DIY polarizer glasses

[raviori]

It's my understanding that the passive (and active) 3d glasses use circular polarizers to avoid losing the effect when tilting the head, but the polarizers for each eye are still angled a specific way?

Also, where should one source a polarizer film to make passive 3d glasses?

eBay lists only camera polarizers in the results. I just need a film I could cut to a very big glasses stencil.

Reason for DIY is experimenting with CAVE setups and custom very high fov coverage for glasses.

 

PS. No this has nothing to do with my other topic about an AAXA pico projector, that's too dim for a CAVE setup.

[gyro_gearloose]

My understanding of the use of circular polarizers in 3d glasses is that one eye has the light polarized clockwise, and the other is polarized counter-clockwise. Lee filters sell circular polarizing filters, but they aren't cheap and I don't think they sell the filter by the sheet like they do with conventional gels. You might be better off staring with some sets of these glasses. They're designed to fit over normal glasses so they might be big enough for your needs.

[raviori]

I was thinking more along the lines of a ski mask visor.

 

Un unrelated question, is silver projection screen for passive 3d a recommendation or requirement? Why?

[musht]

I was thinking more along the lines of a ski mask visor.

 

Un unrelated question, is silver projection screen for passive 3d a recommendation or requirement? Why?

 

Think polarisers need to be pretty much in line with optical path, ski mask style would put path betwixt projection and eye into distortion.

 

VR goggles depending on number of viewers might be more ,cost, effective.

 

Isn`t silver projection screen just the highest gain finish?

[ImagineerTom]

For front projection silver screen is essential for linear polorization based 3D; bouncing off any other type of screen the orientation is lost and there’s epic ghosting.

 

For circular polarisation, rear projection or shutter glasses based systems then silver screen helps but isn’t essential.

[Karel Bata]

Active 3D does not use polarisation. The L and R glasses switch on/off alternately. The projected image is sequential L and R (actually they use triple-flash to reduce sync problems - too complex for here. google it).

 

If you want to use any kind of polarisation a silver screen is essential. You may get some results without, but you will also get crosstalk which will compromise the viewer experience and your 3D.

You can now buy the screen as a sort of paint. But don't go near this unless you employ someone who really knows what they're doing!

 

For filters got to 3DImages http://www.3dimages.co.uk/ Dave Burder there is excellent for advice. If you put 3D glasses over a projector lens they'll likely melt. The glasses are also manufactured to lower optical tolerances than proper filters.

 

Another possible route is linear polarisation, such as used in Imax, and by many for their home projectors. I've used it for rear projection, but needed a suitable screen. Imax cinemas throw their glasses away, so I don't know what scale you're working on but you may (I did) be able to talk the ushers into letting you take away a huge pile after a screening and use those. Good source for tests. Be aware that with all such filters the tilt is important - it must be at right angles to the axis of projection. Too often I've seen filters leant against the projector with consequent crosstalk. An easy mistake too if the projector is tilted at an angle - the filter angle must match.

 

BTW linear are polarised at 45 degrees to their square shape, corner to corner. Took me ages once to figure that out!

 

Cheapest place for glasses is eBay from China. Expect several weeks delay. Buy cardboard.

 

Have you considered anaglyph? No polarisation required, but your color pallet would have to exclude bright reds, blues, and cyan.

 

Best of luck. Get in touch if you want more advice.

[Karel Bata]

EDIT Just realised: 'triple flash' is used in cinemas. I don't believe it's in use with domestic projectors as it requires 144fps. So with simple L/R at 24fps you will get depth errors with fast moving objects moving along the x axis.