3D televisions have not been invented yet.

I know what you're thinking. "Luke, I've seen all these advertisements for 3D TVs. I've even tried one out with the glasses at a store." Ah, but all those TVs that are available now, which the companies that manufacture them are so quick to label as "3D" or even "True 3D," aren't 3 dimensional at all. And more than that, they shouldn't be called 3D televisions.

The televisions available now claim to be 3D because they can (through one method or another) send two different images into the left and right eye, simulating depth perception and making the brain think that it is looking at a 3-dimmensional object. However, 3D opjects have more properties than just being perceived with depth. To see what I mean, ogo ahead and pick up a 3D object that you probably have near you; a pen. Hold it close to your face and close your right eye to look at it with just your left eye. Now, quickly close your left eye and look at it with just your right eye. You'll probably notice that the pen seems to have "jumped" to the left. This is because each of your eyes has a slightly different point of view to see the pencil from and your brain pieces together the difference to give you a sense of how close it is to you. This is how current so-called 3D televisions work, by giving you a different image in each eye.

However, like I said, there's more to an object being 3D than just that. To see this, try holding the pen close to your face again. While looking at it, tilt your head to the side. Since the pen is a real 3D object, you notice that as you move your head to the left, the pen seems to move to the right in your field of vision, and visa versa. If this were a current "3D" television you were looking at, instead of a real 3d object, then it would just seem to hover in front of your face when you move it, rather than going from side to side. If you move your head up and down relative to the pen, you should notice the same thing. And finally, if you move your head forward (beside the pen, not directly into it), you'll notice that you can see other angles of the pen; its side and rear which were previously hidden to you. There's quite a bit more ways to look at something that's actually 3D than the "3D televisions available today, right?

That's exactly why we have a long way to go before we truly have 3D televisions. The televisions we have today are important as a stepping stone to that technology. Rather than 3D, let's call them 2.1D displays. They are able to create the illusion of depth perception, but they are still outputting 2D images (just that they're producing 2 2D images at a time). Their are several methods used by displays now to achieve this effect. Some of them are use glasses to create the desired stereoscopic effect, while others use different methods (such as a paralax barrier) to create a stereoscopic effect without the use of glasses. This post will be focusing more on the latter, because I feel that they are closer in nature to their future sucessor.

The next step (which I'll call 2.25D) is to create television displays which can create a whole range of 2D images across the X-axis. Why the X-axis? Because that's the axis on which our eyes are seperated and it feels more nature to move one's head from side-to-side to get a good look at things than it does to move one's head up and down. These televisions will function similar to many glasses-less 2.1D displays now, with one exception. 2.1D displays output 2 images, one for the left and one for the right. 2.25D displays, on the other hand will output an array of images from left to right. This will still produce two different images for each eye, allowing the display to fool our depth perception, but it will also do more than that. It will allow people to see the image differently, by moving their head from side to side (or sitting at a different angle from the TV). Say you're looking at a 2.1D television, straight on. Your left and right eyes will be receiving different images. Now, if you move your head 2 inches to the left so that your right eye is where your left eye was, your eyes wont be getting any different perspective than they were before. What's more, because you're not perfectly alligned with the center of the television, you will lose the depth perception. On a 2.25D television, on the other hand, if you moved your head two inches to the left, your right eye would now be seeing what your left eye was seeing before and your left eye will see an entirely new image for the position its in. If you continue moving left, your left eye will continue to see new images for the different angles as it moves. This allows the 2.25D display to further replicate real-life objects by allowing you to view them at different angles

After that would be what I call 2.5D television. This would be very similar to 2.25D displays, except for the fact that in addition to the multiple angles of view on the X-axis, there will also be mutiple angles of view on the Y-axis. This will be a more difficult step because it will require exponentially more tenderings (for viewing of computer generated graphics) or image sensors (for recording video footage) to be seen on the screen. However, the effect will be amazing. The screen will appear to be a window into a non-existant world. Much like a real window, you will be able to peer into it from different angles in order to see different things that would otherwise be hidden by the frame. At the same time, the stereo viewing effect could be used to cause objects to appear at various distances from the window. It could even be used to make it appear that objects were passing through the window and getting even closer to the vuewer. However these objects would lose their realism as the viewer would stop seeing them if they moved their head so that it was no longer completely in front of the window (from their field of vision).

The final step would be an actual 3-dimmensional display of some kind. Whether this would still be achieved with a screen as we know it today or by some other kind of image generator is yet to be seen. The effect would be amazing. Rather than imagine it as a display or a screen, it might be better to think of it as a hologram (as they are portrayed in science fiction movies). It would be able to create the appearance of an object inside the room (outside of the display itself), which you could then walk around and view from any angle as though it were really there. Aside from trying to touch it, it would seem like this object was really in the room, in every way. That would be a true 3D display.

If you consider something like a real 3D display and then think back to the 2.1D displays we have now, you can see that we have a long way to go. We as a society (and, more importantly, the companies marketing the displays) don't need to be patted on the back and congradulated for creating 3D televisions quite yet. If we start thinking that what we have now are really 3D displays, it kind of lowers the incentive to get to work on the real ones. What we have now is certainly an accomplishment, but it's not nearly as much of an accomplishment as when we actually start producing 3D displays.