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 Projectors and 3D and Ghosting/Flicker Removal 
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Binocular Vision CONFIRMED!
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OP 28/05/2007

A lot has been already covered in other places. I will not add every piece of information there is on projectors on here.

Instead, this will be a short introduction into projectors and an overview of potential problems.


Let me introduce myself. I have been into stereo gaming since I first heard the word "shutter glasses". I have had many stereo setups including normal monitor, Head mounted display, and Projector.

I can, then, wholeheartedly say that out of all, projection was by far the most "Wow"-ing.

Projectors project a large image onto a screen (duh!). When you play on a CRT or even an HMD, the perceived screen size is too small for a "lifelike" size and feel.
In my opinion; on a small screen compared to a larger screen, the smaller screen always gives the impression that you are playing with small toy models rather than a simulation in real life. This is especially noticeable in FPS games.
On a projector, your gun is life size; your enemies are life size. When you stand and look down a corridor in 3D, you ARE actually looking down a corridor - There is no ghosting or other perspective artefacts.
Your focus is also further away at the screen, which means that there is practically no strain.
On top of that, you can watch all your movies and TV shows on your expensive investment.


Wow! That sounds amazing... what's the catch?

There are a few catches. Firstly, there is the initial cost of the projector and the maintenance cost ie bulbs. My projector bulbs last 1000 hours (read a couple of months) and cost ?470 to buy, although I believe that this is the very high end in pricing.

Secondly, not all projectors are stereo compatible. Only DLP projectors work in stereo, and then only a few. There are lists of which do work at other places.
The ones that do work sometimes do not sync perfectly, so you get ghosting. The good news is that this is not like the ghosting on a CRT and can be 100% eradicated.

Thirdly, brightness is always an issue. Projectors just arn't bright enough for shutter glasses use as shutter glasses block out 76% of the light. You have to compensate by notching up the gamma and vibrance settings.

Taking all this into account, if you are looking for the ultimate stereo experience, projectors are the only way to go, followed closely by HMD.

Playing games like half-life2, you really do feel that you are there.

Finishing up on a few tidbits...

If you have the money, you can invest in a dual projector setup. Each projector displays a seperate image from a separate perspective (think i-max). No need for shutter glasses. With the use of polarising lenses and a special screen, you can view with cheap polarized glasses.

There are threads around the internet which list which projectors are compatible; which, if people are genuinely interested, I can hunt out.

Here is one:
http://forums.stereovision.net/viewtopi ... 89&forum=2

About the bulb, there is a workaround. I have modified my projector electronics to make it accept a bulb and control gear of my own choosing at a fraction of the cost.

A hardware solution and premise for projector ghosting removal that I made can be found here:

Image
Image
Image

As always, I am available for help with any stereo related problems on MSN.

Edit 1:

28/1/2008

This circuit can be converted to a flicker removing circuit quite easily. This particular flicker I refer to is the one you sometimes get every few seconds on random occasions - some people more than others - which is very annoying. The flicker pulls you out of the 3D world and the "suspension of disbelief" is shattered thereby detracting from the experience.

The flicker occurs because the graphics card fails to send an appropriate DDC signal to the emitter. We have to then make our own signal to compensate.

The best way to do this is to use a 50% duty cycle oscillator at the refresh rate you are playing at. Simply connect the 555 timer in oscillation mode (instead of delay mode shown above) using the appropriate resistor/capacitor combination from the data sheet of the timer. Now connect the DDC signal to the RESET pin of the oscillator and the output to the emitter and calibrate to 50% duty cycle at your refresh rate.

Now, what will happen is the falling edge of the DDC signal will continually reset the oscillator thereby keeping the glasses in sync with the refresh rate AND the oscillator will continually produce a square wave. In the event that the signal dies on the DDC line, a reset is no longer triggered and the oscillator will still give an almost perfect square wave keeping your glasses functioning perfectly. The flicker from DDC signal corruption will be completely eradicated as now, whenever the DDC signal is corrupted, the oscilator will take over.

Of course this also means that the glasses will keep on working even out of stereo, so don't forget to turn them off if they run on batteries ;P


-- Shahzad Ali
Cambridge
England, UK

Edit 03/04/2009

Fixed broken links.


Last edited by RAGEdemon on Fri Apr 03, 2009 9:34 am, edited 4 times in total.



Sun Mar 11, 2007 7:41 am
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3D Angel Eyes (Moderator)

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How much would this setup cost, do you think? I probably won't be able to do this anyway in my house (my wife says if I want the projector setup, we need to get a new house!) but am curious about how much it costs. I wish I lived near you to check it out!
-Nate


Sun Mar 11, 2007 12:11 pm
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Binocular Vision CONFIRMED!
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Just the cost of a 3d compatible projector, shutter glasses which are about 15$ on eBay and a stereo compatible nVidia card.

The projector you choose should be as bright as possible. Also might be an idea to invest in a high gain screen. Currently, I have a 2:1 gain screen with a 1100 lumen projector which gives decent results. Total cost ~$1200, but im sure you can get things for alot less nowadays.

Might be an idea to setup on your CRT first and see if you like what you see. It does involve alot of tweaking and I would hate to have your wife mad at me :)


Sun Mar 11, 2007 2:41 pm
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Certif-Eyable!
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A projector setup and Dolby Digital/7.1 sound system would blow anybody away I guess. Are these setups displayed at the E3 and similar shows? If so I foresee a boom in S-3D.
How do a projector setup work with headphones (X-Fi soundcard)? I'm thinking if this "destroys" the "I'm there" experience? I can't play loud in the evening, and I need to hear when the gamers sneak up on me.
Imaging being knifed in BF2 in S-3D in lifesize...scary thought :shock:


Mon Mar 12, 2007 12:19 am
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Two Eyed Hopeful
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My university has a VR setup with dual projectors and a VERY expensive Disney Black rear projection screen (HUGE!). Since it is for VR, it has motion tracking, etc etc, run through a few servers running Red Hat Linux. Total cost: ~$50,000.

And yes I am in a class that can use it freely and yes again I am making VR games! :D


Mon Mar 12, 2007 10:44 am
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One Eyed Hopeful

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Freke1 wrote:
A projector setup and Dolby Digital/7.1 sound system would blow anybody away I guess. Are these setups displayed at the E3 and similar shows? If so I foresee a boom in S-3D.
How do a projector setup work with headphones (X-Fi soundcard)? I'm thinking if this "destroys" the "I'm there" experience? I can't play loud in the evening, and I need to hear when the gamers sneak up on me.
Imaging being knifed in BF2 in S-3D in lifesize...scary thought :shock:


I play alot of BF2 in 3d on my projector. I play it both in surround sound and with headphones. Both are great. The size of the screen gives it that "I'm There" feeling


Wed May 23, 2007 8:12 am
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Two Eyed Hopeful
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I wish I could find the link, but I just read that a LED powered DLP RPTV is at CES this year. This is potentially the best new option for big screen stereo as it does not require a color wheel. The unit I read about has an input that will take supports over 100Hz (120Hz if i remember correctly). similar front projectors can't be far behind.

Edit: Heh, it was over at the nVidia site, so most of you probably already know about it.

http://forums.nvidia.com/index.php?s=2faf9a5940f9c29ab24eba6445bf2869&showtopic=36332

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Wed May 23, 2007 4:59 pm
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One Eyed Hopeful

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Just joined this forum group and although I don't have any stereo 3d setup as of today I am very keen to start. This is my first post.

I'm a complete newbie but have done a little searching across the web in the last 24hrs and found a couple of links related to the selection and building of DLP projectors to support 3d. Forgive me if you already have these links posted :roll: elsewhere on the forum sheets.

http://www.3d.curtin.edu.au/3dmovies/projectors.html

This link and the pdf links from it are useful for describing the general projector 3d sync issues testing and a useful description of the color imbalance problem between left and right eyes. I assume from reading this that it's better then to find a projector that has an even number of cycles at the sync rate (i.e 85Hz for the cheaper DLP market). does anyone know of a good projector in the sub US$2000 range?

next

http://www.tomshardware.com/2007/04/10/ ... page2.html

This link was great to just to show a complete projector system build that a newbie like me could follow and actually build easily from scratch, he even has a few game results

I think the projector approach is going to be best for me since it can be multi purpose to watch home theather movies and I don't have one already. The 22" LCD option from Iz3d would be nice but the price for that is at a premium compared to standard 22" LCD's.

Well then the big questions for me are which consumer price level projector should I buy and what nvidia video card should I buy? i don't like to hijack forum threads so just point me at another location if this is nott he place for that discussion.

p.s I love playing BF2 today in 2D is this one of the better performing 3D games or not, I was hoping the certification results are viewable soon!


Sun May 27, 2007 8:32 pm
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One Eyed Hopeful

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Thank you for posting this!

One question: The variable resister at timer 1 adjusts the delay. But why do we need a variable resister at timer 2?


Mon May 03, 2010 8:33 am
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Sharp Eyed Eagle!
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Answering a question from almost two years ago...

squarifying the output pulse:
The second variable resistor is for adjusting the pulse-width of the final output pulse so that it is equally high and low making it a square wave instead of a non-square pulse. You will need to tweak this every time you change vertical frequencies like 60 Hz, 70, 75, 85, 100, 120, and any others. The circuit components may need different numbers for 120 Hz.


Sat Mar 24, 2012 11:37 am
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One Eyed Hopeful

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There is a solution to the problem. 2 logic chip (SN7486N and SN7400) in the gap N555 . :lol:


Mon Mar 26, 2012 11:33 am
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One Eyed Hopeful

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iondrive wrote:
Answering a question from almost two years ago...

squarifying the output pulse:
The second variable resistor is for adjusting the pulse-width of the final output pulse so that it is equally high and low making it a square wave instead of a non-square pulse. You will need to tweak this every time you change vertical frequencies like 60 Hz, 70, 75, 85, 100, 120, and any others. The circuit components may need different numbers for 120 Hz.


There is a solution to the problem. 2 logic chip (SN7486N and SN7400) in the gap N555 . :lol: :lol: :lol: it is checked!


Thu Mar 29, 2012 8:54 am
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One Eyed Hopeful

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Nice find! When you say in the gap, what are you refering to? Could you be more specific please.


Also does anyone know of a HDMI version of this? I have a Projector that I am using with a Viewsonic VP3D1 3D converter. Unfortunately unlike the Optoma 3D-XL it does not have a vesa port for an emitter. I'd like to have the option to use IR or RF glasses in addition to or in place of the DLP Link glasses.

BTW the 3D-XL will not work with my Viewsonic PLED-W500 for whatever reason or I'd use it.


Thu Mar 29, 2012 5:04 pm
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One Eyed Hopeful

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OK! I will lay out the scheme in the evening.


Thu Mar 29, 2012 9:23 pm
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One Eyed Hopeful

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that's good!
the timer will be constantly stable! at any converting of a signal.I used this scheme in the project automatic cropping shtorka for the screen from VGA signals.


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Fri Mar 30, 2012 9:33 am
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One Eyed Hopeful

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Thanks for posting the schematic.

So is the sync signal in HDMI the same as in VGA? As in a pulse that can be tapped into using this method? Or is HDMI synched via some code that must be deciphered by the display, which is then converted to a synch signal?


Sat Mar 31, 2012 4:25 pm
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One Eyed Hopeful

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HDMI difficult signal. The personnel and impulses of a line are packed into packages.


Sat Mar 31, 2012 10:50 pm
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Sharp Eyed Eagle!
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hi sibboi and 3dnovice,

it's nice to see people are still interested in this. Too bad it's too out of date for most people. In some ways, the old analog signals were easier to work with compared to modern HDMI and other connections. Thanks for the skat sibboi. I'll take a look at it but for now I'll stick with the 555-only version but now that I'm building one of these I see that I need three 555 timers in order to do a better job since I want a phase shift that is just under 180 degrees. I should post some details when I'm done.

hahaha, I'm watching tv now and a character on the show I'm watching ("Psych") had a cat named "Chairman Meow". Hilarious.


Sat Mar 31, 2012 11:15 pm
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One Eyed Hopeful

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Hello, iondrive. It will be better to make on SN74LS74, and 74LS00 the phase shifter with provisions of 90,180,270 degrees.


Sun Apr 01, 2012 2:29 am
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One Eyed Hopeful

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Have you guys thought of using two DLP projectors in a stack and a dual output video card to split the 3D to the two units and a filter system to game with ?? you get no flicker at all, both eyes see 3D un-interupted. if you use 720p dlp units you can run at 60hz.. we talked some about it in other threads and over at AVS forum. ive been playing call of duty on my rig like this.


Tue May 01, 2012 3:18 pm
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Petrif-Eyed
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It's well known but dual projectors are another setup. I use dual projectors myself (silverscreen+linear pol) and haven't had too much luck with interference filters when i tried (too much light is killed, the hazzle of colorcorrection which in all makes the hotspotting and ghosting to be a minor issues). I believe the amount of success with interference filters depends on the colorspectrum of the projectors used. On the plus side i have to say that the ghosting was more or less entirely gone with the dolbyfilters.

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Last edited by Likay on Tue May 01, 2012 5:36 pm, edited 2 times in total.



Tue May 01, 2012 3:37 pm
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One Eyed Hopeful

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i agree that the dolby filters have major issues with color, polarizers can have ghosting and you need a silver screen. there is a better alternative to both, on ebay there is a filter kit called omega 3d, it is the same system as panavision 3d ( not well known ) it dose not need a silver screen and has very minimal issues with color if any and is higher in efficiency than linear polarizers. all the color correction needed with the dolby system reduces the output. not to just promote the system but mainly to show people there is a better alternative.
here is a video showing something about it

http://www.youtube.com/watch?v=10xwnUi5 ... ure=relmfu

not everyone will want to go to dual projectors but it is the best setup for bright no strain 3d


Tue May 01, 2012 4:01 pm
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Petrif-Eyed
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I had the impression that the omegafilters works exactly the same as the dolby and infitec system so they should practically suffer of the same kind of phenomenas (in the video the omegas looks very similar to the dolbyglasses). Do you know anyone who have such filters? (I could be wrong but i think Blackshark tries a setup with omegafilters but in that case i don't know about his impressions yet).
For now i have everything with 3d "hanging" because i don't like to degrade the experience for the stuffs available in the stores. Besides: Proper and futureproof softwaresupport is right now, least to say, pending for non-industrychosen "standards". I'm very curious of different technologies though. Are there any papers on the panavision system?

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Tue May 01, 2012 5:30 pm
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One Eyed Hopeful

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the omega filters are not like the dolby. other than they are optical filters on glass optics it is very different. here is a page i made about the system. mainly to explain how different projector spectrums effect the colors. dolby uses 6 bands, 3 rgb in one and 3 in the other. its an imbalanced color system. the omega ( that was branded panavision 3d but really made by omega ) splits the visible into 10 bands so 5 per eye making for even color and energy.

https://sites.google.com/site/passive3d ... inprolog20

here is a page with the same filter setup marketing under panavision

http://www.dpvotheatrical.com/Experience.html

you can actually buy the system unlike dolby/infitech, dolby dose not sell the projection filters to users like you and I, they are not the same as the eyewear filters.

its a long thread but here is a very detailed discussion with feedback on people who have it.

http://www.avsforum.com/avs-vb/showthread.php?t=1280393


Tue May 01, 2012 7:30 pm
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One Eyed Hopeful

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that AVS thread is long, if you look starting around page 45 youll see the discussion about this.

or here is some direct feedback of guys who set it up

http://www.avsforum.com/avs-vb/showthread.php?t=1407101


Tue May 01, 2012 7:39 pm
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Golden Eyed Wiseman! (or woman!)

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@ motorman45: do you work for Omega or are involved with their business in some way? Some of your comments on that forum strongly suggest that you are.


Tue May 01, 2012 8:27 pm
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One Eyed Hopeful

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Yes, but not only that i am the creator and engineer of the system, being an avid gamer starting in the 80's with 286 based pc's i am an avid tech nut. im glad the place i work for is offering it as a kit pretty affordable instead of only large cinemas being able to get this. i dont want to be a shameless promoter only get interested gaming and video fans be able to see far better 3d. dont take my word for it. you can see the user feedback, even the negaative in that forum. we did adress some issues with color for lcd type units and rectified any issues with those that bought ones made for dlp.


Tue May 01, 2012 8:37 pm
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One Eyed Hopeful

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didnt mean to hijack the thread.
im really interested in the ideas started here. ill leave dual passive setups to other threads.

so the idea of being able to alter the timing of the signal for refresh rates is one thing but what about adjusting the time on/off. i know there is a tradeoff with ghosting and flicker but the brightness levels are really effected by this.
ive seen that some shutter glasses work on a 25% open 75% closed or off time. modifying that would also reduce the sense of flicker too i would think ?
any thoughts..


Thu May 03, 2012 6:17 am
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Petrif-Eyed
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@motorman45: Thank you for the info. I spend way too little time on the avs forums. :oops:

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Sun May 06, 2012 1:40 pm
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One Eyed Hopeful

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As a fog - a question with points 3D VISION / it is necessary to know their schedule of switching.


Sun May 06, 2012 3:29 pm
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