The Art Of Seeing In 3D

Film making is almost as old as the entertainment industry itself, and while there have been major advances in the field, the biggest technological step that has been taken so far is in 3D technology.

Everybody has seen at least one 3D film, and had to contend with the thick-rimmed glasses that make everybody look like Roy Orbison. The technology slowly started making its way into our homes, with many 3D televisions now available for purchase. But one thing that users will immediately notice is that the glasses for the cinema and the ones used for home viewing are completely different. While the cinema glasses make you look like Orbison, the 3D television transforms the user into Robocop. They are big, bulky, and most importantly, they need a power source. Why are the glasses so different and how do they work?

Well, some user might know how 3D images are displayed to each eye, and that the brain thinks it’s seeing one image, where there in fact are two. For 3D televisions and monitors, the glasses shutter out images at an alternating pace, which is usually around 120 frames per second. Each eye in fact sees the same image from a different angle, but the brain is tricked into thinking it is one image – making it look 3D (more on this a bit later). But why don’t we use the shutter glasses when watching a movie in the cinema? The home glasses can run up to R1000 a pair, while the plastic glasses from the movie look like they cost about R5 each.

Although the principle is the same as the old red-and-blue passive glasses, the movie spectacles are called polarized glasses, although still passive. When looking at a screen without the glasses, users will see more than one set of images, one with a blue hue, while the other will look slightly red. The glasses use lenses that filter out light waves projected at certain angles, and each lens only allows light through that is polarized in a compatible way.

Each eye will only see one set of images on the screen, and together, the different sets of images trick the brain into “seeing” a 3D image. It would in fact be possible to use the polarized glasses in one’s home, but the polarization technique is very difficult – all possible methods would require the user to coat their screen with a special polarizing film first.

But the most common form of watching 3D on a television still is LCD glasses, and connects to any 3D-ready television screen using infrared and a stereoscopic sync signal connector, which gives it the name of Stereoscopic 3D.

As the 3D images are displayed on screen, the picture alternates between two sets of the same image. The two sets are counterbalanced from one another similar to the way they are in passive glasses, like the ones from the cinema. But the biggest difference is that the two sets aren’t shown at the same time, as they turn on and off at an incredible rate of speed (120 frames per second). In fact, if users were to look at the screen without wearing the glasses, it would appear as if there were two sets of images at the same time, making it look blurry.

Even if users have the necessary bits to view 3D content, it won’t bring Riaan Cruywagen into your living room for dinner. The content shown on the screen must be optimised for 3D first, but some modern 3D Blu-Ray players can actually upscale 2D films to 3D. So from the descriptions of each pair of glasses, it should become clear why cinema glasses won’t work on a home theatre system and vice versa. The home glasses use LCD lenses that electronically switch on and off, while the polarized glasses in a cinema only filter out certain light waves, creating the image.