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Thread: why no "polarizer wheel" similar to color wheel in video projectors?

  1. #1
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    Default why no "polarizer wheel" similar to color wheel in video projectors?

    I just got into stereoscopic 3d with projectors and there seem to be two ways to do it: active 3d glasses and 1 projector projecting at 120 Hz, 60 per eye and the glasses blocking one eye at a time, or using 2 projectors overlaying each other displaying at 60 Hz with polarizer filters attached to the lenses and then passive glasses with polarizers as well. What I don't get is why isn't passive glasses and a single 120 Hz projector option thing? I don't see what's hard in building a mechanism that rotates polarizers into and out of the beam path so what's the problem here?

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    There's also a technology that uses narrow band filters and different rgb for each eye. The really simple answer to projectors for stereo (please 3D is something else entirely) boarding two by two is you throw away so much with any of these techniques that the simplest way to fill a large screen with enough photons is to use more projectors.
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

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    Quote Originally Posted by laserist
    There's also a technology that uses narrow band filters and different rgb for each eye.
    Please tell me more, never heard of this. Are there any released projectors or projector addons and glasses that have used this technique? If it results in glasses which are less dim it sounds like a superior technique. I understand your point, but projector brightness vs cost has been improving greatly, what is the point of using 2x the optical engines, PCBs, enclosures and aligning them if you can use one bright one? And if brightness was the main reason for dual projector setup, why are there active stetereo/shutter glasses + 120Hz projectors but not passive glasses + polarized 120Hz projectors? The first decreases brightness too with 50% of the time not displaying anything for each eye and the polarizers causing dimness on the LCD panels used on the glassses. Is the brightness in your opinion the only thing preventing a "polarizer wheel" based video projector in conjunction with passive glasses from becoming a thing.

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    You really have to do your own research. Really bright projectors are way more than twice as costly as ordinary units. Scalability is important when you're talking about large venues. It's actually hard to make a good argument that stereo is more than a once every generation gimmick.
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

  5. #5
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    If I knew what I had to search and found what you mentioned myself I wouldn't be asking it here instead. "Scalability is important when you're talking about large venues." Who's talking about scalability or large venues? Gimmick or not I want to talk about the technology in an online board, I hope not everything I post here has to have some business purpose...

  6. #6
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    Instead of a rotating polarizing filter wheel, a large aperture liquid crystal cell is used to quickly switch the polarization from horizontal to vertical. With my previous employer, I made electrically switchable hologram optical elements to do the same thing with faster switch times, better contrast, and hopefully cheaper. It wasn't going to be cheaper so didn't fly, but the contrast was huge (when used with a really good screen). And, since we were going from right-hand circular polarization to left-hand circular, the cheap passive glasses gave absolutely no ghost images when the head was tilted significantly. Also, the glasses could've had curved lenses.

  7. #7
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    Here is a solution.
    wondering why it isn't the norm and included with the 3d ready DLP projectors instead of powered shutter glasses.


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    The real reason there isn't more development in 3D technology is that it failed in the marketplace. It's not worth the time (and money) to add this to TVs and video projectors because the end user doesn't see it as a valuable add-on. 5 years ago it was the next big thing. Now? Not so much.

    Adam

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    Quote Originally Posted by buffo View Post
    The real reason there isn't more development in 3D technology is that it failed in the marketplace. It's not worth the time (and money) to add this to TVs and video projectors because the end user doesn't see it as a valuable add-on. 5 years ago it was the next big thing. Now? Not so much.

    Adam
    I think the technology is still evolving and developing but yes, in the home, it failed. Eager home users were after that 3d experience they had in the theater. The problem was, an immersive 80'~100' theater screen vs 42"~70" home screen. Hardly immersive when it feels like you're looking out of your living room window. Interest dropped off considerably. The next big thing will be VR but it will need to be true immersion and not just a headset. We're a long way off but we will get there...

  10. #10
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    Cool technology only leads to a cool experience after a whole lot of creativity, experimentation, hard work, and learning from mistakes. Most of the immersive experiences I've seen to date skipped the creativity step, jumped right into experimentation with some process that would allow the hard work to be avoided, and are empirical proof of Sturgeon's Law...
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

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