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Old 09-16-2020, 04:13 PM   #161
globalimages globalimages is offline
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Sorry to say, but just don't bother with glasses-free 3D in the sense we all want: a cheap-enough "device" similar to a (TV or projection) screen in which a group of people (without too much constrain) can simultaneously watch a "natural" (i.e. not only CGI) moving scene in "near perfect" stereoscopic glory (one separate view per eye corresponding to aprox. say 7cm of inter-axial distance).

3D film technology has existed for about 100 years and this "problem" hasn't been solved because, well, it "can't be solved".

Or rather, the only way to solve it is:

A) Either somehow track where all the eyes of all the people watching are with respect to the "screen" and somehow shoot the appropriate view to each one (still some could overlap, like someone sitting in a sweetspot behind another person with the "wrong" eye in that area)

or

B) Use any of different methods to fill a certain viewing angle in front of the "screen" with multiple views appropriately separated horizontally so people within this area get the corresponding image-per-eye. Well, for this system, you need basically a view per each "aprox" 6cm of space (the space between the eyes) of the end of the area "cone" you want to fill for different viewers, that is, you need many, many, many views, the more the better (to a point). Thus you have to capture, edit, transmit, etc all those views, or use powerful processing to try to do "fake 3D" and interpolate artificially generated extra views between those you captured and those you are displaying.

You want to do this right? You need as many view pairs as (aprox) 6cm of space "slots" you want to fill in the room. Even if you interpolate, that means 3 views better than 2, 4 better than 3 and, well, to be realistic, you better use at least 5 to 25 views (or equivalent lightfield ray direction information). So the capture "resolution" (number of pixels or views) and bandwidth needed for the transmission of all this information is, well, say 5 to 200 times higher than we are using today. If you think using 2 cameras to capture 3D is a hassle, just ask cinematographers to use the equivalent to an array of say 5 (6, 7 ... 25) cameras, the more the better, or equivalent "distance" holographic (or light field) sensor device (a VERY large "sensor", we are talking >1meter long sensors/array of sensors/array of cameras if we want to do it right).

So yeah, besides pure CGI content (which can generate the necessary large number of views "on the fly" with a powerful enough GPU), natural-looking stereoscopic (different view to each eye) images just can not be shown to an unrestricted group of people spread in the space in front of a "device" without filling such space with as many corresponding views as "slots of eye-pairs" are in such space, be this "pair of images" reconstructed by a lightfield or discretely in vertical slices ...

So in short: it's never going to happen, until it becomes cheap enough to film with a minimum of say "5 cameras" and to store/transmit the information equivalent to "say 5 images" PLUS equip a powerful GPU at the display-end able to extrapolate those (say) 5 views into (say) 20 "fake-but-good-enough" views needed ... And still the field of view of such a display would still be a bit limited and/or a few positions in front of it would not work (easy to fix, just move your head a bit to the left or the right, or a bit closer to/farther from the display).

This is physics, there is no way around it. It's been researched for 100 years since the first 3D film and we still don't have glasses-free 3D displays of any kind (to the "good enough" level that we want). Before you say we have holograms that are close enough, just think of the amount of information a hologram contains (to transmit it per second to form moving images) and that it's also a bit limited in viewing angle, size, etc.

CGI scenes: not too much of a problem, the information needed to transmit is small, powerful renderers could make multiple views at the display end. Natural scenes: well, the more views (pixels) you can capture the better, a few in-between could also be artificially fake-3D rendered, much like the 3D-conversions done today on most 3D films. Compression can be used: just send a "large background image", all necessary "textures" and a depth map and have a processor figure out multiviews (mostly what has been done up til now with lenticular TV displays and similar). The results up until now: still limited in all senses (resolution, viewing angles, crosstalks). It can be done pretty good for CGI and static content though, like on these commercially available displays some 10 years old, but that's not what we are talking here, right?




Last edited by globalimages; 09-17-2020 at 11:19 AM.
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Old 09-17-2020, 07:06 AM   #162
jacQues Imperium jacQues Imperium is offline
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A lot of possibilities, but not currently a big enough market? Still, we all know in some future this will be the norm. I came across this video from early this year:
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Old 09-17-2020, 02:44 PM   #163
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Well, like said, pretty much impractical for "real life" images (non CGI) with nearly unrestricted "depth" and number of people able to watch it at the same time with little restriction on moving and position.

Commercial 3-D (stereoscopic) movie theaters without the need to use glasses have existed for >50 years (in Russia, mostly, but also France, Germany and even England), but again, this is different from a "TV-like-screen" which allows a group of people to (mostly) FREELY move in front of it and still not lose the stereoscopic view (the APPROPRIATE view to each eye). It is possible to design a movie theater with fixed seating positions and allow for a small amount of head movement/placing/sizing, since it's then possible to provide just two or three views to reach the audiences eyes (though the more views, the less restriction with head placement/movement and size, like for small children).

https://www.ina.fr/video/CAF97060248

Autostereoscopic_Cinema_History.pdf

Anything else, is just "a gimmick" like this 10y old display (8 views), or the Looking Glass mentioned above, etc. It doesn't lead to a display that allows for "almost perfect" stereoscopic viewing of "anyone just walking in front of it" unless, like I said before, eye-tracking-and-restrictions are imposed OR a (very) large number of views (which equates to large number of "pixels") are displayed (and thus, captured-or-rendered and stored/transmited etc) or we limit the content to basically CGI/rendered-on-the-fly stuff.



Last edited by globalimages; 09-18-2020 at 02:24 AM.
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Old 09-17-2020, 09:37 PM   #164
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Watching the videos it seems like everything is pushed further back on the tv screen (nice depth) to create a kind of pop out effect, but it only goes as far as where the screen is, pop outs in you face no more. still not sold on this tech.
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Old 09-17-2020, 09:59 PM   #165
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Quote:
Originally Posted by BLMN View Post
Watching the videos it seems like everything is pushed further back on the tv screen (nice depth) to create a kind of pop out effect, but it only goes as far as where the screen is, pop outs in you face no more. still not sold on this tech.
Pop-outs are just a gimmick. What a light-field camera can do that no other camera can is replicate how we humans see. Both the foreground and background are in focus at the same time: infinite depth.
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Old 09-17-2020, 11:08 PM   #166
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Well, you can with other cameras. It's called deep focus, where you have everything in focus, just not where you can change the out of focus location after the shot. That's what the Lytro cameras did was take images in a range of depth of field so you could change your focus (the shallow depth map) after the shot, but they failed to find a market for low quality, adjustable focus images. It now lives on in display tech.

But just changing the focus point alone isn't enough for good stereo images. You still need the distance of two lenses.
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Old 09-17-2020, 11:22 PM   #167
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Looking Glass, doesn't seem like it would work for stereo 3D, since it needs 45 different angles so really 45 different cameras. 3D to 45 view conversion would probably be very cardboard cutout looking.
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Old 09-17-2020, 11:42 PM   #168
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Originally Posted by tomtastic View Post
Well, you can with other cameras. It's called deep focus, where you have everything in focus, just not where you can change the out of focus location after the shot. That's what the Lytro cameras did was take images in a range of depth of field so you could change your focus (the shallow depth map) after the shot, but they failed to find a market for low quality, adjustable focus images. It now lives on in display tech.

But just changing the focus point alone isn't enough for good stereo images. You still need the distance of two lenses.
Quote:
Deep focus is normally achieved by choosing a small aperture. The aperture of a camera determines how much light enters through the lens, so achieving deep focus requires a bright scene or long exposure. Wide-angle lenses also make a larger portion of the image appear sharp.

It is also possible to achieve the illusion of deep focus with optical tricks (split-focus diopter) or by compositing two or more images together. It is the aperture of a camera lens that determines the depth of field.
Using a light-field camera, whatever you point the camera at gives you infinite focus. You are not hampered by existing light. Works in bright light and dim light.

It's not 3D as we think of it. It's real life as we see it. It's not contrived as you have to do using two cameras.
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Old 09-18-2020, 01:18 AM   #169
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Originally Posted by BLMN View Post
Watching the videos it seems like everything is pushed further back on the tv screen (nice depth) to create a kind of pop out effect, but it only goes as far as where the screen is, pop outs in you face no more. still not sold on this tech.
Oh, they can (and do) achieve "pop outs" ... the thing is, the larger the depth you want to represent, the narrower the viewing angle you should use as to not reach a point were the wrong eye sees the wrong view.

So to get CLOSE to what we are talking here of a "almost perfect glasses free 3D TV with little restrictions on spectator placement and possibility of full depth, from way out of the screen to infinity behind it", well, you need a LARGE screen the size (horizontally) of the place where the the spectators are going to be located (i.e. field of view is as close to "0" as possible, that is, you can only see correctly it if you're directly in front of it, not to the sides) and at least as many views as this horizontal screen size divided by say 2cm to accommodate for the angular difference of looking at the corners of the screen compared to the center and allow a little head movement and different head-sizes etc.

Again, not really feasible in the way we think about it, which again, is something like a "small screen" say 70" which can be seen in 3D (without much restriction in the depth, like when using stereo pairs with glasses) from just about anywhere in a say 3x3m regular size room (except too much to the side or way too close to it, like with current TV's).

With a very large screen, it sort of CAN be done, but the physics dictates that the only good solution is fill the space with billions? of light rays which, well, translate to billions of "pixels". Or increase the viewing angle but DECREASE the amount of "depth" (the disparity in the view-steropair at that spectator position). Or the resolution. Or both.

With 8k panels now more available, more pixels are available (at a higher cost to produce/store/transmit all those 8K pixels, anybody rooting for 8k blu-rays?) and thus more views are possible, thus better results like the Looking Glass above, which incidentally works "well" (with very limited depth of just a few inches infront and behind the screen being artifact-free) 'cos it's meant to be seen by only say 2-3 people looking at it from REALLY close distance and pretty much in the center ... That thing at a distance pbbly doesn't display much depth at all ... Think about it, for an object to appear at "infinity" depth, each of the views must be (about) 6cm away in the display (so your eyes are parallel), and that screen is very small in size ... Even the bigger model is just a gimmick meant to be seen from relatively close distances, by relatively few people, and with very limited depth and not-that-great resolution and not a whole lot of allowable movement/head positions before running into problems with pseudoscopy and just plain wrong stereo-information (incorrect stereo-image pair being picked by each eye).

Like I said, sorry but physics dictates that what we want, a system similar in performance to what we have now with 3-D tv/projection/cinema, which is a resolution of 2K per eye or better, which can be seen from about anywhere in the room/theater, where the 3-D "depth" and focus has no restrictions (other than the human ones) and is not too expensive, just can not be done. Not due to technology, or to cost (not really, though it's more expensive, of course) it's just that it's impractical until new films start to be recorded with (vastly) more amount of information and this information can reach the displays. Without more "views" (or light rays direction information, basically pixels, but you can call them voxels if you prefer), 3-D w/o glasses won't ever work the way we want (wide viewing angles, etc), since it's a matter of physics, not technology. Not to mention the cost is always going to be higher, but not necessarily out of reach.

You can trade things, like smaller screens with wide viewing angles in exchange for resolution and amount of feasible parallax ("3-D depth"), so someone can showcase a 55" glasses free 8k 3D TV and produce images that are actually like 640x480 per-eye and with limited depth of a few inches in-front and behind the screen and can be seen up to 45 in front of it, but that's not really (and will never be) the glasses-free 3-D TV we have all been expecting for ... 100 years?

To anyone waiting for a glasses-free 3D TV at home: just go out and get yourself a projector (due to the lack of 3D TV being manufactured, though I'm sure some model will get hacked in the future into active 3D). Movie theaters COULD be made 3D w/o glasses due to having controlled seating positions so you know roughly where the heads/eyes of the audience are in space, but theaters can't even be bothered to convert to laser illumination or better 3D/sound systems, so I wouldn't hold my breath either.

Last edited by globalimages; 09-18-2020 at 04:13 AM.
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Old 09-18-2020, 01:47 AM   #170
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Quote:
Originally Posted by Lee A Stewart View Post
Using a light-field camera, whatever you point the camera at gives you infinite focus. You are not hampered by existing light. Works in bright light and dim light.

It's not 3D as we think of it. It's real life as we see it. It's not contrived as you have to do using two cameras.
It isn't stereo 3D at all which is how we see. Just adjustable shallow depth of field after the shot. The best 3D images are going to be where you have everything in deep focus so the viewer can change where they want to see. Burned in depth of field prevents that. But it's also style too in some cases.
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Old 09-18-2020, 02:10 AM   #171
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Quote:
Originally Posted by tomtastic View Post
It isn't stereo 3D at all which is how we see. Just adjustable shallow depth of field after the shot. The best 3D images are going to be where you have everything in deep focus so the viewer can change where they want to see. Burned in depth of field prevents that. But it's also style too in some cases.
So what/how does a person who lost an eye see?

L-F cameras won't be used to make Hollywood Movies. They depend on the background/foreground single focus presentation. But it definitely could be used for nature documentaries, reality TV, etc.
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Old 09-18-2020, 02:41 AM   #172
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So what/how does a person who lost an eye see?

L-F cameras won't be used to make Hollywood Movies. They depend on the background/foreground single focus presentation. But it definitely could be used for nature documentaries, reality TV, etc.
They see with one eye, unless that's a trick question.

It's been used for a long time to have focus pre-set, but true 3D films shouldn't use that method. It isn't needed for stereo depth. I read a lot of complaints on 3D movies why half the image is out of focus and that's because it's been the style to set the focus of what the DP wants the viewer to see. That's part of 2D filming and really shouldn't exist with stereo filming. (It can and does obviously for styling reasons and to call attention or away from something. And most Hollywood 3D films aren't true 3D films in that they're made for 2D then adjusted for 3D afterward.)

But a true 3D stereo film should not pre-set focus on foreground or background subjects and let our eyes make that determination ourselves. This allows the best 3D image and depth. Your eyes will focus on the foreground and blur out the background, then you can focus on the background and the foreground is blurred out. When it's pre-set, you don't have that option.
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Old 09-18-2020, 03:37 AM   #173
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They see with one eye, unless that's a trick question.

But a true 3D stereo film should not pre-set focus on foreground or background subjects and let our eyes make that determination ourselves. This allows the best 3D image and depth. Your eyes will focus on the foreground and blur out the background, then you can focus on the background and the foreground is blurred out. When it's pre-set, you don't have that option.
In a lightfield display, with a film shot with a corresponding lightfield "camera", this is what would happen. You would see a 3D image and you could decide (with your eyes, at any given moment) what is in focus within that image (background, foreground, etc) and if there is too much distance, the part you are not focusing on would appear blurred, but you are free to focus in a different place and that part would "automatically" appear in focus, whichever part you want. Different spectators would be focusing in different parts of the image no problem.

This is NOT the way it works in conventional stereoscopic 3D cinemas. The WHOLE image is focused AT THE SCREEN, and like you said, the focus of the whole content of the image is baked-in and can not be changed.

In the case you mention that the whole scene appears in focus in a regular 3-D movie ('cos it has been shot with a very large depth of field, i.e.), when you "focus" in an object in the foreground the background DOES NOT go out of focus like it does in reality because the truth is, well, there is ONLY one focus point and it's the theater screen (or the 3D TV screen). Your eyes are ALWAYS focused on the screen and anything that appears focused on the screen you will ALWAYS see in focus and if you "blur" the screen by focusing your eyes say a few cm close to your face (like i.e. looking at your finger) then the WHOLE 3-D movie will be out of focus 'cos, well, you are not focusing on the TV screen at all, where the WHOLE image resides ...

This is one of the aspects where conventional stereoscopic cinema/TV/stereoscopic-VR differs from real life (and real-life systems like holography/lightfields) and is one of its drawbacks and cause of eye strain for the audience. Your eyes are ALWAYS focused at the screen plane/distance, but your eyes CONVERGE at points in the space that are in-front or behind the screen. This is called the "vergence/accomodation conflict" and it's one of the aspects of classical stereo imaging that has been widely studied.

https://xinreality.com/wiki/Vergence...ation_Conflict


Last edited by globalimages; 09-18-2020 at 04:03 AM.
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Old 09-18-2020, 04:25 AM   #174
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Yes, I played around with Lytro images before about 5 or 6 years ago. It's an interesting effect but it doesn't give any depth feeling to an image, only changing the focus points. And the images are too low resolution to work with, like 2mp. It's no wonder it didn't go over well. A higher resolution image is simply far more useful than being able to change the focus points later, at least for most in photography.

When you focus on the screen, you can't focus on the entire image at once (unless you're sitting real far away), you can focus your eyes on one part like the foreground and the rest is blurred out by your natural vision. —By blurred out I don't mean like out of focus like shallow DOF, I just mean you don't get perfect clarity on all of the image, just the part you're focused on. You're eyes naturally create the shallow DOF.

That's why I say, deep focus is really the way to go with stereo 3D and pre-setting the focus is not needed with native 3D. Aside from style, and whatever else a director wants you to see.

Most 3D films though now because 2D is the primary audience, they still follow 2D rules. 3D you let the viewer decide what part of the image to focus on and the natural vision is used to blur out the rest.

Yes, convergence is locked in at filming or adjusting in post, a limitation of what's possible but you can still focus the foreground and background independently with deep focus as there's nothing to stop you like when focus is pre set. Ideally, in natural vision the convergence point would change as the eyes focus on a subject closer and further away (and that does happen if a particular scene is being zoomed but even then one can still focus at other points than what the convergence point locks in as it's moving). Overall, it's not a huge limitation because in real life the screen would be all around us and it's not. Stereo 3D is after all, an illusion. It's a flat square or rectangular box sitting so many feet away from us. So that's another limitation until holodecks get here. Or maybe this Looking Glass thing. The 8K version looks cool but I don't see it working as something we could view our Blu ray 3D catalog on. Again, stereo 3D to 45v conversion, probably not great. You need real 45v pixel depth mapping for it to work right. So each movie would require real proprietary conversion for the screen. That's why they're only showing images of faces and such. Not much movement going on. Try it with movement and we'll see.

Now, to add. You can get stereo from different focal points. There was a single camera macro rig that a guy built to film Micro Monsters BBC. And it's basically a single lens camera and gets split by a prism into two recording modules. But in this case the 3D effect is created (I believe) from the different focal points and physically different parts of the lens, so not created from the blurring so much as it's a different part of the lens. I didn't notice that with Lytro. Looked more like out of focus in the back and then when it's changed, out of focus in front. And the degree of 3D with that effect is minimal at best, not a replacement for interaxial space, which is why it's only been used for macro that I know of.

Last edited by tomtastic; 09-18-2020 at 04:49 AM.
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Old 09-20-2020, 11:24 AM   #176
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But in this case the 3D effect is created (I believe) from the different focal points and physically different parts of the lens, so not created from the blurring so much as it's a different part of the lens. I didn't notice that with Lytro. Looked more like out of focus in the back and then when it's changed, out of focus in front. And the degree of 3D with that effect is minimal at best, not a replacement for interaxial space, which is why it's only been used for macro that I know of.


Watch the video above about the Lytro CINEMA (not their PHOTOGRAPHY) camera at about the 8:00 minute mark. You can see with a (appropriate) lightfield camera like that you can, of course, get TRUE (as in 100% what we are talking about) stereoscopic image of ANY interaxial you want (within the constrain of the width of the sensor) which in this case is up to some 10cm (that camera has a up-to 104mm interaxial equivalence), so you can get the FULL range of interaxial used typically in current 3D stereocopic cinema.

So this camera can produce a TRUE stereocopic image of NOT ONLY the usual 6.5cm interaxial, but ANYTHING IN BETWEEN AND ABOVE (macro and hyper stereo, i.e.) and does it "at the same time", thus you get the multiview-equivalent of basically infinite-view (you see objects in different places in space with each eye as you move horizontally, like in real life, up to the width of the sensor/sensor-array) AND as a "plus" you also get infinite-focus (you see ANYTHING you want in focus, far or near by just refocusing your eyes, like in real life).

The problem I think is that you are talking about the Lytro PHOTOGRAPHY CAMERA and then viewing it in a 2D monitor or even a conventional 3D TV, which of course as you say is pretty useless for the glasses-free 3D display of movies that we are discussing here, and at best could be used to produce a small-interaxial multi-scopic image, like you mention, while we are talking about the Lytro CINEMA CAMERA and then viewed in a LIGHTFIELD DISPLAY, not a regular 2D/3D monitor like they are showing in the youtube video explanation, i.e.

A lightfield camera with all the (huge amount of) information being sent to a matching lightfield display is, intrinsically, true-3D and true-focus, as in real life, within the constrains of the size and resolution of the "sensor/sensor array" of the camera and the size and resolution of the LIGHTFIELD display.



Last edited by globalimages; 09-20-2020 at 08:46 PM.
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