Personally, I blame Avatar and James Cameron for the explosion of 3D. Film critics seem to think it’s the beginning of the end (first cgi, and now 3D? We’re doomed!) I happen to think that 3D is mind numbingly awesome, but I’m also amused with cereal-box toys and bubble wrap. The truth of the matter is that the “new” 3D isn’t going away anytime soon. Love it or hate it, 3D is the wave of the future. For a 160-year-old technology, that’s pretty impressive.
We should start with some basics. If you already know how 3D works, you can skip the next paragraphs Though I might say something clever, but hey – it’s your loss. Viewing 3D requires the ability to calculate depth using two images, which is why we have two eyes. The visual cortex of your brain is performing on-the-fly geometry to figure out that your keyboard is close, but your monitor is further away, and that cup of tea you just made is so far out of reach you’re going to have to get up to get it. (Go ahead, I’ll wait here.) To simulate 3D, images need to display two slightly skewed views of the same scene to each eye. Roughly a quarter of the population can’t even see 3D effects because an eye doesn’t work right, or both eyes don’t focus in sync, or the image is interpreted incorrectly in the brain.
In 1853, Willhelm Rollman figured out how to simulate 3D using color-doped lenses to filter out images. You can blame him for those red and blue glasses. It wasn’t until the 1890’s that film caught on. William Friese-Greene patented a technique for viewing two separate movies projected on two separate screens at the same time. Greene’s method worked really well, but wasn’t practical since only one person could view the picture at a time. Plus it took James Cameron too long to make Avatar for 3D to catch on in the 1890’s. Cheap plastic made 3D possible in the 1950’s since movie theatres could hand out disposable red and blue glasses using Rollman’s technique developed a hundred years earlier. The down side was poor color, but since the world was only black-and-white in the 1950’s it didn’t matter.
Modern movie theatres use polarization (a method of filtering light) to display two images simultaneously. Those funky cheap sunglasses are attuned to each separate image (try putting them on upside down to give yourself a bad headache). The up side is that polarized 3D will display the correct color, but polarization causes a loss of brightness. Some 3D theatres (like Imax 3D) compensate by tweaking the brightness and polarization. And sometimes the projectionist is a doofus who forgets to remove the polarized lense and you end up watching a 2D movie that looks like somebody smeared engine oil over everything…
The human eye sees still images as motion with as few as 24 images a second. Anything below that, and it looks like the actors have toureetes syndrome. Our eyes actually see a continuous stream of light, so the more still images we see per second, the more natural it looks and the less headaches we get. When TV’s went digital, manufacturers had to invent new methods of producing each frame quickly. Early LCD and Plasma screens couldn’t re-draw the entire image fast enough, and ended up displaying part of the previous frame, which created a “ghost” image that became more apparent in scenes where something was moving across the screen. Advancements in technology have led to better screens which re-draw each frame faster, and the faster the frames are re-drawn, the smoother the image looks. For digital TV’s to look decent, the display should refresh at 60Hz at a minimum (that’s roughly 60 still-images a second, though it gets more complicated than that). Try turning down the refresh on your PC monitor and see how fast you get a headache. You could turn it into a drinking game! Just don’t send me the cleaning bill when you puke on the floor.
Fast-refresh TV’s make 3D at home possible. Since we need to see two images, the TV has to have a way to show each separate image fast enough that we won’t notice. At 120hz, TV’s can display two images at 60hz each, resulting in theoretical smooth viewing. This means that any TV running at 120hz is capable of 3D, but doesn’t have to use it. And no, 3D TV’s aren’t 3D all the time – you still need to have a 3D signal with two distinct images per frame. Even with a fast refresh, we need a way to filter each image so its only viewed by one eye at a time. Polarization like they use in theatres requires an expensive coating on the display that increases the price by $1,000 or more. Manufacturers have been experimenting with shuttering which turns out to be cheaper for the TV, but more expensive for the glasses. With shuttering, the glasses flicker in sync with the TV as it re-draws each image, filtering out the opposite image for the shuttered eye. To shutter, the glasses require a power source to flicker the crystal shutter and transmitter to stay in sync with the TV. Factor in the battery, transmitter, and liquid-crystal shutters, and suddenly you’re balancing the weight of a small European country on the bridge of your nose. Some displays, like the Nintendo 3DS and a few phones, use a smaller polarized screen to display both images, but it requires the viewer to be perfectly dead center. A correctly polarized screen can display two entirely separate images at once to two different viewers. On the plus side, I could finally catch up on Lost while my wife watches boring reality shows! On the down side, big polarized displays cost more than the annual budget of a small European country (give or take).
Faster refresh in displays means smoother images and a better picture, which is something all manufacturers are aiming for. As technology gets cheaper, all displays will be 120hz or greater, meaning a TV manufacturer can throw in 3D shuttering at nearly no cost and add a check-box to the feature list regardless of how much the consumer wants 3D. More TV’s will be 3D enabled or 3D ready, even if nobody uses them. Polarization will take a lot longer to improve before it becomes cheap enough for large displays, but it’s coming, like it or not. And as 3D capable TV’s reach a saturation point, movies and TV will start filming in 3D more often. We may finally get a chance to see just how big Adrien Brody’s nose really is!