When I went to see Avatar over the weekend, we were given different 3d glasses to the ones we’ve had before. They weren’t the usual passive polarized glasses, and they didn’t look like the active glasses you get for home cinema.
The glasses had pretty reflective lenses, and looked more like mirror shades. Also, when the cinema wasn’t showing a 3D movie, the right hand lens went completely opaque
How do they work?
In: 4
They use dichroic filters, which are extremely accurate color filters. They pass along slightly different shades of red, green and blue for each eye, while blocking the very similar but slightly different shades of red, green and blue meant for the other eye.
When showing 2D films, only the “default” shades of red, green and blue are used, which all go into the left eye.
Edit: I found that if I wanted to see the difference, the easiest was to look at a red object in a movie, and alternately closing one eye or the other. The red would be slightly more orange on one side. It’s so subtle that we normally don’t notice it when looking with both eyes.
There are many different types of 3D glasses for 3D movies.
There are systems that simply use two colored lenses, this works for projection in the cinema, TVs and printed stuff but doesn’t look very nice due to the colors.
There are active systems wit shutters that will alternately blind you left and right eyes in tandem with a monitor, they are expensive and mostly work for things like gaming.
There is the classic 3D effect that was sued by Avatar when it first came out, that used polarized glasses. They work well for cinemas as long as you don’t tilt your head.
There are cheap version that consist just of one dark lens and a clear one (or a regular sunglasses with one lens poked out) that work for all types of moving pictures as along as the movement is of something rotating. (they take advantage of the fact that your eyes are stupid and don’t process dark images with the same speed as bright ones)
There are also stuff that are basically just two displays in front of your eyes as you see in VR applications.
One new tech that might be what you encountered uses glasses that use Interference filter instead of polarization.
There are also different types of cinema glasses using polarization that are incompatible with each other but use the same general idea with slight tweaks.
It essentially works by having two sets of slightly off projections or images being displayed over one another that have different 2d perspectives, the same as your eyes. One “lens” will filter one of those images/projections, while the other filters out the other image/projection. Your eyes will take in these two different images from each eye and your brain will process it into a perceived 3D image. This applies to both types of 3D glasses(polarized or colored).
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