In Part I of the How does 3D TV work? guide, we learned the basic correlation between the functions of the human eye, and the necessities of 3D TV. We learned that 3D TV must create a false sense of depth, and trick our vision into seeing 3D imagery. Now let’s take a further look into the facts behind how 3D TV works.

The reason 3D TV looks askew to the naked eye, is that it’s actually made up of two images. This is because the 3D TV is mimicking the human eye and producing two slightly different images, slightly offset.

To replicate this, try covering one eye at a time, you’ll notice that the world shifts slightly — this is because our pupils are several inches apart, allowing our brains to process information on a series of axis: or, depth and height. To scientists, this is known as parallax. To 3D TV manufacturers, this is known as 3D gold.

Active Shutter 3D TV

When shooting and editing 3D footage, everything must adhere to these simple rules. One image for the left eye. One image for the right eye. Now, fast-forward, to find dad sitting in his living room wearing a pair of active shutter glasses.

The clue is in the snazzy title: ‘active’ ‘shutter’ glasses contain active (powered) shutters. Working in conjunction with the 3D TVs inbuilt emitter — via infrared, Bluetooth or radio technology — the independent lenses in your active shutter glasses control which image your eye can see: one image tailored for the left eye; and one image tailored for the right.

Recap: Two slightly offset images plus one brain to merge the two. The result? 3D TV.

The running theme of dual images, coming together to create one 3D image remains throughout all of the 3D technology. The classic red and blue lens’ of the cheap paper glasses were no different (they acted as filters), and was the precursor to the polarised glasses you and your friends have been wearing in cinemas.

This technology isn’t defunct, it has merely been improved and superseded by far superior — and more expensive — technology. Active shutter technology is paving the way for the latest generation in 3D technology.

The technology in the active shutter glasses operates at a minimum of 120 Hz. If you don’t understand this, just understand that this is faster than your brain can decipher — creating a smooth, stereoscopic image.

Polarised 3D glasses?

Why can’t you use polarised glasses like you did in the cinema? Because cinema’s project not one, but two slightly different images from two separate projectors, onto a specially coated screen.

Thus creating the familiar image known as an anaglyph. The lenses in the so-called ‘passive glasses’ are designed to filter out one version of the polarised light image, while accepting the other.

In effect, one projector and unique set of light waves for the lens over the left eye; another set for the lens over the right eye.

Building a HDTV with this kind of technology simply isn’t commercially viable, because it’s extremely expensive and users would have to cover their screens with a special polarising screen. But take solace in the fact that the technology is out there, lurking on the horizon.

What do I need for 3D TV?

For the here and now, just concentrate on active shutter technology. This is what the major manufacturers are focusing on, and this is the area that will drive the technology further. For active shutter glasses to work, you need a few things:

• A 3D TV: The most noticeable difference between a 3D HDTV and a regular 2D HDTV is the emitter. This is the invisible link between your active glasses, and the 120 Hz pictures being fed to your screen.

• The correct set of active glasses: We’re already seeing a split in the camp with the technology of the glasses. Simply put, some manufacturers are using a technology known as E-D, while another is using ELSA. Guess what? They’re not compatible with each other, so a set of Sony active glasses can’t be used on a Panasonic 3D TV and vice versa.

• HDMI Cable: The HDMI cable connects your Blu-ray player or your cable box and allows it to pipe 3D content to the 3D TV, and onwards to your active shutter glasses.

So there you have it. The complete guide to how, and why 3D TV works. In summary; two slightly shifted images are created and received by your two eyes, where your one brain is tricked into misinterpreting the depth of field.

The technology in 3D TV works by creating a sequence of left/right images for your left and right eyes so fast it’s undetectable by the human eye. An emitter built into the 3D TV controls the technology in the active shutter glasses; activating and deactivating the two lenses in your glasses, therefore carefully constructing the illusion of 3D.

We’re gathering information every day about this emerging technology, if there’s a topic you’d like to see covered we’d be happy to hear from you.

Go back to Part One of our How 3D TV Works Guide.