Polarization means making light beams point in one direction only. Normally, like comes at us pointed in all different directions. A Polarizing filter only lets light from one direction through. They’re generally used in photography to avoid reflections – for instance, if you tried to take a photograph of a window, you wouldn’t really be able to see the other side as light would be bouncing off of it and into your lens. With a Polarizing filter, you’d cut that out, and be able to see whatever was on the other side of the window.
The unique and useful properties of a polarizing filter mean that by combining 2 filters, we can make a kind of dimmer switch for light. If you take two pieces of polarizing film (think back to junior high science classes now), and slowly rotate them around, at one point they will let most light through and at another point they will let zero light through. This is because in the first instance the direction of the light is aligned by the first filter than allowed to pass through by the next filter. However, when you rotate the second filter, you are slowly making it so that the aligned light is unable to pass through and reach your eye.
In terms of 3D tech though, being able to filter out particular light beams so they can or can’t be seen by each eye means we can deliver a unique image to each eye at the same time. How? We have two images at the TV side of things, and each one can be polarized in a different direction. We then add the same filter to a pair of lightweight glasses, and each eye will only see the light that is polarized in one particular direction.
This is basically the cheapest method of doing 3D, and it is far from perfect. It is used in large 3D cinemas where the quality of movie isn’t so important as the experience, and probably isn’t a full length movie – like at Disney World, for instance. The primary benefits are that the glasses are lightweight and incredibly cheap to produce, so it doesn’t really matter if people break them or ‘misplace’ them.
There are a number of cheaper 3DTVs being produced this year for the budget market, but I would suggest you stay away from them. You tend to get a lot of blurring between the images (so you can see both the left and right at once), and really need to be in a dark room to get the best of this kind of 3D. Dolby also have a proprietary system that apparently produces better quality than standard filters, and is currently used in a number of better 3D cinemas.
This is the best quality 3D you can get right now, and anyone who has harped on about how good Avatar was probably went to see it using this technology. Active LCD shutter means that the viewer must wear some pretty bulky glasses – each eye has a separate LCD screen inside it, as well as an infrared signal receiver that connects it to the movie being played. As opposed to passive polarization which just shows both images on screen at once, active shutter methods display one frame after the other, alternating between the views destined for the left and right eyes. The LCDs in the glasses then turn on and off in sync, blocking one eye out then the other. This flashes on and off so fast that your brain simply combines the two images and forgets the other 50% part where each eye couldn’t see anything.
The advantage of this method is that the quality is superb with almost no “bleeding” of one image into the other. Unfortunately, some people claim it gives them a headache. In all my years of playing games with active LCD shutter glasses from NVidia, I have never had a headache, so I suspect the problem is perhaps just something you get used to. When TV first came out, I suspect there were similar complaints from a large proportion of the population.
This will be the consumer 3D platform of choice for many years to come. Yes, the glasses are annoying, but then again we won’t be watching everything in 3D. When I sit down in front of my PC to play a game in 3D, for instance, I barely notice them. The latest incarnation of LCD shutter glasses from NVidia is actually quite light weight, wireless, and recharges from a small USB socket. The bulky models you get in high-end 3D cinemas are no longer bulky due to old technology, but simply to make them more resistant to wear and tear and discourage you from taking them home. If you are really against wearing glasses to view 3D content though – well, you’re going to be waiting a long time. Which brings us onto the 3rd method.
Parallax 3D displays show 3D content without the use of glasses. Though there are many competing technologies and there are rapidly evolving as we speak, the basic principle is that both images are shown on screen, then a filter of sorts bounces the images off in different directions. When viewed from a certain angle, you see the 3D effect. Most offer a variety of about 6 different angles you can view from, but outside of those you will lose the 3D effect and just see a blur of two images.
It’s a relatively new technology, and was shown first last year in the form of the words first consumer 3D camera by Fujifilm, which I had a chance to play with. The camera took 3D images, and was able to simultaneously preview and playback those images on it’s small 3D glasses-less screen on the back. This year, the Nintendo 3DS will be using a similar but somewhat refined version of the same tech to bring portable 3D gaming to masses.