving quite a strong and convincing illusion of depth to what is clearly an old photograph rendered on a simple flat display.

jk

In reply to David Barratt:


I haven't watched much in the way of 3D films, but I think they may be shot (or rendered) with a reduced depth of field compared to 2D films. That forces you to concentrate your attention on one "depth" in the scene, and when they vary the focal distance to shift your attention to different distances in the scene (which would be accompanied by changing the "3D-ness" presented to your two eyes if you could see that...), you would probably perceive that as a 3D effect seen even with just one eye.

In reply to David Barratt:

I used to have 20:20 vision, but then got kicked in the head a few times by some lovely chap that left me with next to no depth perception, regularly pouring water from the kettle next to my mug etc. Over a while it seems to have improved a bit but 3D films are completely useless, although I was in a TV shop a few months back and they had this new fancy 3D TV, felt like I could walk around inside it which is more than I could say for the rest of the shop! That was without glasses so I assume all in the filming.

In reply to owlart:

He was having you on. It is impossible to see an autostereogram with one eye (without magic/lying).

In reply to jonny taylor:

Yes, interesting point. Not the same kind of 3d effect you get from using both eyes, I doubt it could be made to make things 'come out of the screen'.

In reply to David Barratt:

Does anyone actually know how the current generation of 3D glasses works? The old ones were red/green-based but presumably now it's done by polarisation.

In reply to Dave Garnett:

There are apparently two methods, each using polarisation. One splits each frame into two images with every second line being for left/right, the other is every second frame. Apparently the hobbit works well because it has double the frame rate and therefore by using every second frame, each eye recieves the normal frame rate... that makes some sense to me, but I'm just trying to remember what I was told.

In reply to Jon Stewart:


I don't know... possibly not. The brain is remarkably good at "completing the story" given partial information though. If the visual cues are consistent with your attention (and optical focus) following an object that is moving towards you, it wouldn't surprise me if the brain did perceive that as "coming out of the screen"...

In reply to David Barratt:

OK, so that sounds as though it's perfectly possible to to see a 3D image with one eye. I know that's not how parallax/depth perception normally works but the visual cortex is a complicated and interesting bit of processing.

Anyway, it's an easy experiment to do and I'll try to remember next time I have the opportunity).

In reply to 65m moderate millington:


This is the kind of thing I thought was symptomatic of depth perception issues. I've never had those kind of problems so assumed I was fine, I guess the bad eye is either doing just enough, or my brain and good eye have learned over the last 20+ years to cope. If 3D cinema and autostereograms are the sum of my 'disability' I guess I can count my self quite fortunate! First world problems and all of that...

In reply to Dave Garnett:

No, i don't think you've understood David Barratt correctly - unless I've misunderstood it, both systems require both eyes. (Every other line on each video 'frame', or every other frame, is left/right.) Each eye sees the 'correct' perspective for its eye position, and so the stereoscopic vision is formed. I can confirm, as someone who has a defective eye after a car crash, that I cannot see 3D movies with my one-good-eye condition. I went to see Gravity with the fantasy that it might work, and it didn't. It was actually a bit more of a strain on the eyes than usual because I had to keep the glasses on to avoid seeing the picture as a slightly double image - which is just the way a person with normal eyesight will see it if they remove the 3D glasses.

In reply to Dave Garnett:

… 3D vision in the cinema, as in real life, is done by the two eyes having a slightly different position in the head, and thus slightly different perspectives. The brain does the 'triangulation'.

In reply to Gordon Stainforth:

Yes, that is what I meant, thanks. This was all sparked by seeing Gravity actually. Good film if you know nothing about physics or the geography of space! I think having never experienced true stereo vision, what I have been interpretting as 3D is probably not 3D.

In reply to David Barratt:



What about chucking spears at woolly mammoths?

In reply to Gordon Stainforth:


Not quite, I am blind in one eye but used to have both.

I can't see 3D cinema but I have no problem with the real world.

As I used to have 2 good eyes and use 3D photos a lot (In stereoscopes for mapmaking) and remember what they look like, I can say that owlart's grandfather was pulling his leg!

In reply to rogerwebb:

Exactly, monocular cues are fine for constructing a 3d percept to navigate the world with, but if you want to trick the brain into perceiving a patently 2d object such as a screen as 3d you need stereopsis. Monocular cues (eg reduced depth of field) aren't sufficient.

In reply to rogerwebb:

Well, I have no problem with seeing the real world with my one good eye, but I can't see it in 3D. At medium distance I'm seeing the world in a kind of poor 3D with double vision; infinity is fine in 1D. Close up I can't judge distances at all accurately (this is a serious problem when climbing/scrambling/ and pouring wine into wine glasses!). When I read, I'm doing so in 1D with my good eye.

In reply to Jon Stewart:


Yes - that's quite a good description of what I'm doing when I perceive the world now, but no way is it proper 3D.

In reply to David Barratt:

I cant see 3d films, the glasses use polarised lenses. With the glasses on I see one of the two images. With them off I see both, it looks like double vision to me.

If they dont use polarised lenses, I would like to know how they do it.

In reply to Gordon Stainforth:

To be fair I have a similar problem close up (pouring is a problem,)but for climbing I have found that if I move my head, it usually sorts out (especially if I leave a hand in sight).
I am close to convinced that the distance eyes are set apart is insufficient to give any meaningful triangulation effect at distance, consider an optical rangefinder. I'm also sure I see in 3D else how can I catch a ball?
Having said that all people are different and maybe I am lucky.
Do you have no sight in your bad eye or do you have vestigial sight? I was wondering if the brain might get confused if you have some left, whereas mine is most definitively working with one only.

In reply to rogerwebb:


My mum keeps hawks, and to focus they move their head about to change the perspective. Sounds similar to your solution. My brain just ignores the bad eye so even with a lens infront, I just see blurs, I don't think I get confused, but who knows.

In reply to rogerwebb:





I'm afraid your conviction is incorrect. The distance the eyes are set apart is exactly how our 3D vision system works … and why, as we focus on objects between hyperfocal point and infinity we are seeing them, for all intents and purposes in 1D (Which is why, when you look down the Troll Wall in Norway, the very steep screes at the bottom actually look flat, like a carpet.)

It's how a 3D camera works to, with lenses that exactly imitate the human eye, set 2.5 inches apart.

Pics here of two typical cameras:

http://www.stereo3d.com/vidrec.htm
http://realvision.ae/blog/2010/07/manufacturing-the-perfect-3d-camera-or-3d...

Article here:

http://en.wikipedia.org/wiki/IMAX#IMAX_3D

http://www.stereo3d.com/vidrec.htm
http://realvision.ae/blog/2010/07/manufacturing-the-perfect-3d-camera-or-3d...

In reply to rogerwebb:



The threshold for detecting retinal disparity between the two eyes (the angular difference in where the image of the same object falls) is around 30 second of arc for someone with good stereopsis. So at 20m distance if two objects are 1m apart in depth you can get depth info this way, according to my little sketch. Beyond this sort of scale it's all about parallax, lines of perspective, texture getting finer into the distance, relative size of objects ("small...far away" if you know what I'm referring to).


Monocular cues are fine for predicting a trajectory, I think the info from stereopsis is redundant in that task.

In reply to Gordon Stainforth:


At short range, yes.



And has the same range restriction.

I think that most depth perception as Jon Stewart says is down to visual clue, I expressed myself badly in saying I had 3D vision, what I mean is I have as good depth perception (most of the time) as when I had two eyes

In reply to Gordon Stainforth:

I'm getting confused now! I was remembering using old style photogrammetric machines in the early 80s and how they gave a very weird 3D image of landscape, the photos having been taken from several thousand feet, which was not at all like looking down from an aeroplane. At the same time I remember an effect like your Troll Wall one, when having two eyes I was unable to determine how far away an object was on an ice shelf (all white view) until able to identify it, at which point range was obvious.

I think I will stop thinking about this in case my world suddenly goes flat!

In reply to Gordon Stainforth:

I agree that this how it's normally done, I was trying to be too clever by three-quarters by working out a way two different parallax images could be delivered to the same eye by different polarisations.

Actually I'm not sure polarisation is what I mean. What you need to do is encode two moving parallax images in the form of a sequence of two 'stripey' images and presented in a rapidly alternating fashion to non-overlapping stripes of the retina. Not quite aure what would happen but it's just possible that this would be decoded as a 3D image.

Or a migraine.

In reply to Dave Garnett:




The polarisation is the modern way of separating the left and right images, with their different perspectives. Has huge advantage over earlier coloured lens systems of not being affected by forms of colour blindness.

The stripey thing is exactly how an old fashioned cathode ray telly worked, doing alternate lines every 50th of a second to make one stripey frame every 50th of a second (on UK 50 cycle PAL system) Then there was a 'blanking pulse' - black screen - while the cathode ray beam shot from bottom right to top left of screen to start the next frame, when it would do the other alternate lines. This was exactly the same principle as an old-fashioned (pre-digital video) movie projector, in which each frame was presented to the human eye as a static image every 1/24 of a second … but, in fact you only saw it for 1/48th of a second, and then there was a 1/48th of a second of black (done typically with a rotary shutter) while the next frame was being pulled down and locked into position. How many people, when they went to the cinema, ever realised that they were in fact watching a black screen for half the time they were watching the movie? Just the same on an old fashioned telly. I think the modern digital system is completely different, with a far faster cycling rate, but not quite sure about this (only because I haven't bothered to find out). It still all depends on that fascinating natural phenomenon of the human eye, 'persistence of vision', without which neither film nor television would be possible, because it can't see those black frames. This only works down to about a 1/16th of a second, below which it starts to flicker. Early movies went at an 1/18th sec and were just about OK, but at the later 1/24th sec (and 1/25th on telly) the illusion became perfect.

In reply to Dave Garnett:

when I said 'coloured lens systems' I meant 'coloured filter systems', obviously.

In reply to Gordon Stainforth:

The reality is we don't know yet to what extent depth perception and 3D perception might be possible for those with monocular vision. I don't know anything about the 3D glasses and how they work. But Jon is right to say that your brain can use visual cues to create depth perception. See the following for example:
http://www.nature.com/nature/journal/v452/n7187/abs/nature06814.html
http://go.nature.com/OIargR
Movement of both the head, and eye, are thought to be important in depth perception, in which case, it is quite east to see how existing neural pathways could be emphasised to take greater account of movement dependent depth perception in creating an overall sense of depth, especially when neural development has occurred in someone with monocular vision. Often in films the camera is not static, but it motion. It is well known that people watching films (or using a microscope) can take a camera eye view (or objective eye view respectively), i.e. the cinema / room would disappear (or microscope would disappear) in the perception of the user. So it is conceivable that camera movement on film would also provide sufficient information for the brain to assume movement is real and use that information for creating depth perception. £D sound information is another cue which is likely to be used to enhance the perception of visual depth (remembering that such "perception" is not a phenomenon of the eye, but uses signals derived from the retina that are integrated with many other neuronal signals (e.g. involving information about head movement, as well as learned knowledge about absolute object sizes and normal spacial behaviour of objects / geometry.. ..sound is another signal that I would doubt the brain is unlikely to utilise.

well nobody's mentioned the pulfrich effect which can also be used with super careful filming to create 3D on a 2D screen (need light/dark glasses)

in fact interposition (one thing in front of another) is the biggest depth cue and overrides most others.

http://go.nature.com/OIargR -> this uses/integrates disparities, ie from stereo, 2 eyes