3D - 2

Why do we need TV's with 120hz to enable 3D?

Why don't we just create a new format where instead of creating two pictures and shifting them to make the 3D image just make one image that looks like two pictures but is just one. I just think this is a stunt to make more money. If we can use mp4 and wmv, why cant we do the same for 3d images in a similar fashion. We would still be using raw videos if it wasnt for mp4 and all the other formats. Why is it that we need 120hz for 3D?

Public Comments

1. it's messed up how they sell for more and more money the HZ for LCD's because LCD are apparently really flawed with motion blurring problems, When I bought a 60hz LCD I was so dissapointed when watching especially high def sports, it's Like WTF did I pay for, they should never sell something that has a flaw (blurring) like this, and then market TV's with a bit less blur but sell for thousands of dollars. I say a plasma is still the best way to go, but making sure you get a reputable one like sammy or panny.
2. I'm not sure that you understand how 3D (stereo viewing) works. You can't take a single image and shift it. You need to take two images from different angles, just like our two eyes see the world from two slightly different angles. Then you need to present the two images separately to each eye. This is usually done with glasses that act as shutters, allowing the left eye to see only the left image and the right eye to see only the right image. You generally need a refresh rate of at least 50 Hz (the US uses 60, Europe 50) to avoid seeing a flickering image. Because, with 3D, each eye is seeing a different image, you need to double that rate (120 Hz in the US) to avoid flicker. While 3D may well be a gimmick, there is a real requirement for higher refresh rates due to the flicker threshold.
3. First for 3d to work the left eye can not see the right eye image and the right eye can not see the left eye image. Now if both images are on the screen at the same time all the time then how are you going to seperate them to go to the correct eye. Each eye would be seeing both images at the same time, and if you take your glasses off when watching a 3d movie at the theater you will notice it does not work. Shutter glasses work in that when the right eye image flashes on the screen the right lens opens. Then it closes and the left lens opens while the left image flashes on the screen and they do this back a forth. So in 2d video you only need one set of images for both eyes but in 3d now you need to get two seperate images of everything for each eye. Now your screen needs to do twice the amount of work than it did before. You can do 3d with 60hz but you will notice the flickering of the switch from right eye to left eye quit easily. At 120hz you can double the amount of switching form eye to eye in a second and the flickering effect will disappear. Unfortunatly field sequencial 3d that uses shutter glasses is really the only alternative right now for television unless you use the red and blue 3d format. Polarized used in theaters is not possible for regular tvs and if polarized does become possible again you will need to buy a tv that can do that format.