| Author | Message | ||
     Alexander Oest Rating: |
I thought it would be a good idea to have a thread dedicated to the search for a DLP projector that'll do native 120 Hz stereo. There has been some discussion in various threads, and it seems to me that issues of colour wheel speed (or number of colour wheel segmens) and bypassing the internal frame rate converter (or buffer) of the projectors are the main issues. For starters, I dediced to do some searching on the topic. There's no conclusion yet, but in case anyone is interested, here is what I came up with. Acutally, there is a recent discussion of projectors and shutterglasses at avsforum.com: "DLP is most certainly fast enough for 3D applications. But it's not as clear-cut as it is with CRT. And the refresh rate may be a little low -- since DLP's generally do not do 120 Hz refresh."(1) I then went on to search for information on colour wheel rotation and refresh rates, and found these explanations: "Logically speaking, the wheel only has to make one rotation per frame. This way the projector will just have completed one rotation when the RGB and W segments have passed the light path and it is time to display the next frame. The actual active time for each color on the other hand will decrease with the number of segments on the wheel, just as Eric points out. For reasons of image quality, the wheel may rotate faster, but it strictly does not have to. A 60 Hz refresh rate would then lead to a minimum of 3600 RPM which is a much more real world number." (2) Trying to identify a projector model that was a candidate, I found this: "The Plus Piano isn't much bigger than the V-1080 and it uses a RGBRGB 120rps colorwheel."(3) and: "I read from one link off of some other post here that the new Plus projector soon to be released in Japan (called "Piano" or something like that? DLP 848x600 600 lumen machine) has a 4x color rate. According to the brochure, it has a 3 segment color wheel that spins at 4 times the "normal" speed. I assume this means 12 color segments per cycle, correct?" (4) Sounded promising, so I went on to the manufacturers homepage, where a press release said: "Four-times, six-segment RGB sequential illumination is also provided through the use of TI's new DLP Widescreen (480P) Component Set, which features support for a 240 Hz color scan rate. By featuring higher-speed (240 Hz) color wheel operation, the new HE-3100 is able to minimize color separation artifacts. As a result, longer movies will be much easier on the viewer's eyes."(5) Still sounded promising, but looking at the actual specs of the projector, I found that: "Refresh: Vertical :50 - 85 Hz" (6) 85 Hz is quite disappointing. And I can't even be certain that the 85 Hz isn't without the frame rate converter (which I assume the projector has). But I'll email the Danish distributor and ask if there's a chance of bypassing the frame rate converter. At least, it seems this projector has the capability in terms of colour wheel speed. The quest continues. Alex References: (1): http://www.avsforum.com/avs-vb/showthread.php?s=aa1b053a64f73f9f5d2e58a3d0530b1a&threadid=107396&highlight=120hz (2): http://www.avsforum.com/avs-vb/showthread.php?s=aa1b053a64f73f9f5d2e58a3d0530b1a&threadid=70025&goto=nextoldest (3): http://www.avsforum.com/avs-vb/showthread.php?s=aa1b053a64f73f9f5d2e58a3d0530b1a&threadid=111332&highlight=120hz (4): http://www.avsforum.com/avs-vb/showthread.php?s=aa1b053a64f73f9f5d2e58a3d0530b1a&threadid=20283&highlight=wheel+segments+refresh+rate (5): http://www.plushometheater.com/en/pr_oct_29.htm (6): http://www.plushometheater.com/en/spec/index.htm | ||
| Anonymous Rating: N/A |
Barco Galaxy is what you are looking for, if you have a fat wallet: http://www.barco.com/projection_systems/products/product.asp?element=928 http://www.barco.com/projection_systems/downloads/Barco%20Galaxy.pdf 110Hz is not the original 120Hz they aimed for, but is good enough. Guessing that prices range from 20000-100000 US$ depending on the optional extras, guestimating 50k for active stereo with no other addons. Check with your local Barco retailers. | ||
| Alexander Oest Rating: N/A |
Impressive projector! But with these astronomical prices, the joy of finding a $/€ 3-4000 projector basically doing the same would be even greater. I'll keep looking. Alex | ||
| Anonymous Rating: N/A |
Bring you GF2Go based laptop to a major DLP vendor and start testing! | ||
| Ryan Rating: N/A |
Just curious, why not use a CRT? | ||
| Anonymous Rating: N/A |
CRT works straigt out of the box, but is expensive, heavy, big, very low brightness, requires continous tuning (not as easy as you think) and a shitload of other problems. A tehnology by and for yesterday that is slowly fading away. | ||
| FrancoT Rating: N/A |
Hi all, anyone has tried active stereo using the projector NEC 150Z? It's a DLP projector with the new DMD (Digital Micromirror Device) tecnology. It basically means that it should be able to reach true 120Hz of refresh. Stereographics is claiming that this tecnology works on the Christie Digital Systems Mirage projector series, so it might work also on the much cheaper NEC. What do you think? Franco | ||
| Giorgio Bogoni Rating: N/A |
I think the Christie projector uses modified electronics (expecially buffers). I don't expect a standard DLP projector to be used for active stereo. Of course I may be wrong ... | ||
| M.H. Rating: N/A |
The Christie Digital Mirage series projectors are specificaly modified (I am working on stereo-video playback software for them). They use very fast refresh + in adition exactly one frame delay of internal buffer proceing. The exact 1 frame dealy of image procesing makes stereoscopic sync. to source data possible (you stereo HW is synced. to wrong data but the exact shif compensate this). According quality - the Mirage projectors beats enything existing in this area (including CRT). Some low end DLP in 3000 USD price range could correctly sync. to 60Hz source (30 Hz per eye) but it is to much flickering. I hope somebody will put some low end stereoscopic DLP on the market - it is just only an question for better speed and optimalized buffer architecture. | ||
| Alexander Oest Rating: N/A |
Update on the projector quest: Nothing so far... I haven't identified any low-end DLP projectors that deliver 100 or 120 Hz native. I contacted Texas Instruments (those who make the DLP chips) and asked for usable projectors. They suggested Optoma H50 and Dreamvision. I contacted Optoma in the UK, who said that their specs were native, and that the EP755 should work. I then called the Danish reseller, who'll lend me an EP755 to experiment with... though he was sceptical as to whether it'd work for my purposes, regardless of the UK branch's statement. He'll also let me try a 3-chip SIM2 home cinema projector, just for the fun of it. It's priced at around 10.000 US$ or €, so it's outside my range, but still, it would be fun if it did the same job as the much more expensive Barco and Christie projectors. Come monday, I'll know more. I also asked about native refresh rates at the AVSforum - see the thread at: http://www.avsforum.com/avs-vb/showthread.php?s=28cf3c0d8416e2b36f387500c4f9b2fb&threadid=165406&highlight=shutter The concensus seemed to be that all DLP projectors used conversion to 60 Hz - regardless of colour wheel speed and number of colour segments. Not particularly encouraging but not enough to make me stop looking ;-) I'll be back with an update when I've tried the Optoma projector. Alex | ||
| Ray Price Rating: N/A |
I have an LT150Z and have tried it, even though it claims to have 120Hz refresh it doesn't work. I think again it is foiled by the color wheel. | ||
| Anonymous Rating: N/A |
How about going the other way around? Instead of asking for something that doesn't exist, we can ask around for them to build in support for native 100+ Hz to display stereo. New DLP's pop out every week and the industry is getting very competitive, I'm sure at least someone would consider it and if it doesn't cost too much, maybe a little R&D, but not much harder/expensive to manufacture it could happen. Or is this something for Texas Instr to build into the the stuff they sell to the many projector mfgs? Barco showed that it can be done at high quality, high brightness and high price. Maybe someone else can do it with lower quality/brightness/price? Barco has no intrest in low-end hw, so they wouldn't consider this for many years to come, cashing in on their million-dollar systems. | ||
| ItsikW Rating: N/A |
Alexander, You may want to take a look on my recent posts in "Solution for DLP stereo projection". Is there a way to combine these two discussions? This is an important subject, and it should be contained in one discussion. Itsik | ||
| Anonymous Rating: N/A |
I thing that for the projector manufacturing company is esential answer of following questions: "Will we get back the money invested in the development" ? The economy play the rule, not the technology. Both Barco and Christie Digital demonstrated that it is technologicaly possible ... How much wolud you like to pay in addition to nromal projectro price to get the 3D effect ? + 20% ? + 30 % ? How big is the market for such product ? Is there enougt support according software, movie content, source signal HW ? | ||
| Anonymous Rating: N/A |
Well it's not just for stereo. A full-blown stereo capable projector would be expensive, the Barco/Christie contain a lot of special hardware that cannot be included in a small cheap DLP because of high R&D and mfg costs. But raising the refresh rate shouldn't be that hard, and can also be sold as "best in class image quality" "fastest refresh ever for best motion quality" bla bla bla. A small DLP proj for stereo only could never pay-back the R&D costs, but riding piggy-back on image quality, smooth-motion and so on would work. We just need to write down some nice little text and start asking around. There are many projectors that support up to 120Hz input and colorwheels spinning fast enough, now it's a question of the internal processing, but what the hell do I know, for me it's a magic black box, have no idea what happens inside. Can anyone get some DLP projector engineer into this discussion? | ||
| Alexander Oest Rating: N/A |
ItsikW, The other thread contains much discussion on dual-projector setups (and actually started with a suggestion for an alternative shuttering method of the glasses). This thread is intended to focus on the native refresh of DLP projectors in order to use *one* projector ...so I'm afraid I must disagree on the usefulness of joining the threads. Anonymous(es?), It might be worth pursuing the idea of getting manufacturers to make suitable projectors. However, I'm afraid that they don't see much incentive in stereo projection - even if they can advertise with superior image quality due to a higher native refresh rate. I might be too sceptical, though. I once emailed Davis (back when they were in business) about the refresh rate issue and got an email back which had circulated in their tech support and had been replied to and forwarded internally a couple of times. One of the employees suggested another that it might be worth developing a stereo-capable projector. I didn't see the internal reply, but emailed them and confirmed that that'd be a very good idea. I don't remember if I ever got a reply to that one, but if I did, it was probably one saying that "at present they had no plans of that sort". Still, my hope is that the projector we're looking for *is* out there, we just haven't found it yet. But meanwhile, it can never hurt to drop the manufacturers an email or two. Alex | ||
| ItsikW Rating: N/A |
Anonymous, Alex, I am afraid that your quest is hopeless, at least in the near future. The refresh rate of a single panel DLP projector is limited by the data throughput capability of the DMD chip, not the revolution speed of the color wheel. The maximal refresh rate is derived from the response time of a single DMD mirror, which is approximately one microsecond. This is just enough for 60Hz/24bit rate signal. Breaking this barrier does not mean faster electronics or faster color wheel; it means a brand new DMD chip. This is a multi-million dollar investment. Presently, it seems that the stereo market does not justify this. ItsikW | ||
| Anonymous Rating: N/A |
ItsikW, does this mean that it's up to Texas Instruments only? The makers of the DMD chips? If that is the case, then there is one company to focus at... What DMD chips are the Barco/Christie 3-panel DLP's using? Again, it's not just the stereo market that could use a higher refresh. The higher refresh, the more stable the image is and fast motion is displayed more accurately. | ||
| Anonymous Rating: N/A |
O.K. Let start the discuission from a bit different point ... Start thinking in the terms "it is not a technological problem, it is pure economical problem". Colud you expres your opinion about how much would you pay for what stereoscopic futures in the projector ? How much would you like to pay e.g. for a 1000 ANSI projector working in 100 Hz stereo ? How much would you like to pay for one suporting in addition polarized passive stereo ? | ||
| ItsikW Rating: N/A |
Anonymous, You are perfectly right: only TI can increase the data throughput rate of the DMD chip. I cannot tell what chips are used by Christie. But, I am pretty sure that these are standard chips, of the same type that are used in regular DLP projectors. The list of TI's DMD models and their roadmaps are not in the public domain. I had access to this until about a year ago, and to my best knowledge TI policy on this issue was not changed. Note that my comment was regarding a single chip DLP projector. It is possible to share the data stream between two or more chips to achieve a 120Hz projector. One approach is the three chip Christie's Mirage. Another approach wil be to use my two-chip Rate Doubler. I am very skeptical regarding your comment on market demand for higher refresh rate. You are probably aware that the projection business is extremely competitive. I am afraid that the refresh rate is considered to be a very low priority parameter (most people seem to be happy with 60Hz), so do not expect any improvements in the near future. I am not the right person to ask about economics, as I am a developer (most probably like yourself). I am also seeking market data of this type. Maybe we should open a discussion on the stereo projection market. This could help a lot of us. ItsikW | ||
| Anonymous Rating: N/A |
Economic POV: Both Barco&Christie manage to sell their million dollar setups, so I guess cheaper setups would sell even more and could be used for other stuff than hardcore military sims with unlimited budgets. As for a cheap DLP, I think up to 50% more than a normal DLP should work, since a 100% increase is the same as polarized setup (which also requires special expensive screen). A number I think many video-philes would pay for better image quality from a higher refresh rate (when marketed good). Yes it's a competetive market, but that also means that every technical aspect possible is fully exploited by niche brand mfgs, like home cinema DLP's that are very different than office type PowerPoint optimized DLP. I visited a audio/video-phile trade fair recently (the kind showing insanely expensive audio & video equipment for a small market users with extreme requirements in quality) and saw a lot of smaller brands showing rather cool DLP's used for home cinema projection. They cost a bit more than the PowerPoint DLP's but are a lot better for DVDs considering the base technology is the same. I still think that the only way a low-cost stereo capable DLP could ever reach the market is to use the same hardware/platform as for example a quality videophile DLP buying it for the image quality, the stereo market alone is too small. Think of it as 100/120Hz TVs, they are available in all stores selling TVs and are rightfully considered a lot better than their standard 50/60Hz counterparts. Yes, most TVs sold are 50/60Hz but the TV market was equally competive when the 100/120Hz came out and there was and is room for them. If anyone comes with a comment that 60Hz is enough, just go visit a TV store with side-by-side comparison of 60/120Hz, it's a HUGE difference, or set a VGA screen is 60HZ then 120Hz, rock solid!!! (though TV/VGA and DLP comparisons are like banana and apple comparisons it's the only kind we can make now) Market data, get some numbers from some of the more expensive DLP for home cinema, it's a niche market like stereo projection, should be good enough data to be used in the stereo world. Am I the only one thinking that the only way to battle this is to join forces with another small market for higher refresh rates? | ||
| ItsikW Rating: N/A |
Anonymous, No question your strategy is good. It is true that for high quality home cinema high refresh rate will be an asset. However, even in this niche, I am not sure that this is the highest priority item. Think for example of lamp lifetime, color quality, contrast, uniformity, etc. As I said above, with the present DMD technology refresh rates higher than 60Hz can be achieved only with two or more chips working in parallel. The least expensive approach is my Rate Doubler idea, which will allow to combine two standard Power Point projectors to get a real 120Hz DLP projection system. If a home cinema DLP projector costs 25% more than a Power Point projector, than two Power Point projectors will cost 60% more than a home cinema DLP projector. Itsik | ||
| Alexander Oest Rating: N/A |
ItsikW you write: "This is just enough for 60Hz/24bit rate signal"... but how about 16 bit colour? There must be a trade-off between colour depth and refresh rate, so accepting fewer colours must allow for higher refresh rates. Alex | ||
| ItsikW Rating: N/A |
Alex, In principle, it should be possible to drive a single DMD with a 90Hz/16bit rate signal, so I believe you are right. However, this does not fit nicely in the present DLP hardware, so such conversion may require substantial re-engineering. The question is who will buy this compromise. It is much easier to implement a 120Hz/12bit conversion, which is essentially what the Rate Doubler does. Then with two projectors one can obtain full 120Hz/24bit stream, and no compromise is done. Itsik | ||
| Anonymous Rating: N/A |
Itsik, where do you live? Somewhere here: http://www.venturecup.org maybe? Because that is a free opportunity to turn an idea into a solid project with pro help to get the paperwork done to look for some funding. | ||
| ItsikW Rating: N/A |
Anonymous, Thanks for the advice, but I live in Israel Itsik | ||
| Alexander Oest Rating: N/A |
A follow-up: The Optoma EP755 doesn't work with shutter glasses. I tried it out, and had the exact same problem as richardw describes in the thread: http://www.stereo3d.com/discus/messages/21/1206.html?1033334703 There were no options in the menu of setting the projector to native refresh. I guess the recommendation I got from Texas Instruments and Optoma UK were just sales talk, not qualified information. Didn't try the SIM2 projector, but it turns out that it's not a 3 chip projector, but uses a colour wheel. I think it won't work either. Alex | ||
| Arnim Sauerbier Rating: N/A |
The explosion of computer gaming should create a market for 3d projectors. I've wanted it for over a decade ;) My idea was to stack two cheap projectors that can do 60hz, put polarising filters, 90 degrees offset, in front of each. Aim them carefully so the images overlap. Then multiple people would watch with passive polarizing glasses. cheers | ||
| M.H. Rating: N/A |
Arnim: Your idea is in praxis used for at least 1 year by several companies. Unfortunately to buy 2 even cheap projectors is not price accptable for a lot ot people now ... Another problem is to get signal for this 2 projectors. Automatic image redirection works O.K. on dual output graphic cards for OpenGl stereoscopic application ... No generic wapers doing this for games exit if I know O.K. now ... Maybe VrCaddy + Winx3D ? Did anybody test this ? | ||
| Alexander Oest Rating: N/A |
Arnim, I think stacking two projectors with polarizers is the way to go. Especially as projector prices are falling, and no DLP projectors in the lower price range is able to display a picture sufficiently fast for shutter glasses. The big problem is getting the signal to the two projectors. Stand-alone splitters are too expensive. Dual VGA graphics cards might be able to output 3d games on seperate ports, but I don't think a stable solution has been found yet. A year or so ago, this was discussed intensively in this forum, but postings about this topic are less frequent today. Alex | ||
| Alexander Oest Rating: N/A |
Hi Michal You beat me to it ;-) But, regarding the dual output thing, did anyone succeed in getting a stable dual VGA output the way that Ray Price recommends in an earlier discussion? Alex The thread mentioned can be found at: http://www.stereo3d.com/discus/messages/24/1164.html? | ||
| Maart Rating: N/A |
Yes I did, it works pritty stable in direct3d near perfect in StereoOpenGL. btw, video splitters are cheap. with a scan converter you could build a vga to 2 svideo ouptut 3d signal splitter for about 1000 euro i've build a wooden projection case that rear projects the signal on a 2x1,5 meter screen. I tell you: Max payne never looked so good! Maart | ||
| Alexander Oest Rating: N/A |
Maart, Pretty stable is good enough for me! Would you say that the quest for a suitable method is over, then? Do you use the dual VGA setup regularly? What's that about a projection case? Something like the do-it-yourself TV set based projector with a fresnel lens? Any pictures? Alex | ||
| Maart Rating: N/A |
About the unstableness, sometimes the left and right signal getting reversed for a frame or so. This is due to an irq conflickt I guess. It seems that when the cd-rom loads this happens for instance. emulating the cdrom from harddisk helps a lot. but i think there is another little conflict because it sometimes still happens. it's ot realy bad but i would like to get rid of it. About the case, it's not realy do it yourself. there went quite some time in the develpoment of it. but it works great. because of the rear projection the image still looks quite bright (projectors are 2x1000 ansi lumen) with lights on around the system is no problem. Yeah i got pictures. I will scan them in at my mothers home at x-mas. | ||
| juj71 Rating: N/A |
How well did the dual projector set up work? I'm looking at picking up 2 Plus dlp's (2000 lumens) but need to be able to test them in the store before I buy. Any Ideas? Thanks Scott | ||
| Alexander Oest Rating: N/A |
Maart, How about those pictures, we were talking about? I'd really like to see your system. Alex Looking at the preview page, I can see the above message looks a bit naughty... I'm talking about your projection system - and I'm about to leave home in five minutes so I don't have time to rephrase it properly. | ||
| Anonymous Rating: N/A |
I've been told Christie sells a DLP projector working @ 104 Hz with shutterglasses without the color wheel for about 60.000 euros. Can we call it a DLP projector or not? | ||
| Maart Rating: N/A |
Hi Alex, here is a picture of my system (and me with it), I've edited the picture so there is the idea of a 3d picture projected on it, otherwise it will look blurry anyway.  | ||
| Maart Rating: N/A |
Hi Alex, here is a picture of my system (and me with it), I've edited the picture so there is the idea of a 3d picture projected on it, otherwise it will look blurry anyway.  and here is an artistic impression of the setup that I'm building  I hope you all like it Maart | ||
| Alexander Oest Rating: N/A |
Looks impressive. Any chance to see what's inside the case? Have you considered making a web page describing the development of your projection case? Seems it could deserve it. Alex | ||
| maart Rating: N/A |
sorry, no look inside. webpage is at www.visionair3d.com | ||
| Anonymous Rating: N/A |
Wonderful web site, was very useful. Lovely touch having this guestbook. Thanks | ||
| Anonymous Rating: N/A |
Great stuff here guys, check this site out! |
