Top-Bottom 3D vs. Side-by-Side on Passive Display - Page 3

Okay. Thanks. So passive FPR is interleaved, 1920x540 per eye, refreshed interleaved and progressively 120 times per second?

And yeah, I've seen the recommended 3D viewing distance before. Unfortunately, sitting 4.25 feet from my TV isn't very desirable. That's too close to the screen for my liking, and it doesn't really work with the furniture arrangement in my apt or for video quality reasons. I'll just have to buy a big house and a bigger 3D display sometime in the future.

Thanks very much for that 3D viewing distance information calculations.
I noticed myself with my new 50" Panasonic Plasma 3D HDTV, the need to move closer watching full 3D bluray movies compared to 2D video.
My normal viewing distance with the 50" screen is about 7-8 feet, but thru trial&error I found for watching full active 3D titles I would move the couch up to 5feet - and that ends up very close to your 1.4x display-width calculation.

IMHO if the 540 even lines for the right eye replace the 540 odd lines for the right eye after 1/120 of a second and the same process occurs for 540 even and 540 odd lines for the left eye. Then each eye sees it's 1080 lines each second. The eye/brain does not realize that the the left eye lines replaced the right eye data and therefore integrates the two images resulting 1080p per eye every second. This would be exactly the same process that a 480i CRT display uses when it first displays the first 240 lines and then displays the second 240 lines after the first 240 lines have fadded from the screen.

So you are claiming that watching native 1080i on one of the old 3 CRT HD RPTVs would be the same as watching native 1080P on a flat panel 1080P HDTV?
Edited by Lee Stewart - 7/14/12 at 2:24pm

The problem I see with this logic is for example the left eye, 540 lines are displayed on lines 1,3,5........Etc. Lines 2,4,6... Etc. are seen as black. The material meant for lines 2,4,6..... are then shown 1/120 Sec. later but that material is shown on lines 1,3,5,.... Etc. Lines 2,4,6.... Etc. remain black. This is not like your 480i CRT example where the lines are displayed in their proper place and there are no lines permanently black. The technique of displaying the missing lines on the wrong lines is LG's way of claiming 1080 resolution. I've read some places that it causes minor artifacts where the image is slightly offset at the edges of objects or the ends of lines..

Huh?

With passive 3D, there are no "black lines"

The left eye is seeing 1,3,5 . . . etc while the right eye is seeing 2,4,6 . . . etc . . . at the same time.

In 1/120 of a second, the TV is displaying 540 fields per eye at the same time.

In 1/60 of a second, you see 2 complete L & R frames (each 1920x1080) at the same time.

And yes - because the display is using Interlace to create the images, you can get artifacts associated with interlacing and deinterlacing.
Edited by Lee Stewart - 7/14/12 at 6:18pm

By black lines I mean lines that can't be seen because of the polarized film applied to the screen. The left eye lens of the glasses is polarized so that the lines intended for the right appear black to the left eye. But you can believe what you want. look very close to the screen. If you can't see black lines (sometimes called a screen door effect) you are not looking at passive 3d through passive 3d glasses.

When watching 3D, don't you have both eyes open at the same time? So this will negate whatever it is you are describing.

Being able to see the scan lines when you move close to a passive 3DTV (wearing passive 3D glasses) is due to the interlacing of the L & R images on the display, at the same time, each made up of 540 fields.

I have a passive display, so I'm pretty sure I'm looking at passive 3D through passive 3D glasses. And I don't see a screen door effect when watching 3D content. I also don't watch my screen from four inches away, either.

What specifically are you looking at when you see the "screen door effect"? It's visible at times when viewing 2D content, like this web page right now, with it's pure white background. But I tend to not wear the 3D glasses when I'm not, you know.. watching 3D content. The lines effectively disappear when the 3D effect is turned on.

I am talking about both eyes open. The left eye sees 540 black lines. The right eyes sees 540 black lines. Both eyes together see 540 black lines.

In a study by Joe Kane of Joe Kane Productions and Scott Wilkinson of Hometheater.com at this link
http://www.hometheater.com/content/closer-look-active-vs-passive-3d-flat-panels

They state the following

"Makers of such sets claim that, while each eye sees only 540 lines, the brain combines the two images into one, resulting in a total of 1080 lines. However, Kane disputes this, saying that the two images must be kept completely isolated from each other or we would see no 3D effect at all, and if each eye sees 540 lines, that's the total effective resolution"


If you look at an active display at 4" you see no lines. At a passive you see every second line of pixels as a black horizontal line. Of course if you reduce the sharpness enough you can reduce this effect, but then you have a softer picture. By the way, I'm not taking about the pixel grid. look at the picture in the linked article showing a close up image through glasses.

You really think you're going to change my mind? I'm sure as hell not going to change yours, so I'm done discussing it. Believe what you want. I'll stick with what I can see, thanks.

I was thinking the same thing and almost decided to post your message almost word for word. this is a very old argument and I don't think anyone has changed. It's mostly based on what people own and spent thousands for.

Take Care
Over and Out

It seems that there are some undocumented differences between 3D passive televisions.
For example:
My Vizio 32 inch displays 3d just fine in 2D mode when the input is line interleaved.
So does my LG 23" monitor.
My 65LM6200 however does not display 3D in 2D mode under the same circumstances.
I do not know why this is but perhaps it is for the same reason that I can not see any black lines with the glasses on.

These people who think passive now is 1080 are going to be surprised when the 4k passive sets are out that will be true 1080 passive. I just can't wait so people can compare the 2 then they will understand.

My LG 65LM6200 does not display 3D when receiving a 1920 by 1080 60P line interleaved 3D image when it's in 2D mode!!!
What it displays looks the same with and without the 3D glasses on.
Both my other passive displays show in 3D while receiving the same input.

Anyone care to offer a "plausible" explanation for this?

Frank, is your set adjusted for 1:1 pixel mapping? Many sets default to overscanning.
The vertical "pixel fill factor" per eye of a 3840x2160 passive 3D screen will be less than ideal, as each eye sees only every second horizontal line. Those people (including myself) who currently see prominent horizontal black lines when viewing a 1920x1080 passive 3D set operating in 3D, may still detect a lack of vertical smoothness at very close viewing distances. But yes I think there should be a marked improvement.

I think that if active sets are to compete they will need to do better than the current 120Hz actual alternation rate (which some, including me, find "flickery"), with low ghosting, and high brightness.

Yes, it is.
Nice try though.
Any other ideas?

Well if it's already set for pixel maping all I can think of is motion interpolation getting in the way.

I disabled the smooth motion and it had no effect on the lack of 3D.
It's really bizarre what it's doing and doesn't make a lick of sense to me.
There must be some algorithm in play that's causing it.

Apparently the algorithm is sensing that the incoming signal is interleaved and simply not handing it correctly unless the 3D mode of the TV is forced on.

I don't get how that's even possible.. the retarder layer is physically built into the LCD panel.. if it's fed an interleaved source, it HAS to display it that way, which, by default, would work.

My Asus monitor has yet to have it's "active" 3D mode even turned on, and I view 3D content all the time. The software just feeds an interleaved signal to the monitor, and thus it displays in 3D. It's how I watch YouTube videos, even.

I think your last statement is correct.. the TV is somehow able to detect the incoming signal is 3D and, since the TV is set to 2D mode, it removes one of the images and interpolates the missing information from the remaining image. Really, it should be treating the image "as-is" like mine does.

Yes it seems the set may be sensing the interleaving and may be extracting only a 2D version unless specifically instructed otherwise. One way to check things would be to send it some 2D material with an inset 3D interleaved photo (which it presumably would NOT sense). If it pixel maps correctly, the alternate lines in the photo would appear on alternate lines on the display. Bit of a nuisance though that it will not display in 3D by default.
Edited by MLXXX - 7/15/12 at 9:45pm

Of course it will be better, it will be true 1080 passive. I just want to know what all the passive people are going call it if they call them 1080 now. I don't think active has a problem competing and I think will always have a market especially in Dlp devices like projectors and Dlp tv's which I feel produces the best 3d imo. The problem with passive is it's limited to lcd,led displays which are the worst for 2d and 3d compared to plasma and Dlp.

Lewis, I am looking a few years into the future.

For displaying of the 48fps 3D movies currently in production, at home using a new home plasma TV set standard, I would not underestimate the challenges of raising the alternation rate of domestic shutter glasses for plasma displays. There could be an increase required from the usual 120Hz, to the 144Hz currently used in the cinema for 3D 24fps film (RealD), and on up to the more desirable 288Hz. By 288Hz I do not mean timing fineness in the duty cycle relating to blanking. I mean the following patterns of actual Left and Right alternations:

• Each 24fps frame would be shown as: L₁R₁ L₂R₂ L₃R₃ L₄R₄ L₅R₅ L₆R₆, i.e. 6 flashes of Left interspersed with 6 flashes of Right
• Each 48fps frame would be shown as: L₁R₁ L₂R₂ L₃R₃, i.e. 3 flashes of Left interspersed with 3 flashes of Right

To execute these patterns successfully with low ghosting might require precision in blanking times corresponding to 1153Hz. (In detail: using a duty cycle of 75% "on" time and 25% "blanking" time.)

The above is well beyond the capacity of current domestic plasma screens while maintaining fineness in levels of brightness and colour. However with passive LCD displays it would be quite feasible to display 48fps 3D material using current domestic screen technology with minor alterations to timings.

If manufacturers could make plasma 3D sets work successfully at a 144Hz true alternation rate that would be a good start, but it is very challenging without losing brightness and without increased stereoscopic cross-talk. Unfortunately, plasma screen technology is ill-suited to high frame rate 3D.

P.S. Projectors for passive glasses can use a single light engine with an alternating polarizer; or two light engines with a fixed polarizer for Left and complementary fixed polarizer for Right.

EDIT: On the main topic of this thread, logic suggests to me half top-bottom rather than half side-by side; given that passive displays can take full advantage of horizontal detail in the source, but are already compromised in what can be displayed accurately in the vertical direction. However it should not be difficult to create two test clips and run them sequentially with software or a display that automatically switches between half top-bottom and half side-by-side.
Edited by MLXXX - 7/16/12 at 6:09pm

I expect plasma 3d technology to change as has all others it might take some time but it will come. I think led,lcd tv's just don't cut it for 3d the technology it's just too slow. I have 6 lcd,led displays in my house and they are ok, but the image compared to a plasma or dlp is very poor . The projector setups you mentioned even some of the dual setups requires an expensive silver screen and of course the dual setups you have to have dual projectors which is double the cost. Active 3d dlp will own the 3d projector market for a long time especially since now active glasses are cheaper than ever, some around $20. I would also have to say on the current topic that top and bottom is better than side by side on a passive display. I think a test was done on this somewhere I will try to find it as the tab came out on top.
Edited by lewis3845 - 7/16/12 at 10:22am

Frank,
Do you still have your Mits RP DLP 3D TV? If yes how does the passive LG LM6200 compare with it?
Do you have any comments on my thoughts in my post #63?

They don't compare at all. My entire family prefers the LG by a very wide margin.
The only thing the Mits has over the LG is the size. I still have it but it's moving to my office building soon along with two Samsung UN40C7000s and a Samsung Pn63C7000. It's not the same thing as an interlaced CRT. The odd and even lines of a interlaced CRT are actually displayed at least partially at the same time because of the phosphor decay time.
As far as this odd even 540 alternating line issue goes, I have been unable to fine a way to test it so far. I'm still researching it.

Frank thank your for the update.
How do the active Samsungs compare with the passive LG?
I agree the CRT and the passive are not really the same. I should have realized that the newer CRTs have longer lasting phospers then the older CRTs had, but the concept of the two different images being integrated by the human mind and the concept I still think might be valid for those passive models that do not show black lines like your LG.

The very first comparison I did was watching my 3D parrot drone video. 3D Parrot Drone video
It was impossible to watch on the Samsung UN40C7000 because of the severe ghosting. It is a pleasure to watch on the 65LM6200 (no ghosting) Case closed! Bye Bye Samsungs! I am able to watch extremely high quality 3D on my passive TVs by feeding them with 1080P60 top and bottom from a combiner which combines the HDMI outputs of dual Canon HF-G10 camcorders. The image quality is as good as anything and beats the pants off 3D Blu-Ray IMO.

Let's just say, I'm not longing for a 4K passive at the moment.

I got a simple question, which I'm having difficulty finding information on.

I have an active 3D TV.
http://www.samsung.com/ca/consumer/tv-video/tv/led/UN46D6420UFXZC

So therefore I need to use active glasses.

Am I able to watch SBS 3D on an active TV with active glasses?

If not, what format do I need to watch on an active TV?

Thanks

You can watch any of the 3D formats (SbS, Top/Bottom or Frame Packed) on your active 3DTV and glasses.