3D, it's all the rage these days. I've been looking into making some 3D content, but first, let's look at what exactly it's about!
So there's been a huge craze for 3D of late. Since Avatar, all movies nowadays seem to be throwing in 3D. It was really something a few years ago (remember Spy Kids 3D?), but now there's a new system of 3D display other than the old Red-Blue (actually Cyan) glasses.
Before we get into the making of 3D, it's better to explain how it works!
As I child we wondered why humans have two eyes. I, honestly, thought it's so we have a larger field of view. But weirdly enough, that is not the case.
We have two eyes, and specifically separated but on the same plane, for what is commonly known as Depth Perception. Depth perception is our ability to tell the distances of objects not only from ourselves, but also from one another.
Hold your hand in front of your face at arm's length. Now close one eye, then the other... you'll notice that your arm moves left and right and the screen (or anything else beyond your arm) moves in the opposite direction.
This is caused by parallax (something we know but didn't know what it was called). I really suggest you read that wiki article. It will explain everything.
Our brain now takes the left and right image and compares them. The distance an object moves left/right when compared to each eye is then used to calculate how far away the object is. Even a change of (allow me to say this) 1 pixel would be calculated to give the exact distance of an object.
We really need depth perception. For a good example, hold a pencil in one hand and another in the other hand. Now, close one eye and try to bring the back tips of the pencils to touch. It's not impossible, but I'm sure you'll miss a few times. Open both eyes, and it's very easy!
Okay, that's it for this Science lesson, let's look into how this applies to video.
What happens now is that in order to perceive a third dimension, or depth, our brain needs to receive images with parallax, and in order to do that we need to give each eye something slightly different to look at.
That's how 3D in cinemas (and these 3D TVs) work. The glasses alternate between being black and clear (like close one eye and leave the other open, then switch then switch etc) at the same rate as the image on screen rapidly shows left/right images. They're synced and happen EXTREMELY fast (about 120 times per second, which means each eye sees 60 frames per second). This leads to depth perception.
The next time you have a pair of TV 3D glasses, look out the window, you should see slight flickering.
But what about the Red-Cyan 3D glasses days?
In those days, both images were merged into one, as you'd notice by the double edges.
Red and Cyan are opposites. So, if you looked at the image through a cyan lens, the RED channel wouldn't be visible because it's cancelled out. Same goes for the other way around.
This method is what can be easily pulled off (and cheaply) because making the lenses is only a matter of finding transparent material, like the covers of spiral-bound books, and we don't need a special TV/screen to view it.
The only problem with Red-Cyan is that they cause eye-strain in a VERY short time. They also limit the range of colors that can be used.
Anyway, lately I've been looking into Red-Cyan 3D, and have made a few tests at home that I'll be sharing with you guys soon!
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