Single projector passiv 3d - Z-Screen

[noos]

Hello,

as you know, there are two ways for passive 3d (non active non shuttering "sun" glasses - like in cinemas):

- using two projectors and polarization filters in front of the projector

- using a z-screen in front of the projector (like cinemas do)

I planned to do the first solution in the future, so I am way behind in building my curved high gain silver screen - because as you know - you need a screen that keeps the light polarization. So it should be a silver like screen, that should be curved because of hot spotting, or you use a rear projection screen that has this specific feature.

But I now got this type of Z-Screens for CRT monitors:

http://www.mfb-geo.com/spip.php?rubrique83

http://www.ebay.de/itm/330615718969?ssP ... 1423.l2649



These tools are rare, and I was looking for them quite some time before I found some I could afford.


As my curved silver screen is a distant dream, I did build a rear projection screen for testing the Z-Screen with a Sony 1272 CRT projector. (For 7" AC an 8" LC machines one Z-Screen is fine. With 8" AC or 9" you should use two Z-Screens.)

I did test these screens with crt monitors, and as the Barco pdf shows, they have a little more ghosting and are a bit dimmer than shutter glasses solutions. As you know, you can avoid green ghosting with non P43 phosphor by adding more inactive lines to picture with Powerstrip, the Nvidia customized resolutions, or Lumagen Radiance scalers. So I needed to add a little more front and back porches than with shutter glasses to eliminate green ghosting.


I was able to use also the cinema glasses from Avatar....

The screens accept the standard 3d sync signal. But, my rear projection screen does not keep the polarization (solutions welcome - curve preferred), so I will get me a different material or build the curved silver screen an update the process here.

I guess these screens should also work with digitalis that are not polarized like LCDs are (DLPs?)...?


The seller has some of them left on the shelves. They cost a fraction of their high 4 digits price in the nineties - and I will ask him if I can post his email here for contact.

... I kept my writing short, as I will update my findings when I found a screen material that keeps polarization.

Regards

Marc



Ps: I have permission from the seller now:




mark_frnka@comcast.net



You can write to him, but in the subject you should mention Z-Screens. He is selling medical equipment, so I guess these screens were intended to use in 3D applications in an hospital or clinic, but never were used. He has a couple of these Z-Screens, and they are all brand new an in the original package. They come with cables and controller plus three passive glasses. But you can use the cinema glasses, so I guess these screens a circular polarized. I fear that day when I will have to buy circular polarized sheets for a dual projector setup with CRTs ($$$). Considering this, the condition of the screens, the insane prices some companies (that have probably misses digital revolution) ask for these screens, and that they are rare like hen´s teeth - 150$ for one screen is a steal. I am sure the seller will give you two for 250$. He is located in the US, but he is shipping worldwide. He did pack two screens for me in one original package, and shipped it to Germany for 63$.



Regards


Marc

[Fredz]

Nice that you got this working. I've got one question though, isn't the heat produced by the lamp of the projector dangerous for the Z-Screen, I guess they weren't designed for that much heat ?

Also, I think you've forgotten one possibility for passive polarized 3D projection, the spinning polarized wheel as used by Masterimage. I don't know if it's affordable or easy to build as a DIY project though.

[cybereality]

Awesome find man! Is the 3D as good as the cinema?

[noos]

Hello,


no there is no heat!


Between the (cathode ray) tube and the Z-Screen are the lenses. They (the lenses) are about 5" to 10" thick - glass, metal and plastic. Room temperature for the screens....Also the tube face is only warm, because there is glycol in the front for cooling.
I am not experienced with digitals, but I think a few centimeters away from the lens should be no heat anymore. I might try a 85 HZ DLP in the future with this screens, but I am not sure I will get it (the DLP) for tests. I am pretty focused on CRT projectors...


It is circular ($$$) polarization with this Z-Screens, so you can tilt an move you head like in cinemas - there is no "extra" ghosting.

If you have eliminated ghosting with P43 phosphor, or invisible extra porches or lines in the picture, it is great! If you could use them with fast/non ghosting digital (like in cinemas), it would be the same like in cinema


Best regards and thanks for your input



Marc

Ps.: I knew about the light/spinning wheel - thanks for adding! But I was not able to implement this for my 3 gun CRTs, so I dropped it from my hard disk.

[noos]

...probalby it is possible to force one Z-Screen to permanent left eye polarisation, and an other one to permanent right eye polarisation. Then you clould also use them in a dual projector setup, and do not have to buy circular filters...

[noos]

Hello,

the seller of these screens is now on Ebay. I am sure he has more than this screen:

http://www.ebay.com/itm/250902929575?ss ... 1558.l2649" onclick="window.open(this.href);return false;

I will go for this material to build my rearprojector:

http://www.nexnix.co.uk/3d/3d_projectio ... terial.php" onclick="window.open(this.href);return false;

Best regards

Marc

[cybereality]

Thanks for posting this. I'm sure someone will be interested.

[mAchiNE]

Thanks for this! I saw one of those Z Screens on ebay a while ago, I might grab one of these and see if it can work with my 120Hz DLP Projector for when I have people around for movies, I already have a Sony Silverscreen (designed to improve ambient light viewing not for 3D but quick testes show me it might work for polarised 3D)
A quick question, how do you drive the ZScreen? can it run off modern computers?

EDIT: I see it needs a Sync signal like on the old 3D TVs? My DLP Projector does not have this sync signal so unless there is a converter that can get the sync signal from either the HDMI or VGA port or possibly convert the DLP flash used for DPLink glasses this is on no use to me... Any one have any suggestions about how to do that?


Also

Hi there, on this racing forum they have been experimenting with using aluminum sheets as silver screens:
http://www.x-simulator.de/forum/polariz ... 6-130.html" onclick="window.open(this.href);return false;
They have had good results from a thin sheet of anodized aluminum, its a long thread so the link I put goes straight to the page with the info about the anodized aluminum sheet he is currently using.

(from this thread:http://www.mtbs3d.com/phpBB/viewtopic.p ... 2&start=15)

[noos]

Hello,

I missed to add the correct photo of the sync cable. It is like this one:

http://www.3dflightsim.com/product/extender1.jpg" onclick="window.open(this.href);return false;

But one end is BNC for the controller device, the other vesa standard. It is the standart 3 pin cable that also the modern nvidia dongle uses. No problem for the screens, they are professional units, that take any sync known to me via the vesa cable. For the sync, you can use the DVI SYNC Spliter Dongle from this page: http://www.3dmagic.com/" onclick="window.open(this.href);return false; It extracts the sync from a DVI or HDMI signal! But you can also use the Moome EXT 3D. It can do a lot more, plus will put out a sync at any refresh rate!
Let me know or ask more

[noos]

I can not add the correct picture of the cable, so I uploaded it somewhere else:

http://s7.directupload.net/file/d/2681/l8csrs94_jpg.htm" onclick="window.open(this.href);return false;


And thanks to a hint on a german stereo forum, I was able to test the Z-screens on a projection screen covered with Aluminium foil. Terrible hot spotting, but the polarisation was right and ghosting free, except for some of the slow green decay, but that I will stop by adding porches and blank lines to the resolution.

If someone tests these Z-screens with digital projectors, let me know if the timing of the sync is right.

[Fredz]

Would your technique of adding porches and blank lines work for CRT monitors instead of CRT beamers ? Because I've tried that already to diminish green ghosting on my CRT monitor but it didn't work. Can you explain how you do that in more details ?

Thank you.

[noos]

Hello to France!

If you like to know more than I can explain, than try to google "lumagen" and or "radiance" plus "3D" and/or porches. These are video processors than can be programmed to change any resolution and refresh rate to the customized anti ghosting resolution. This process can also be done with powerstrip or (disliked by me) with the NVIDIA cust. resolutions driver option.

For sure I am using this also on CRT monitors!

It is all about giving the green tube more time to let the old picture decay. Therefore you add blank vertical (!!!) lines/ inactive lines to the picture. These lines are in any signal, but you will increase them, so that there is a longer blank period after and or before the next picture. So that is the basic idea that I never was able to use with success, until I found the following info: Move the picture with the front and the back porches into the shutting period of you glasses! So normally you are completely ghosting free with an extra of 450-550 blank lines at 720p at 100hz (120hz or higher will need a little more lines, but your CRT must be able to handle huge resolutions). So I was adding anything between 100 and 500 lines, equally mixed between vertical front and back porches and some sync width - no good success, some probably. In my case, I need for a Sony rear projector 380 on front, 80 back porches and some (40) sync width. I simply start with increasing one porch until I reach 300-500( and I am also forced to in increase horizontal back porches to keep the picture in position), than I look at the 3d picture, and I still notice ghosting (( But look close than, it will only be at (for example) one half/third of the upper picture. So than go back to powerstrip and give some numbers to the opposite porch. You will see that the ghosting area moves - so than move it out until you are ghosting free. It was like magic when I saw the first time a clean picture!!! I used Mirrors Edge starting camera over the buildings at the beginning of the game - clean! Mirrors Edge is the number one ghosting title I know. Please recommend me another hard one for tests...
Back to resolution fitting. You will very soon find out what your crt needs where. And at what resolution the picture can still be fully stretched by the screen, because the monitor thinks that the black lines are active picture. That´s why I skipped 848x480 or 1066x600 - the more active horizontal lines, the more inactive ones you can add! If your screen has no size problems, you also do high interlaced resolutions like 1600x1200i or 1920x1080i at 100hz - plus porches you will be less than 100khz. My 1280x720 at 100hz plus porches is a 115khz signal! Make sure the game uses the resolution, so set you desktop with powestip in that resolution. Than powerstip should do the rest when the game starts with the same res. as the desktop (but you can support it with "refresh lock", a great program). But normally powerstip does everything, even when it is minimized in the background!


Should I make this a new topic?

Thats all for now, feel free to ask

Best regards from Munich

Marc


..I still use mostly the old Asus glasses when using shutters, but I am looking for a emitter for the Nuvision 60gx or a multi emitter or the xforce3d glasses or the Anothereye2000 glasses or a emitter for the xpand 101....preferred in Europe.

[Fredz]

Danke Schön !

Much appreciated, I did try already with custom resolutions in the NVIDIA driver but without success, I'll try with your advices and PowerStrip. I'll probably post before-after pictures to show the results if the ghosting is reduced.

I think Mirror's Edge is a very good test indeed, I don't have it installed on this PC (installed on the one connected to my DLP projector) but I'll try with other games and movies, and with the DDD ghosting test.

And yes, I think this could be a great subject for a new topic. Even if not a lot of people are still using CRTs, it should be very helpful for them anyway. I heard about this technique on other forums with people using Sony G70 and G90 CRT beamers (http://www.curtpalme.com/forum/viewtopic.php?t=28398" onclick="window.open(this.href);return false; and http://www.cinetson.org/phpBB3/tritubes ... 33323.html" onclick="window.open(this.href);return false; ), but I could not reproduce their results. It would be nice to have a definitive and more detailled reference about this subject on MTBS3D.

I'm currently using Elsa Revelator and eDimensional glasses by the way. I also have SimuleyesVR but they are collecting dust for now.

[tritosine5G]

Wow, those glasses are old . Check out this attempt at shutterglasses, hopefully can be bought seperately, not everyone is sold on "super DLP" and "LightBoost" and " Passive beyond Active " : P
http://translate.google.com/translate?h ... review.htm" onclick="window.open(this.href);return false;

I think it must be lot better quality than ordinary LC , or passive filters, but still not "neutral density" ( polarizers have colorshift...). Plus, you can use that 120hz per eye trick with 2x cheap projectors as well , using time interleaved method.

[PalmerTech]

They are old because this thread is about a device that is nearly 20 years old. Stay on topic, please.

[noos]

Right, my only information came from the Curt Palme site, as this is a source for information on my CRT projectors. There a two threads...

The one you mentioned helped me the most, here is the key post edited by
me with "*":
....

720p 96Hz
Vtotal 1270* Somewhere the lines must be, I guess Vback 420!
Vactive 720................................................... (Vactive) + 720
Vfront 125......................................................(Vfront) + 125
Vsync 5...........................................(vsync/syncwidth?)+ 5
.....................................................................(VTotal)=1270
Vtrate 95.9
Htotal 1600
Hactive 1280
Hfront 80
Hsync 40
Clock 194877123

The more vertical blanking the less ghosting... that is assuming you can make adjustments to your glasses timing.

If you can't adjust glasses timing delay, what you will need to do is adjust the vertical front or back porches to move the active image inside the total pixels such that it aligns with the glasses timing transition. Moving the active image may not work however because your projector may not have enough centering control range to compensate.

craigr


...that was the best post I ever found!
But on Curt Palme is another thread, 18 Pages and only some info hidden:

http://www.curtpalme.com/forum/viewtopi ... hlight=g90" onclick="window.open(this.href);return false;

It was much easier to do that on a CRT Monitor than on a CRT projector. When ever I change one parameter, I have do redo convergenz to a certain part or move the picture back on the screen via the setup menus of the projector.

Have fun and install the Mirrors Edge Demo...

[noos]

...here is one of these sync extractors from a digital signal: http://www.ebay.de/itm/150685406546?ssP ... 1423.l2649" onclick="window.open(this.href);return false;

[noos]

Hello again, and here are two devices that split a 3d HDMI superframe in a 100/120hz VGA signal plus standard sync for the Z-Screens! Please google 3d + fury, moome + 3d.



You can also google for 3d VIP, as this one also changes the refresh rate to 50/60hz, so that 3d runs on standard 2d screens

[Woody]

"mAchiNE" said: Thanks for this! I saw one of those Z Screens on ebay a while ago, I might grab one of these and see if it can work with my 120Hz DLP Projector for when I have people around for movies, I already have a Sony Silverscreen (designed to improve ambient light viewing not for 3D but quick tests show me it might work for polarised 3D)

A quick question, how do you drive the ZScreen? I see it needs a Sync signal like on the old 3D TVs. My DLP Projector does not have this sync signal so unless there is a converter that can get the sync signal from either the HDMI or VGA port or possibly convert the DLP flash used for DPLink glasses this is on no use to me... Any one have any suggestions about how to do that?

---------------------------
I bought one the the Z-screens on eBay, and am experimenting to see if I can use it with my Optoma GT720 3D DLP projector. I have the same lack of a 3D signal out from the projector. I tried using a 3DXL unit, which has an "IR Output" 3-pin jack, but that did not work.

What I've done so far is to connect the Z-screen to the 3D out signal from my rear-projection DLP 3DTV set, and then look through the Z-screen at the TV while wearing the passive glasses. I note that the disposable RealD glasses that theaters hand out work fine with this. Only the bottom half of the Z-screen was properly functioning for me. (That will not affect my intended use very much, I can project if need be only through the bottom half.) I am guessing that this may be because the refresh timing of a DLP TV is different from the refresh timing of a CRT. I will try introducing an adjustable delay in the 3D sync signal before it gets to the Z-screen driver box, and see if I can make the entire Z-screen work with my TV set.

I saw some ghosting in high-contrast scenes, but I suspect that this is normal. I have no illusions that this Z-screen will work as well as the newer Z-screens used in theaters. I was pleased to see that the off-axis performance of the Z-screen is pretty good - tilting the Z-screen doesn't hurt the polarization very much through 30 degrees or so (estimated - I did not measure this). I might not be able to get good results with my GT720 projector, because is is a short-throw projector and I calculate that it has a maximum angle at the edges of almost 35 degrees.

For experimentation, I'll split the HMDI signal out of my 3D Blu-ray player using an HDMI distribution amp, and feed both my TV set and the projector, and then use the 3D signal out of my TV set to drive the Z-screen. If it works OK, I'll sacrifice a pair of DLPLink glasses to try to make a 3D sync signal generator. I'm definitely concerned about heat from the projector, but I have a hot mirror that I can put in the beam path at 45 degrees, and maybe that will handle the problem.

[noos]

Hello,

and thanks for that report on DLPs! The Optoma sync port is dead, as far as my short google check showed. Sorry...: http://www.mtbs3d.com/phpbb/viewtopic.php?f=122&t=12918" onclick="window.open(this.href);return false;
There are many other devices to get a sync, please look at my posts. 3D VIP, 3d Fury, Moome3d or if only sync than this one: http://www.ebay.de/itm/HDMI-DVI-3D-SYNC ... 25694f0ec5" onclick="window.open(this.href);return false; ...also available on 3dmagic.com

Well, ghosting is also created by the projetion screen or rearprojection screen, if light loses the polarization there. I did test with the rear side of aluminum foil, as this is ideal case for polarization. Perhaps you can test it too, because than you see how much ghosting comes from the screen itself.

But you should def. get at first a good sync signal that is not altered or generated by a diffrent viewing device.
On analog screens I added blank lines to the picture to move it into the perfect sync of shutter glasses or Z-screens. Will not work for digitals I guess. The sync box of a Lumagen Radiance can change the timing, so I guess the is not rocket sience. Perhaps there a solutions on the market yet, like with the Moster RF glasses. They can control the timing too. Do you have an idea for a circuit that delays sync?
This was just fast thinking one you results, I will add more thoughts about your great project!
Marc

[billqs]

I also picked up ones of theses Z-screens on ebay. I could not find the dvi sync splitter on ebay and the 3dmagic guy said ebay is the only place he sells these, so I ordered the earlier edimensional vga sync dongle, but couldn't get the screen to sync. I bought a $5 old silver screen from Salvation Army and I got circular polarized rotation viewing with polarized glasses, but it would not hold sync to each eye.

Is anyone familiar with edimensional VGA dongle? I used the Vesa 3 prong plug out that the edimensional IR transmitter uses, but never got the green light indicating sync had been achieved.

I am using the Open ATI/AMD HD3D with a 6850 graphics card. I don't have any edimensional software installed, could this be the problem? I am getting 3d from my projector using TMT3 with 3D plugin and I assumed the signal created to drive the IR transmitter would also drive the Z screen.

Thanks for any help.

[noos]

You are welcome! I have linked to the 3d sync extractor above on Ebay. For sure after weeks the auction is not valid anymore. So then click on the seller other items, and ther you will find this one today: http://www.ebay.de/itm/HDMI-DVI-3D-SYNC ... 256a0e18c1" onclick="window.open(this.href);return false;
...ooops, now I did that fpr you.

ED dongle, like the old ELsa dongle need to be activated! The ED Dongel by a program, and the Elsa dongle by a signal from Nvidia cards. So with ATI you need a digital sync extractor like the one above. Or you can try the ED activator, but I have no idea if it works in your computer

[billqs]

Thanks for the reply, noos! Does the seller speak English? I don't speak German but from what I can tell, he doesn't advertise shipping world-wide. I will try to send him a question through ebay.

So, for the dongle I have, I would need to download the ED Activator and see if that worked. Thanks for your help.