Introduction to 3D Technology
Seems like whole world is talking about 3D this year, though half of them think 3D is dead before it even began, and the other half knows very well that 3D is simply the next step in the evolution of viewing digital video. In actual fact, much of the technology being touted as amazing new 3D has been around for around 20 years or more. Let’s take a look at the 3 main types of 3D display out there so you’ll know what they’re trying to sell you in the local electronics store next time you go to upgrade your TV.
First though, what on earth is 3D and why is it so important?
3D is how the average human sees the world around them – though you should know that not being able to perceive in 3D is actually quite a common disability among many adults. Assuming you do see the world around you in 3D though, how can you artificially produce and replay something in 3D, like a movie or video game?
Being able to see in 3D means that your vision has a sense of depth, of how far objects are from your eyes. Your brain automatically calculates this for you by combining the images it gets from your left and right eyes, and working out the tiny differences that occur when you look at something from a different angle. You can see what I mean by holding a finger in front of your eyes and looking forward. Close one eye, then open it and close the other. Do this quickly and you will see how different each one looks. Your finger is in a completely different place to each eye, but your brain recombines the two and figures out that it means your finger is close to you.
Making a 3D movie is as simple as using two video cameras, which are fixed together at roughly the same distance as the human eye. Each one takes a slightly different recording, which when played back to the human brain is able to show you not only the visual scene but also the depth of everything you see. If the movie was animated on a computer, making it into 3D is easy as it merely involves re-rendering all the movie data from a slightly different angle. If the movie is shot with 3D in mind from the start – as Avatar was – the effects are stunning.
3D games are actually incredibly easy to do, as all the data required to figure out where each object is in 3D space is held right on the computer and can be processed in real time. In fact, many of us were playing PC games in 3D as early as 10 years ago, and the technology is exactly as those in a lot of 3DTVs and cinemas today.
Assuming you have some 3D data, either a movie, computer generated animation, or video game – the problem is then how to show it to the viewer. This is the technology aspect we’re going to be discussing a little today.
Before I explain some of those though, let me say I won’t be talking about those tacky red/blue glasses you get with cheap old 3D DVDs and comics, as that isn’t true 3D and the quality is shockingly poor – quite apart from the fact that everything you see is then coloured red and blue!
All these 3D technologies essentially boil down to how to get that slightly different image to each separate eye – without the other eye seeing it too. Since regular TV’s show the same picture to both eyes no matter what you do, 3D is impossible on them. That’s why you absolutely have to get a new TV if you’re going to view any kind of 3D material.
But how can we deliver a unique image to each eye?
1. Passive Polarized Glasses:
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.
2. Active LCD Shutter Glasses:
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.
3. Parallax displays:
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.
My experience with Parallax displays has been less than impressive. Firstly, keeping your head in a fixed position is just annoying. Especially if you’re viewing something in 3D, your head has a natural tendency to move around and want to see it form different angles. Also, the depth you can perceive on one of these display is quite poor. It doesn’t really “pop out” at you at all, even if it does look somewhat like it is 3D. I have yet to see the 3DS though, so I won’t comment on that until it’s out. Either way, this kind of 3D will not be coming to huge 3DTVs anytime soon, or possibly at all.
I hope that gives you a little insight into all this new-fangled technology. Don’t forget to check out my other tech tutorials.