| Author | Message | ||
     3dvideoProducer Rating: N/A |
what projector or projectors are available to display interlaced 3d video using polarized glasses suiteable for about 100 people??? Is there a single projector that can handle this or should two projectors be used??? thanks all! | ||
| Eric Lindstrom Rating: N/A |
two projectors of any type can be used if polarization filters are used. some specialized projectors have the ability to do this solo. To keep costs down, I would reccommend the use of two LCD projectors with polarizers. some models incorporate polarizers from the factory. a couple manufacturers specialize in stereoscopic projection systems. Polarized glasses themselves are relatively cheap, and are available from many sources. I would suggest looking into the links here at Stereo3d on the subject; they have many links and infos on the subject. just follow this link to http://www.stereo3d.com/projection.htm -Eric L. | ||
| Alexander Oest Rating: N/A |
Just bear in mind that some LCD projectors are pre-polarised. This will give you a black image if, say your projector is horisontally pre-polarised and you mount a vertically polarised filter in front of it. So try before you buy. Alex | ||
| Anonymous Rating: N/A |
to Alexander Oest and others, I have the same problem with a mitsubishi 3 LCD video projector(LVP-X400) which is pre-polarised, so how to polarise with 90° difference two projectors with the same light output inclination like this one ? I should inverse the polarisation of one projector but how ? thanks all!! | ||
| Giorgio Bogoni Rating: N/A |
Yes, all LCD projectors are pre-polarized but I tested my SONY VPL-CS1 and I noticed that at standard 45°/135° there's no pre-polarization (or, better, there's no unexpected effect placing in front of the projector a 45°/135° polarizing filter). So I expect 45°/135° polarizing filters should work on any LCD-projector ... but I may be wrong. | ||
| Alexander Oest Rating: N/A |
I'm not an expert in optics, but if a de-polarising filter exists, I suppose you could put it in front of the projectors (or maybe just one of them) and then put polarisers in front of the de-polarising filters. AFAIK the polarisation comes from the LCD panels in the projectors, so to change that, you'd have to turn the LCD panel itself - and thus turning the whole picture. To Giorgio: With your solution, doesn't you loose a lot of light? The light thrown on the screen is polarised by two filters at a 45 degrees angle. That should dim it a lot. Lots of supposing here! I've asked my good colleague who's a photographer, and he said he'd dig up a book on the topic. Hopefully, my guesses will be a bit more educated in the future ;-) Alex | ||
| Giorgio Bogoni Rating: N/A |
Yes, I loose a lot of light but even with a de-polarizing filter you loose a lot of light. It would be better to use a material that can rotate the polarization of light (I' m testing polypropilene right now: 90° rotation and a little de-polarization) | ||
| Eric Lindstrom Rating: N/A |
Giorgio, I was contemplating the possibility of construcing my own polarizer for a flat-panel LCD display. There was that one laptop which used opposing strips to polarise each horizontal line on the display, and you used polarizing glasses to view two interlaced images. Now, using VRCaddyMe, it is possible to interlace the output to the screen, but using line blanking is impossible. could this polarizatin technique be used to blank the lines using polarized filters, rather than a hardware based line-blanker/shutterglasses? I figure if I used a metal straight edge and matte-cutting knife (exacto blade) to cut thin strips of polarized film, and fix them to a glass plate on the display, this may work. then, two corresponding filters are placed in front of the eyes, allowing each eye to see only it's designated image. Just an idea I had for a HMD design. Do you think this is feasible? -Eric L. | ||
| Giorgio Bogoni Rating: N/A |
Eric, look at your LCd monitor wearing polarized glasses and close one eye, then the other. Light is already polarized. So you need to rotate polarization of 90° only of, let's say, even lines (of course you can also de-polarize all the lines an re-polarize alternatly in opposite directions witha loss of light and a lot of work ... we'll not follow this way!) I've tried a lot of transparent materials and I've found that polypropilene of 17/19 mm. of thikness rotates the polarization of light of 90°. (it also have a small de-polarization side effect but never mind!) Of course if you put one upon the other two sheets of 19 microns of polypropilene light turns to the previous polarization direction. Try looking at the LCD monitor with a sheet of polypropilene on half the monitor, wearing glasses and closing eyes you'll think this is the right way. You'll enjoy all software for interlaced stereo! I've tried to cut stripes .. impossible! We need to find an ink with this property that can be printed ... or something else ... Giorgio | ||
| Eric Lindstrom Rating: N/A |
Ah, I see what you mean. It seems like my idea needs some more work, Still, I may be able to figure out something. Thanks for the suggestions. I have a small amount of Polypropylene film from my graphic design days. I tried the trick you described on my Laptop's LCD, and I see what you mean. I don't know that cutting strips is an impossible task, but it will require spacial equipment. Perhaps not an ink, but using a solution of Propylene Glycol saturated with some sort of polymer would do the trick, painting the plastic directly onto the display with a technichal pen, and wait for the Propylene Glycol to evaporate. Either that idea, or maybe some manufacturer makes a Propylene film with an alternating thickness of 38-19 Microns down it's length (just cut it to fit the display? might work if it exists.) I'll check with some aquaintances into polymers or resins that exhibit the same properties as the Propylene, The only drawback would be the flaws created by using such a substsance (irregularites or air bubbles might mess up the polarization.) Either way, I'll keep looking for a solution. Thanks again! -Eric L. | ||
| Giorgio Bogoni Rating: N/A |
Eric, I've been looking a long time for a way to reduce the thikness of a 38-microns polipropylene film. No chemical way seems to be feasible, nor I aspect a CO2 laser to work. Maybe Opticite (polystirene) is easier to manipulate; I've found it works the same way. I appreciate your suggestion of the solution of Propylene Glycol but, first of all, we need to understand WAY these films rotate polarization of light. Maybe is due to the molecular composition or maybe to the production method. I think the first one because Polypropilene and Polysterene are produced using very different method. I'd like to work in this area, keep me informed. Giorgio. |
