Optimizing 3D for TV's with passive glasses

[hesido]

Aside from a resolution disadvantage, TV sets with passive glasses (without active shutter) provide a very compelling 3D experience, flickerless, slightly brighter, with very little cross talk and their sales seem to have caught up with active shutter 3d sets ( http://www.3d-display-info.com/tags/market-reports )

Since passive 3d sets only 540 display horizontal lines per eye, games would only require a 540p resolution for both views, possibly a Top&Bottom 1080p picture would do fine. What I wonder is, do console games make use of this reduced resolution? Currently they surely don't ask any questions or have any setting with regards to this. Passive sets provide support for true 1080p 3D while displaying only half resolution of that, and I'm skeptical that they can relay information to the console through HDMI that a Top&bottom half-res 3d format should actually be preferred.

Since most games will be targeting 1080p next gen, they should be able to provide a 540p per eye 3d experience with little impact on framerate (I know two distinct viewpoints require more than that, but much of the information will be reused for both views), and it's not really optimal to go for 720p per eye as most of those pixels won't contribute to what can actually be viewed anyway.

I'm hoping for devs to account for this and give us options, or better yet do this transparent to user if possible at all, I'd like to hear if games have already been using / will be using Top&bottom half resolution modes for 3D next gen...

 

[Arwin]

I don't know if there's a real advantage to be found, rendering wise (though probably a little) and I don't even know that these TVs can handle a 540p per eye input.

I think advantages partly happen sort of automatically, by giving you double the framerate per eye, but agree that dedicated optimisations may be able to offer more.

Having a passive 3D 27" TV, a very cheap one at that (277 euro, and that was like 6 months ago) which came with five pairs of glasses to boot, I can definitely attest to how great that can look (as I've done several times here on the forums ).

 

[Lalaland]

I loathe passive 3D, why on earth would we reinvent interlacing? It's the primary reason I hunt down 2D screenings of new releases in my local cinemas. Is there even a specific HDMI format for different types of 3D, I thought it was just side by side frames with the panel performing any necessary fiddling.

 

[TheWretched]

I have an older LG passive 3D monitor for PC... the included software (Tridef) doesn't even let me render "natively" (1920x540) per eye, interlaced. Might be possible (odd resolutions on PC aren't uncommon), just line doubling in the end might be "too much" to retrofit it via external hooks.

PS3 games don't care for how the display works. All games I tried use frame packing 3D in 720P, though I assume some allow SBS or TB, or AFR.

Sadly, my monitor has the worst viewing angles with the glasses, so I don't use it much for 3D anyways (still a good 2D monitor, at least). The newer LG tvs work much better in that regard.

 

[Arwin]

I loathe passive 3D, why on earth would we reinvent interlacing? It's the primary reason I hunt down 2D screenings of new releases in my local cinemas. Is there even a specific HDMI format for different types of 3D, I thought it was just side by side frames with the panel performing any necessary fiddling.

In theory I have always agreed, until I saw the difference in practice, where you need at least 120hz for active shutter glasses to have a somewhat fluent experience and pixels can't quite keep up (unless perhaps OLED), passive, while less sharp, just looks great and is much more comfortable to watch, not to mention all the advantages of the cheap glasses.

Ideally of course there would be a solution that has the best of both worlds. Still waiting for that one though. Meanwhile, this looks great.

 

[hesido]

.... I don't even know that these TVs can handle a 540p per eye input.

Well, all they'd have to do is provide a Top&Bottom 1080p rendering, 540 lines per each eye solved right there.

I loathe passive 3D, why on earth would we reinvent interlacing?

It's not interlacing as in you display a different line every 60th of a second, the lines are always displayed, and there's a black line for every visible line for each eye. Active shutters are, well, flickering and there's quite a lot of cross talk in all but 240hz capable sets. And passive glasses are dirt cheap, realD glasses you get from theaters work.

But anyway, the question is, games could be using this lower resolution to their advantage, I'm surprised they don't seem to. Half of the sets are passive. Maybe we are unlucky Sony themselves don't produce passive sets.

 

[Strange]

Passive glasses don't work by interlacing, they work by the TV emitting two types polarized light (just offset the two sets by 90 degrees) and the glasses themselves simply block off the respective polarized light.

To see if your passive glasses work exactly this way, next time tilt your head 45 degrees to one side and see if you see both images with both eyes. Furthermore, if you tilt your head 90 degrees, see if you see the "wrong image" for both eyes. If you do then the system is working as intended.

Last time I was in a IMAX theater with passive 3D glasses they work exactly this way.

It wouldn't be hard for the 3D sets to simply double up on the resolution to deliver full resolutions to both eyes I think. We ARE looking at 4K resolution TVs hitting the markets, and this technology is much easier to adapt than active shutter ones, and hold much more potential. Especially if IMAX theaters have apparently decided that these are the way to go.

Think one day that everybody would be able to carry around a clip-on with these polar membranes and we'd be able to see amazing 3D effects on the streets.

 

[Lalaland]

It's not interlacing as in you display a different line every 60th of a second, the lines are always displayed, and there's a black line for every visible line for each eye...

It's practical effect is to interlace the image, any fast moving object or camera pan shows this effect off at it's worst with the classic 'comb effect' on the edges. If every other line is visible to only one eye any pan will show the effect the loss of resolution, this is the main reason I dislike 'RealD' (passive tech branding in my local cinema). Depending on the content it's more or less visible but I find it quite maddening personally.

I'm not arguing in favor of any one 3D tech as a wearer of eyeglasses they're both quite awkward. Overall I'm quite sceptical of the whole endeavor and am only in favor of it because it gets me 120hz for playing back film content at a nice and smooth 24fps.

 

[Strange]

It's practical effect is to interlace the image, any fast moving object or camera pan shows this effect off at it's worst with the classic 'comb effect' on the edges. If every other line is visible to only one eye any pan will show the effect the loss of resolution, this is the main reason I dislike 'RealD' (passive tech branding in my local cinema). Depending on the content it's more or less visible but I find it quite maddening personally.

I'm not arguing in favor of any one 3D tech as a wearer of eyeglasses they're both quite awkward. Overall I'm quite sceptical of the whole endeavor and am only in favor of it because it gets me 120hz for playing back film content at a nice and smooth 24fps.

I doubt this will remain a problem when you up the resolution back up to the usual 1080p per eye and you maintain a good angular resolution to the eyes.

Interlacing gives you the comb effect at the edges when moving because the "edge" is only half-refreshed.
You refresh half of the edges one frame, and the other half on the next, giving you the "comb".
However, this shouldn't be a problem with 3D passive because the entire image is being refreshed every frame.

If you see the comb on the passive 3d TV sets, then you'll also see them on a 3DS, which obviously isn't the case for anyone with an experience with the 3DS.
the 3DS method and passive TV use different techniques to accomplish the same thing. The 3DS selects your eyes by autostereoscopy, and the passive TV glasses use polarized light.

You're getting two 1920*540p images refreshed every frame, which is very different from 1920*1080i.

 

[Davros]

that will require 2160p though (4k) wont it

 

[Strange]

that will require 2160p though (4k) wont it

not exactly. You only have to double either the vertical or horizontal.

so it would either be 1920*2160 or 2840*1080.

basically half the resolution of 4k screens.

 

[Lalaland]

...It gives you the comb effect at the edges when moving because the "edge" is only half-refreshed.
You refresh half of the edges one frame, and the other half on the next, giving you the "comb".
However, this shouldn't be a problem with 3D passive because the entire image is being refreshed every frame.....

You're getting two 1920*540p images refreshed every frame, which is very different from 1920*1080i.

No in practical terms it's the same thing, for passive 3D to eliminate the interlaced comb effect it requires...

....You only have to double either the vertical or horizontal. so it would either be 1920*2160 or 2840*1080. basically half the resolution of 4k screens

Implicitly every passive set on the market right now is only offering 1080i (aka 2 x 540p) If we were getting the panels you describe there wouldn't be any interlacing but we're getting half res. per eye and for me that's a deal breaker due to the interlacing I perceive on fast moving objects.

 

[Strange]

No in practical terms it's the same thing, for passive 3D to eliminate the interlaced comb effect it requires...



Implicitly every passive set on the market right now is only offering 1080i (aka 2 x 540p) If we were getting the panels you describe there wouldn't be any interlacing but we're getting half res. per eye and for me that's a deal breaker due to the interlacing I perceive on fast moving objects.

That doesn't make any sense.

in 1080i you're only refreshing 540lines per 1/60 seconds

in 2*540p you're actually refreshing all 1080 lines every 1/60 seconds.

Getting half res doesn't translate to interlacing.


To illustrate the example, here's a screen

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

To see the "comb effect" you would have to see the D pixel unrefreshed and the B pixel refreshed. This occurs in 1080i, when you move the B pixel, say, for example 2 pixels to the right within 1/60 seconds, you will get this:

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

And here's how the comb occurs.


However, in passive 3D, BOTH D and B pixels are refreshed every 1/60 second, and thus the "comb" effect will not and should not occur, since your Left eye sees



CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC

CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC

CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC

CCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDCCC

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

and your Right Eye Sees

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC

CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC

CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC

CCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCC

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

At the same time. after 1/60 seconds, BOTH D and B pixels get moved by the same 2 pixels as above to the right and you'll simply see the following on both eyes

Left
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC

CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC

CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC

CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC


Right

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC

CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC

CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC

CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC


Assuming they're playing the same image, you'd see

CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDC
CCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC

Thus there shouldn't be a comb.

In 3D these images shouldn't be the same I acknowledge that but that isn't a reason for the combing effect either.


Note: A didn't work, I changed to using B and D instead

 

[hesido]

@lalaland: Like Strange says, indeed, I don't see why you would see combing (I see none, and I'm usually good with visual assessment ). There's no temporal discrepancy in passive 3D, both images for eyes are displayed at the same time..

Maybe there's some other problem you are noticing due to the setup of your movie theater.

Anyhow, I continue to be surprised at how devs aren't making use of reduced resolution.

 

[Jedi2016]

I doubt anyone will make any special concessions just for passive 3D sets. They'll just continue doing it the way they do it now.. simply render the 3D frame-packed (like a Blu-ray disc), and send that signal to the TV, and the TV just... does its thing, dependent on what type of display it is.

And yes.. there's no combing unless you have the glasses off. The only artifacts I see at all is some slight aliasing on some straight edges, depending on the contrast and angle. And bear in mind that, as a VFX guy, I'm better "trained" to spot discrepancies in the image like that. Most people I know wouldn't even notice them.

I use passive exclusively, for what it's worth. On both my PC monitor and my TV downstairs. Not only are the glasses between them interchangeable, I can take them to the theater, and they're a hell of a lot more comfortable than the **** ones they hand out at the box office.

 

[TheWretched]

Yeah. I usually wear glasses, because of my short sightedness, and my LG monitor shipped with a clip on... much better than what you get at the theater.

 

[orangpelupa]

passive 3D tv are awesome. I dont see the flicker or the crosstalk.
the low resolution also good for pc gaming in 3D*

Of course you also can use half resolution on Active 3D but it looks blurrier, its flicker, and it have worst crosstalk.

*only matter if you have slow GPU like me.

as for console, they already lower the resolution of Active 3D. I dont see the difference in framerate between running 3D game on active 3d or in side by side mode.

But for ps4 and xbone games, if they limit their game to 720p or lower, i hope they can display 3D game without compromise. (without harsher LoD, still have the same anti aliasing, etc).

 

[Davros]

as for console, they already lower the resolution of Active 3D.

Didnt know any console did active 3d, that would require 120hz

 

[TheWretched]

Not really. Most of Sonys games use frame packing, which essentially sends 2 720P framebuffers at 60Hz to the TV. Some use SBS or TB, halving the sent resolution (which is probably less, even before sending, anyhow).

 

[Jedi2016]

I will say that's one advantage of passive gaming on PC.. the 3D is converted in the graphics card and sent already interleaved for 3D. In essence, just one 1080p stream rather than frame-packed, so it can support full 60fps in 3D as long as the game itself can push it. Bearing in mind that's done AFTER the game itself renders the full two frames, so there's still a significant performance hit on gameplay, just not on the video stream.