How 3D Glasses Work 3D Glasses: How Do They Work? Now that 3D movies and television are becoming more common, you are probably curious how 3D glasses work. We will give you an easy overview here, which will help you decide which type of 3D technology might be right for you. How Our Eyes Do It To begin with, let’s consider how it is that humans can see in 3 dimensions. Since our two eyes are spaced a short distance apart, the images entering the left and right eye are of the same scene but from a slightly different angle. This is called ‘stereopsis’. In effect, the brain interprets these separate images by essentially triangulating, which produces the 3D we see. How 3D Glasses Do It Similarly, 3D glasses direct image sequences that were shot of the same scenes with cameras that are spaced a small distance apart, separately into the left and right eye. Our brain interprets this in the same way as it does the information coming into the left and right eyes in the real world through our eyes, thereby producing the illusion of 3 dimensions. There are 3 general types of 3D glasses, all of which accomplish stereopsis in slightly different ways. Anaglyph 3D Glasses The first kind of 3D glasses that were invented are called ‘anaglyph’ glasses. In the earliest days of 3D in movie theaters, for example, people were given anaglyph 3D glasses that had a blue lens for one eye and a red one for the other. The image sequences projected onto the movie screen were two slightly offset and overlapping angles of the same scenes, one sequence in a red tint and the other in a blue tint. In this way, each eye would only see the sequence from one camera, and stereopsis was achieved. This is the most primitive form of 3D for movies, and while it worked, the quality was fairly poor.
Passive Polarized 3D Glasses Modern movie theaters and many 3D televisions, on the other hand, use glasses with polarized, passive 3D lenses. This means that instead of the left and right lenses being different colors, they are polarized in opposite directions. Two projectors project image sequences on the screen at the same time, each polarized opposite the other. This means that when you are wearing your passive, polarized 3D glasses, your left eye only sees what one projector projects, and your right eye only sees what the other projector projects. So, once again, your brain interprets this as a 3 dimensional scene. Many modern TVs, such as the popular LG Infinia series, use this type of 3D glasses. Active Shutter 3D Glasses But not all 3DTVs use passive, polarized 3D technology. Many on the market now use what are called active shutter lenses. Sequences shot for this technology are still shot with two offset cameras at the same time, but at twice the speed. And when the moving sequences are played back, rather than overlapping, they alternate. This means that you have one frame from the left camera, then one from the right camera, back and forth throughout the entire program or movie. On top of the TV sits an emitter that tells a receiver on your active shutter glasses to open the shutter for the left eye when a frame from the left camera is up, and likewise for the right eye. This happens so quickly that you do not consciously perceive it, but again, your brain interprets this in 3D. Most 3D HDTVs on the market, such as the Panasonic Viera series, use this type of 3D glasses. Which Type Is Best? So now that you understand how 3D glasses work, you may wonder which type of 3D technology is best. Well, many people argue that the 3D illusion is better with active shutter lenses. Unfortunately, active shutter 3D glasses typically cost much more than passive, polarized ones do (though there no discernible difference in the cost of the TV sets). The good news is that many manufacturers include a certain number of pairs of glasses when you buy their set. In addition, most people who buy a passive, polarized technology 3DTV report being very happy with the quality of the 3D. The long and short of it is that both produce a startlingly effective 3D illusion. If you want to know about 3D HDTV or about some of the most popular 3D HDTVs on the market right now, please visit 3D HDTV Facts and select the device you want to know more about.