Official Omega 3D passive projection system thread - Page 26 - AVS Forum | Home Theater Discussions And Reviews
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post #751 of 770 Old 12-12-2016, 11:54 PM
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Yes, the visual crosstalk pattern is in this thread : The Ultimate 3D projection system: A Practical Discussion Thread

Indeed, the hotspot is visually nowhere to be found, but this is thanks to the screen curvature. (hiding hotspots from high gain screens is the whole point of curving screens)
However, if you look at the photo, you can clearly see a striking brightness difference between the middle of the picture and the top&bottom edges.

I received my new screen from XtremScreen, I'll set it up and do a full report as soon as I can.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #752 of 770 Old 12-13-2016, 06:17 AM
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"However, if you look at the photo, you can clearly see a striking brightness difference between the middle of the picture and the top&bottom edges."

The camera adds hotspot there is not even half of the amount to be seen with naked eye.
The grainines is my only conplaint.
Im eagerly waitin for your report on the
Daylight 1.1 special 3D edition.. is what they call it ?
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post #753 of 770 Old 12-13-2016, 09:09 AM
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The Daylight 1.1 "special edition for polarised 3D" (my name, not theirs) was actually a research material from when they developed the Daylight 1.1 référence screen material.
It is not a full production material and they only have a limited quantity of it.
Unfortunately, the research material could not be transformed in a shippable screen. The material is too fragile and cannot handle rolling for transport.
It has to be attached to a full solid frame (a plank) in order not to fall apart, the solid frame works but is such a nightmare for transport when doing a full sized screen that they abandoned the idea. (and I agree 100%)
XtremScreen cannot afford to put a completely new formula into production specifically for the 3D poalrized market (too much of a niche market). They need to be able to sell the material for both 2D and 3D and not compromise the 2D aspect since this market represent 99.9% of their sales.

The new material I have is Daylight 2.0 (with 2.0 gain). I've tested a sample for polarized light (it is on par with my previous Harkness 240 silverscreen) and I have seen the screen in 2D at their showroom and it looked like it was in the sweet spot between gain, hotspot and sparklies/shimmer.
I just finished setting up the screen, I'll try it this evening.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #754 of 770 Old 12-17-2016, 03:12 AM
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Quote:
Originally Posted by BlackShark View Post
The Daylight 1.1 "special edition for polarised 3D" (my name, not theirs) was actually a research material from when they developed the Daylight 1.1 référence screen material.
It is not a full production material and they only have a limited quantity of it.
Unfortunately, the research material could not be transformed in a shippable screen. The material is too fragile and cannot handle rolling for transport.
It has to be attached to a full solid frame (a plank) in order not to fall apart, the solid frame works but is such a nightmare for transport when doing a full sized screen that they abandoned the idea. (and I agree 100%)
XtremScreen cannot afford to put a completely new formula into production specifically for the 3D poalrized market (too much of a niche market). They need to be able to sell the material for both 2D and 3D and not compromise the 2D aspect since this market represent 99.9% of their sales.

The new material I have is Daylight 2.0 (with 2.0 gain). I've tested a sample for polarized light (it is on par with my previous Harkness 240 silverscreen) and I have seen the screen in 2D at their showroom and it looked like it was in the sweet spot between gain, hotspot and sparklies/shimmer.
I just finished setting up the screen, I'll try it this evening.
Any comment yet on the new screen ?
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post #755 of 770 Old 12-17-2016, 09:09 AM
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I'm still planning out a modest budget Omega 3d setup. I have to ask, just how valuable is lens shift in selecting a projector. Adding that restriction can add 50% to what you end up spending in a projector. Is it worth the investment? I can see how it would be useful in principal but what about the practical? I've done 3d before and it seems that the human visual system is very good at converging images and doesn't seem to care much if the images are half a degree out of convergence. Its the kind of thing we are used to dealing with when keeping our eyeballs aligned in the same direction. Has anyone had some real experiences comparing lens shifting to not? If I had a lens shifting pair of projectors, I could center both internally and align as well as possible and compare the results with using the lens shifting. What about horizontal mounting with enough horizontal lens shifting? Any success stories out there? It would make for more convenient access to the projectors and a more natural look on the ceiling. What experiences have people had with this? Thanks.

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post #756 of 770 Old 12-17-2016, 01:09 PM
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Quote:
Originally Posted by Vaan Janne View Post
Any comment yet on the new screen ?
I have not written a full review yet, but so far I love it.
The Xtrem Screen Daylight 2.0 has great picture quality, in my living room, at 1.5 throw ratio / 1.5 view ratio (projector on a tall shelf just behind the couch), invisible hotspot in the centre of my couch (best seat in the living room), the hotspot becomes visible from the side seats (outside of the frame footprint) but significantly less annoying than my previous silverscreen.

Polarisation retention is excellent (finally, I am getting transparency again), only scenes with extreme contrast show crosstalk (bright stuff on absolute black background).
I get the exact same high extinction as on the small sample I tested. On my visual crosstalk test pattern, pure white bleeds at the level of 10~15% grey on the Daylight 2.0 : the same as my Harkness Spectral (which had a 130:1 peak extinction ratio).
It's a dramatic improvement over the Daylight 1.1 (25% grey) the but not as good as the optimal but unshippable prototype (which was <5% grey)
---Important note : crosstalk values are visual measurement (not precise) and not an absolute screen characteristic measurement : they can only be used to compare screens on the same projector system since the results vary based on the projector type and filters used----

The 2.0 gain boosts the brightness of the picture significantly (up from 1.1 gain), the picture really pops again, but consequently, the poor black level of my projector is also brought forward with it, and the ambient light resistance is also lower. (can't get something for nothing)

Shimmer/sparkle wise, I have to admit I am spoiled by the Daylight 1.1 Référence : the 1.1 Référence screen material has extremely low shimmer/sparkle, many people I've talked to claim it's the lowest on any technical (non matte) screen.
So on the Daylight 2.0, I do see some of it on the brightest content (large very bright non-textured surfaces) but it's well contained. It's not shocking like on my previous silverscreen.
On more realistic content the shimmer/sparkle is low enough to become transparent. I know it's there but I don't notice it.

In short : I love this screen, It's the kind of screen I wanted when I started searching for a better screen 2 years ago. (less sparkle and less hotspot than my previous silverscreen, without compromising on the crosstalk). It was an expensive endeavour though, but I know half of the cost was the professionally made frame (instead of my DIY piece of crap I used before) and it looks really great in the living room.
No pictures yet. I'll take some and publish them, along with text explanations in the other more appropriate thread (Ultimate 3D projection thread).

Quote:
Originally Posted by foxpup View Post
I'm still planning out a modest budget Omega 3d setup. I have to ask, just how valuable is lens shift in selecting a projector. Adding that restriction can add 50% to what you end up spending in a projector. Is it worth the investment? I can see how it would be useful in principal but what about the practical? I've done 3d before and it seems that the human visual system is very good at converging images and doesn't seem to care much if the images are half a degree out of convergence. Its the kind of thing we are used to dealing with when keeping our eyeballs aligned in the same direction. Has anyone had some real experiences comparing lens shifting to not? If I had a lens shifting pair of projectors, I could center both internally and align as well as possible and compare the results with using the lens shifting. What about horizontal mounting with enough horizontal lens shifting? Any success stories out there? It would make for more convenient access to the projectors and a more natural look on the ceiling. What experiences have people had with this? Thanks.
Trapeze has a very high influence on 3D and must be corrected for 3D to look good !

The most efficient correction is vertical trapeze correction (it's due to the geometry of 99.9% of projectors, they're built wider than tall, so you have less correction to do if you stack them vertically)
Also, most projectors only provide vertical trapeze correction, only a few provide both horizontal and vertical trapeze correction.

The most important issues with using trapeze correction are :
-image quality (trapeze require scaling, it's a minor annoyance on most content, only an issue if you're doing computer games with tiny text or if you want every single pixel on the matrix intact, like me)
-setup complexity (this is the biggest one for dual-pjs : position of the projectors in the room, tilt, zoom and the amount of correction of both projectors are all interdependent, change one single parameter and all the others change, you'll spend a lot more time setting your projectors up)

At the moment, I haven't seen any projector manufacturer providing a lens shift on a cheap entry level projector like Epson used to do a few years ago.
I am very glad I bought my projectors 5 years ago, just before the 3D boom because projector manufacturers had very few extra gadgets to differentiate themselves and had to use the hardware to differentiate themselves from the competition. I had the choice between 1000€, 1200€, 1500€ and 1800€ projectors within the same line, all equipped with the exact same ultra-wide lens shift system with progressively better picture quality as the price went up. I had a golden opportunity to fine tune the quality/price ratio.

Nowadays, lens shifts tend to be only added on the mid to high-range. Manufacturers use other features to differentiate between sub 1000€ projectors and the start of lens shifts (3D, image processing, networking, wireless hdmi, etc...)
But since the price is much higher, if you do choose a projector with lens shift, you'll be aiming for projectors with significantly higher base picture quality (the price isn't only about the gadgets and the lens shift, manufacturers must also improve picture quality to justify the ridiculously higher prices).

If you are on a budget, you probably don't have a choice and should do without.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


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post #757 of 770 Old 12-17-2016, 01:28 PM
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Quote:
Originally Posted by BlackShark View Post

Trapeze has a very high influence on 3D and must be corrected for 3D to look good !

The most efficient correction is vertical trapeze correction (it's due to the geometry of 99.9% of projectors, they're built wider than tall, so you have less correction to do if you stack them vertically)
Also, most projectors only provide vertical trapeze correction, only a few provide both horizontal and vertical trapeze correction.

The most important issues with using trapeze correction are :
-image quality (trapeze require scaling, it's a minor annoyance on most content, only an issue if you're doing computer games with tiny text or if you want every single pixel on the matrix intact, like me)
-setup complexity (this is the biggest one for dual-pjs : position of the projectors in the room, tilt, zoom and the amount of correction of both projectors are all interdependent, change one single parameter and all the others change, you'll spend a lot more time setting your projectors up)

At the moment, I haven't seen any projector manufacturer providing a lens shift on a cheap entry level projector like Epson used to do a few years ago.
I am very glad I bought my projectors 5 years ago, just before the 3D boom because projector manufacturers had very few extra gadgets to differentiate themselves and had to use the hardware to differentiate themselves from the competition. I had the choice between 1000€, 1200€, 1500€ and 1800€ projectors within the same line, all equipped with the exact same ultra-wide lens shift system with progressively better picture quality as the price went up. I had a golden opportunity to fine tune the quality/price ratio.

Nowadays, lens shifts tend to be only added on the mid to high-range. Manufacturers use other features to differentiate between sub 1000€ projectors and the start of lens shifts (3D, image processing, networking, wireless hdmi, etc...)
But since the price is much higher, if you do choose a projector with lens shift, you'll be aiming for projectors with significantly higher base picture quality (the price isn't only about the gadgets and the lens shift, manufacturers must also improve picture quality to justify the ridiculously higher prices).

If you are on a budget, you probably don't have a choice and should do without.
Thanx BlackShark for your info.

If I had to buy today I'd probably buy two of these.

http://www.projectorcentral.com/View...PJD7836HDL.htm

Street price new of $800 each

They are are bright enough for my application (3500 lumens) and according to the manual have about 11 inches of vertical shifting for a 150 inch screen. (mine is 120 inches horizontal) They also have the ability to do all those undesirable digital image tweaks like corner adjustment in case I end up having to do desperate things. For Omega-3D I may have to scale down the image size a bit so I can see the entire image in the glasses when sitting 10ft away but thats OK with me.

Does this model look promising?

Thanx in advance. :-)

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post #758 of 770 Old 12-17-2016, 01:45 PM
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It looks like a decent compromise. I had not noticed the small vertical lens shift. This will definitely help.
I don't think there is any competition for 3500 lumen at this price range, is it ?

One thing you need to remember : Light passing through the filters at an angle = bad. You'll want the projectors to be set up as far back as possible and use the optical zoom to it's fullest (if possible the projectors should be behind your seating position).
This means the projectors will have to be positioned high up close to the ceiling and upside down.
The top part of the projector isn't perfectly flat, so either you have to build a custom shelf to screw the projectors upside down on the ceiling, or you'll have to somehow find a way to level the projectors on a regular shelf.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)

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post #759 of 770 Old 12-17-2016, 02:24 PM
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Thanks BlackShark for checking out the Viewsonic. Yes, its very hard to find something that bright for <$1000. I think I've looked at all the models mentioned in projectorcentral's HUGE database. Truly a wonderful, helpful site, especially with the filtered search tool and positioning calculator. The Optoma EH416 looks promising at $899 street price too but I'm kind of stuck in the Viewsonic rut as the attached picture shows. That said, I do wonder which manufacturer makes a better machine and I suppose asking would be kin to asking "Which is better? Marvel or DC Comics?" Objective opinions may exists but I doubt they are the norm. :-) As for MY setup I'm already used to putting the projectors way in the back of the room upside-down against the wall. I'm very fond of threaded rods as an artistic medium and it shows in my constructions. In case you are curious, the image shows two 1024x768 projectors with polarizing filters in front of them for my current passive setup. my 1080p viewsonic 8200 is my main workhorse for most "regular" viewing. As you can see I'm used to the dynamics of mounting things on the ceiling. :-)

Thanks again for pushing those keyboard buttons. :-)
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post #760 of 770 Old 12-18-2016, 07:12 AM
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I think there is Something wrong with your setup if you can't watch long perioids At one seating....maby it's active ;D
I have no problems gaming hours and hours. And usually do my gaming At night. Even with omegas that have that small color balance difference between you don't get eye fatigue. Maby some nose fatigue as the glasses Are "heavy" compared to polarizers
With polarizers i can game as long as i want also with omegas if we Forget the nose problem. One other bonus with passive is the fact you always have backup projector and can Atleast Enjoy 2D when one projector fails. Or active 3D with capable projector. The geobox 501'a warp is pretty good if you buy LCD projectors with out lens shift and need some geometrical correction, I think geobox softens image less than prohjectors own keystone if it's not dlp .
I use geobox all the time for warped screen. And the difference in sharpness is so small I don't miss it.
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post #761 of 770 Old 12-26-2016, 10:08 PM
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Maby some nose fatigue as the glasses Are "heavy" compared to polarizers
With polarizers i can game as long as i want also with omegas if we Forget the nose problem.
I've been wearing regular prescription glasses for years now and have been inclined to mod them for one purpose or another. As for the heaviness on the nose, I wonder if there isn't a counterweight solution that could be applied behind the ears/head. 3d glasses already send our appearance into geeky-ville why not go all out and be comfortable. Just for the fun of it, I pressed down on the ends of my glasses stems and it releases all weight of the lenses on the front. It sure seems like counterweights could work for 3d glasses since our ears seem to happily take the extra weight. ( a whole lot better than a pair of balloons attached at the hinges, and probably better than attaching the frames to the brim of a hat. :-) )

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post #762 of 770 Old 05-28-2017, 01:35 PM
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Question

Hi everyone, I've been reading couple of 3D-related mail threads on this forum (very helpful!), but now I've come to the point when I cannot find the info I need by myself...so pls help

I'm working on choosing optimal components for somewhat exotic project of 3D screen in front of which viewer(s) should be able to move. So, no/minimal crosstalk is allowed when moving towards/out of edges of the screen and also no crosstalk when (reasonably) tilting your head. Brightness & color correctnes are not critically important.


After quite some research, I've come to the conclusion that dual-projector setup with Omega filters should give the best results (better then active or "classic" passive)



I've chosen these projectors: Optoma-HD29 Darbee (sorry, not able to post links)


Since this project is proof-of-concept, I'm on a pretty tight budget so unfortunately vertical lens shift projectors are too expensive (<1000$ per projector is max). I'm aware that I'll lose some picture quality because of need to use vert.keyshift to align picture from 2 projectors, but I hope that it will not be to drastic. The content to be shown is dynamic 3D render/gaming.


Because of the very specific room setup, this will have to be a rear-projection setup + screen.



Based on this setup, I have 2 questions:
  1. Is there any experience with dual-projector-Omega setup being used with rear projection? Anything I should consider/be worried about or some party-breaker I'm not aware of? What kind of screen to get? Any suggestions?
  2. Does this setup seem valid, anything I have missed?


Thanx in advance
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post #763 of 770 Old 05-29-2017, 12:24 PM
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Originally Posted by drobz View Post
Hi everyone, I've been reading couple of 3D-related mail threads on this forum (very helpful!), but now I've come to the point when I cannot find the info I need by myself...so pls help

I'm working on choosing optimal components for somewhat exotic project of 3D screen in front of which viewer(s) should be able to move. So, no/minimal crosstalk is allowed when moving towards/out of edges of the screen and also no crosstalk when (reasonably) tilting your head. Brightness & color correctnes are not critically important.


After quite some research, I've come to the conclusion that dual-projector setup with Omega filters should give the best results (better then active or "classic" passive)



I've chosen these projectors: Optoma-HD29 Darbee (sorry, not able to post links)


Since this project is proof-of-concept, I'm on a pretty tight budget so unfortunately vertical lens shift projectors are too expensive (<1000$ per projector is max). I'm aware that I'll lose some picture quality because of need to use vert.keyshift to align picture from 2 projectors, but I hope that it will not be to drastic. The content to be shown is dynamic 3D render/gaming.


Because of the very specific room setup, this will have to be a rear-projection setup + screen.



Based on this setup, I have 2 questions:
  1. Is there any experience with dual-projector-Omega setup being used with rear projection? Anything I should consider/be worried about or some party-breaker I'm not aware of? What kind of screen to get? Any suggestions?
  2. Does this setup seem valid, anything I have missed?


Thanx in advance
Hi drobz,

great that there are still people out there who are into 3D, since it seems to fade away...
I have a Omega Optical 3D setup with two Benq W1070 projectors (which has lens shift) and a GeoBox, and the system delivers a brilliant image. The contrast ratio of the Filters is about 1000:1 so you should not see any crosstalk at all, and i would highly recommend you this setup. There is no sensitivity to viewing angle or head tilt or position at all.

I never tried rear projection but in general there should be no issues (beside the commonly known rear projection issues like hotspot etc.). I would prefer front projection from the ceiling with a screen gain of 1.2, (1.5 maximum), but in your case i would try to get a rear projection screen with less hot spot as possible (depending on your budget).

There are some things you have to consider:
* The filters: These are interference filters so they are sensitive to transmission angle of light, in other words, you should use a throw as far as possible (minimum zoom), otherwise you will get color shifts and cross talk at the edges. Using the Benq w 1070 you must use minimum zoom). When you still want to use short throw, you must place the filters inside the projectors at a position where the light path is as parallel as possible. I put it behind the lens that follows the color rotation wheel. But this part is tricky, as there is very little space. And don't worry, the filters can handle high temperature, they originally have been designed for that purpose-

* The filter glasses transmit ~25% if the light, the rest is reflected, so try to make the room as dark as possible.

* Projector alignment is tricky, i used the 300$ Geobox with no 4 point perspective correction, and it took me 3 hours until I had only 1-2 pixels misalignment left, which is good enough at Full HD in my opinion.

* there may be some need for color correction, depending on the light spectrum of your projector. But most projectors have some kind of color adjustment menu. I projected a test image (windows color tiles) and played a bit with the sliders, but that's only for perfection.

Good luck with your project...
Best
Phil

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I do not see any major roadblocks for such a system to work.
I do however have some minor remarks :

A single projector DLP+ LCD shutter glasses system would be a much cheaper alternative for proof-of-concept / research purposes, unless you forgot to mention some particular technical requirements (resolution/refresh rates, or you figured that your application specifically requires simultaneous display in both eyes).

Since your viewers are expected to be moving in the room, I assume the room will have some amount of ambient light, just enough to make sure the viewers are able to see where they are going.
I would like to attract your attention on the possible ambient light problems :
- the filters are reflective. Any uncontained ambient light that reaches the viewer's face will reflect in the filters and the viewers will see the reflection of their own eyes.
Viewers will have to wear the glasses very close to their face. In my experience with ambient light, the integrated protections of the omega glasses are only sufficient for very low amounts of ambient light. If you add any type of extra light in the room, the viewers will require extra light protection (wearing a cap improves the situation significantly but is an extra accessory to deal with)
- the light spectrum of the light bulbs needs to be checked. An imbalanced spectrum will produce severe colour disparities between the viewers' eyes and make your system unusable. CCFL bulbs are particularly problematic.
LEDs vary a lot from model to model. Try to aim for wider spectrum bulbs (usually labelled as "high colour rendering index", "high light quality" or "natural light") you may get better results. But you should expect to do at least some trial and error for your light bulbs.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)


Last edited by BlackShark; 05-31-2017 at 03:43 AM.
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Originally Posted by philiwahnilli View Post
Hi drobz,

great that there are still people out there who are into 3D, since it seems to fade away...
I have a Omega Optical 3D setup with two Benq W1070 projectors (which has lens shift) and a GeoBox, and the system delivers a brilliant image. The contrast ratio of the Filters is about 1000:1 so you should not see any crosstalk at all, and i would highly recommend you this setup. There is no sensitivity to viewing angle or head tilt or position at all.

I never tried rear projection but in general there should be no issues (beside the commonly known rear projection issues like hotspot etc.). I would prefer front projection from the ceiling with a screen gain of 1.2, (1.5 maximum), but in your case i would try to get a rear projection screen with less hot spot as possible (depending on your budget).

There are some things you have to consider:
* The filters: These are interference filters so they are sensitive to transmission angle of light, in other words, you should use a throw as far as possible (minimum zoom), otherwise you will get color shifts and cross talk at the edges. Using the Benq w 1070 you must use minimum zoom). When you still want to use short throw, you must place the filters inside the projectors at a position where the light path is as parallel as possible. I put it behind the lens that follows the color rotation wheel. But this part is tricky, as there is very little space. And don't worry, the filters can handle high temperature, they originally have been designed for that purpose-

* The filter glasses transmit ~25% if the light, the rest is reflected, so try to make the room as dark as possible.

* Projector alignment is tricky, i used the 300$ Geobox with no 4 point perspective correction, and it took me 3 hours until I had only 1-2 pixels misalignment left, which is good enough at Full HD in my opinion.

* there may be some need for color correction, depending on the light spectrum of your projector. But most projectors have some kind of color adjustment menu. I projected a test image (windows color tiles) and played a bit with the sliders, but that's only for perfection.

Good luck with your project...
Best
Phil
Hi Phil,

sorry for the late feedback, I was out of country for 2 weeks...

Thank you very much on the info, the interesting part to me is the usage of Geobox for alignment. If I got it correctly, these boxes take the video signal in, warp the geometry and then push it out to a projector(s). But isn't projector's (vertical) lens shift "good enough" to be used for aligning image from 2 projectors? What concerns me is - the Geobox warps the signal "digitally" BEFORE the projector; it cannot alter the physical size/direction/warp of the image being projected from the projector, therefore it seems like the native pixel-on-pixel relationship definitely gets lost with the usage of such boxes, right? Are the projector controls too coarse to achieve pixel-on-pixel alignment? Will such a box be necessary if there's no physical lens shift? BTW; which box are you using, or actually which one should I be looking at, considering that the screen will be flat (not curved)?

Drobz
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post #766 of 770 Old 06-18-2017, 06:26 AM
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I do not see any major roadblocks for such a system to work.
I do however have some minor remarks :

A single projector DLP+ LCD shutter glasses system would be a much cheaper alternative for proof-of-concept / research purposes, unless you forgot to mention some particular technical requirements (resolution/refresh rates, or you figured that your application specifically requires simultaneous display in both eyes).

Since your viewers are expected to be moving in the room, I assume the room will have some amount of ambient light, just enough to make sure the viewers are able to see where they are going.
I would like to attract your attention on the possible ambient light problems :
- the filters are reflective. Any uncontained ambient light that reaches the viewer's face will reflect in the filters and the viewers will see the reflection of their own eyes.
Viewers will have to wear the glasses very close to their face. In my experience with ambient light, the integrated protections of the omega glasses are only sufficient for very low amounts of ambient light. If you add any type of extra light in the room, the viewers will require extra light protection (wearing a cap improves the situation significantly but is an extra accessory to deal with)
- the light spectrum of the light bulbs needs to be checked. An imbalanced spectrum will produce severe colour disparities between the viewers' eyes and make your system unusable. CCFL bulbs are particularly problematic.
LEDs vary a lot from model to model. Try to aim for wider spectrum bulbs (usually labelled as "high colour rendering index", "high light quality" or "natural light") you may get better results. But you should expect to do at least some trial and error for your light bulbs.
Yes, well noticed - single DLP + active shutter glasses would be a cheaper alternative for our PoC, but what concerns me is that I couldn't find relevant data about cross-talk levels in an "viewer-moving-around" scenario with single-DLP+active glasses setup. The viewer will be able to move beyond the left-right edges of the screen, and also quite close to the screen (0,5m). So the cross-talk is a major concern, and it seemed to me that Omega filters should handle it much better when the user is moving around - but that's just my interpretation of some inconclusive forum threads :-/

The info on the ambient light is very useful. I was wondering why the Omega glasses are so bulky with lots of plastic encasing the filters, so obviously blocking ambient light is the reason behind it. So I guess creating our own "slim-frame" glasses with Omega filters is out of the question :-/

Also very useful tips on the light bulbs, thanks!
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post #767 of 770 Old 06-18-2017, 06:35 AM
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Originally Posted by philiwahnilli View Post
Hi drobz,

great that there are still people out there who are into 3D, since it seems to fade away...
I have a Omega Optical 3D setup with two Benq W1070 projectors (which has lens shift) and a GeoBox, and the system delivers a brilliant image. The contrast ratio of the Filters is about 1000:1 so you should not see any crosstalk at all, and i would highly recommend you this setup. There is no sensitivity to viewing angle or head tilt or position at all.

I never tried rear projection but in general there should be no issues (beside the commonly known rear projection issues like hotspot etc.). I would prefer front projection from the ceiling with a screen gain of 1.2, (1.5 maximum), but in your case i would try to get a rear projection screen with less hot spot as possible (depending on your budget).

There are some things you have to consider:
* The filters: These are interference filters so they are sensitive to transmission angle of light, in other words, you should use a throw as far as possible (minimum zoom), otherwise you will get color shifts and cross talk at the edges. Using the Benq w 1070 you must use minimum zoom). When you still want to use short throw, you must place the filters inside the projectors at a position where the light path is as parallel as possible. I put it behind the lens that follows the color rotation wheel. But this part is tricky, as there is very little space. And don't worry, the filters can handle high temperature, they originally have been designed for that purpose-

* The filter glasses transmit ~25% if the light, the rest is reflected, so try to make the room as dark as possible.

* Projector alignment is tricky, i used the 300$ Geobox with no 4 point perspective correction, and it took me 3 hours until I had only 1-2 pixels misalignment left, which is good enough at Full HD in my opinion.

* there may be some need for color correction, depending on the light spectrum of your projector. But most projectors have some kind of color adjustment menu. I projected a test image (windows color tiles) and played a bit with the sliders, but that's only for perfection.

Good luck with your project...
Best
Phil
Hi Phil,

thank you for the feedback, it's very useful, and also sorry for the late reply, I was out of country for 2 weeks...

Could you please elaborate some more the usage of Geobox for video processing? It's hard for me to understand the issues that arise when trying to align images from 2 projectors. Is the usage of video-processing box necessary or does it only make the alignment process easier? What if the projectors don't have (vertical) lens shift, is then such a box a necessity? And even if they do have lens shift, are the on-board lens shift and keystone corrections too coarse to align images? Or are these video processing boxes used only for curved screen setups (we will be using flat screen)?

Drobz
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post #768 of 770 Old 06-21-2017, 11:33 AM
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Originally Posted by drobz View Post
Could you please elaborate some more the usage of Geobox for video processing? It's hard for me to understand the issues that arise when trying to align images from 2 projectors. Is the usage of video-processing box necessary or does it only make the alignment process easier? What if the projectors don't have (vertical) lens shift, is then such a box a necessity? And even if they do have lens shift, are the on-board lens shift and keystone corrections too coarse to align images? Or are these video processing boxes used only for curved screen setups (we will be using flat screen)?
You do not need lens shift, but lens shift makes it easier and allows you to keep the full resolution. (keystone correction does reduce resolution).

Lining up 2 projectors for acceptable 3D is easy. You can do it in 5~10 minutes. But the misalignment will be obvious as soon as you take the glasses off.
Lining up 2 projectors for great 3D is difficult. It takes about 1~2 hours. The misaligment will look like a small amount of blur if you take the glasses off, you'll need to get up close to the screen to understand there is a misalignment.
Lining up 2 projectors to pixel perfection is INSANELY HARD ! Especially with the very coarse controls of consumer projectors. (I cannot achieve it with my current projectors)

This is where processing come to the rescue. You can do an approximate alignment with the coarse projector controls, and fine tune with the digital processing.
Yes, it is software correction, yes it lowers the amount total usable pixels. But with high quality scaling devices, it's fine.
The basic Geobox 300 series does not have warp correction.
The advanced Geobox 500 series has the feature. It's costs double the price of the basic one.
I have the Geobox 501 with warp, but I do not use it (I have this box because I wanted to ensure compatibility with both AMD and Nvidia graphics cards, and wanted to have both DVI-Dual-Link and DisplayPort input capability)

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Originally Posted by drobz View Post
Yes, well noticed - single DLP + active shutter glasses would be a cheaper alternative for our PoC, but what concerns me is that I couldn't find relevant data about cross-talk levels in an "viewer-moving-around" scenario with single-DLP+active glasses setup. The viewer will be able to move beyond the left-right edges of the screen, and also quite close to the screen (0,5m). So the cross-talk is a major concern, and it seemed to me that Omega filters should handle it much better when the user is moving around - but that's just my interpretation of some inconclusive forum threads :-/
DLP + active shutter glasses has very similar crosstalk characteristics to Omega.
You have almost zero crosstalk regardless of your position in the room, but it does have some crosstalk if you looks through the glasses sideways (near the edges of the lenses).

There is a technical issue you need to be careful about if you use shutter glasses, especially since your viewers will be moving around the room.
Shutter glasses can synchronize with the projectors according to 2 methods :
- light (Infrared or visible light)
- radio waves (RF or Bluetooth)
If using the light transmission system, the glasses will loose signal when your viewers turn their heads away from the screen or if an object passes in front of the viewer and blocks the view from the glasses receiver to the screen. This will lead to uncomfortable desynchronizations and waiting a fraction of a second to resynchronize when turning their heads again towards the screen.
Radio wave transmission is much better since it goes around or through furniture and people. The glasses connection will be maintained even if viewers turn their heads away from the screen. I recommend you make sure you have radio wave transmission synchronisation of the glasses.

When you looks for a projector, double check if it has either built-in RF transmitter, and which format it uses. Some use Bluetooth, some use open RF protocols, some use proprietary RF protocols.
Some projectors are not equipped with a transmitter but have a standardized VESA 3D-sync output, onto which you can attach a standardized 3D sync transmitter. (in which case you can choose your own equipment)
The range of the radio transmitter may be a technical requirement you'd want to check, depending on the size of the room you plan to use and how far your viewers will be from the projector/transmitter.

If you use Omega, then they'll just work throughout the room.

Passive 3D, forever !
My Full-HD dual-projector passive polarised 3D setup. (really out of date ! I need to update it some day...)

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post #769 of 770 Old 06-21-2017, 11:39 AM
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Trapeze has a very high influence on 3D and must be corrected for 3D to look good !

The most efficient correction is vertical trapeze correction (it's due to the geometry of 99.9% of projectors, they're built wider than tall, so you have less correction to do if you stack them vertically)
Also, most projectors only provide vertical trapeze correction, only a few provide both horizontal and vertical trapeze correction.

The most important issues with using trapeze correction are :
-image quality (trapeze require scaling, it's a minor annoyance on most content, only an issue if you're doing computer games with tiny text or if you want every single pixel on the matrix intact, like me)
-setup complexity (this is the biggest one for dual-pjs : position of the projectors in the room, tilt, zoom and the amount of correction of both projectors are all interdependent, change one single parameter and all the others change, you'll spend a lot more time setting your projectors up)

At the moment, I haven't seen any projector manufacturer providing a lens shift on a cheap entry level projector like Epson used to do a few years ago.
I wouldn't even think of going passive dual projection without lens shifting projectors. All other geometry processing set to off. You can buy many projectors with lens shift from the 500 dollar w1070 to midrange PJs, and of course most high end ones too. It's just important to make sure before you buy, but they're available.
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Originally Posted by BlackShark View Post
You do not need lens shift, but lens shift makes it easier and allows you to keep the full resolution. (keystone correction does reduce resolution).

Lining up 2 projectors for acceptable 3D is easy. You can do it in 5~10 minutes. But the misalignment will be obvious as soon as you take the glasses off.
Lining up 2 projectors for great 3D is difficult. It takes about 1~2 hours. The misaligment will look like a small amount of blur if you take the glasses off, you'll need to get up close to the screen to understand there is a misalignment.
Lining up 2 projectors to pixel perfection is INSANELY HARD ! Especially with the very coarse controls of consumer projectors. (I cannot achieve it with my current projectors)

This is where processing come to the rescue. You can do an approximate alignment with the coarse projector controls, and fine tune with the digital processing.
Yes, it is software correction, yes it lowers the amount total usable pixels. But with high quality scaling devices, it's fine.
The basic Geobox 300 series does not have warp correction.
The advanced Geobox 500 series has the feature. It's costs double the price of the basic one.
I have the Geobox 501 with warp, but I do not use it (I have this box because I wanted to ensure compatibility with both AMD and Nvidia graphics cards, and wanted to have both DVI-Dual-Link and DisplayPort input capability)
Very helpful, thanks. If we decide to go with dual-projector setup, we'll include a Geobox 500 series box.

Quote:
Originally Posted by BlackShark View Post

DLP + active shutter glasses has very similar crosstalk characteristics to Omega.
You have almost zero crosstalk regardless of your position in the room, but it does have some crosstalk if you looks through the glasses sideways (near the edges of the lenses).

There is a technical issue you need to be careful about if you use shutter glasses, especially since your viewers will be moving around the room.
Shutter glasses can synchronize with the projectors according to 2 methods :
- light (Infrared or visible light)
- radio waves (RF or Bluetooth)
If using the light transmission system, the glasses will loose signal when your viewers turn their heads away from the screen or if an object passes in front of the viewer and blocks the view from the glasses receiver to the screen. This will lead to uncomfortable desynchronizations and waiting a fraction of a second to resynchronize when turning their heads again towards the screen.
Radio wave transmission is much better since it goes around or through furniture and people. The glasses connection will be maintained even if viewers turn their heads away from the screen. I recommend you make sure you have radio wave transmission synchronisation of the glasses.

When you looks for a projector, double check if it has either built-in RF transmitter, and which format it uses. Some use Bluetooth, some use open RF protocols, some use proprietary RF protocols.
Some projectors are not equipped with a transmitter but have a standardized VESA 3D-sync output, onto which you can attach a standardized 3D sync transmitter. (in which case you can choose your own equipment)
The range of the radio transmitter may be a technical requirement you'd want to check, depending on the size of the room you plan to use and how far your viewers will be from the projector/transmitter.

If you use Omega, then they'll just work throughout the room.
Hmmm, this info makes me re-think the basic setup for our proof-of-concept. If the cross-talk levels with active 3D glasses are very similar to Omega passive glasses, than it makes more sense for us to use single DLP projector with active glasses. It would allow for us to use short-throw projector, which would be quite useful (less required space behind the screen). More importantly, Omega glasses are very bulky because they require blocking as much ambient light as possible to reach user's eyes, which is not the case with active glasses (OK, active glasses are heavier). It would allow us to have higher level of ambient light.

Also, thank you regarding feedback on radio vs light sync for glasses, very useful info. Radio seems like a much better option.
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