Instead of directly explaining it, I will take a different route this time. Let’s take a look at this conversation between Walter and Michael. In case you are not familiar with them, Walter is a mathematician and Michael is his friend who refuses to acknowledge that humans need complex mathematical models. This attitude of Michael doesn’t sit well with Walter and hence they are constantly at loggerheads over this issue. They were once walking along and they came across a multiplex.
The 3D Fascination
Michael: You wanna watch a movie?
Walter: Sure. What do you wanna watch?
Michael: Madagascar 3 came out recently and I have heard good things about it. It’s in 3D as well. Let’s go see it.
Walter: Oh, alright. Do you like 3D movies?
Michael: Totally! They are so cool. It feels like things are happening right in front of your eyes.
Walter: Do you know how it works?
Michael: I guess it has something to do with those funky glasses we wear during the movies.
Walter: That’s right! It definitely has something to do with those funky glasses.
Michael: Do I sense a little sarcasm here? Don’t act like you know exactly how it works!
Walter: As a matter of fact, I do know how it works.
Michael: I’m sure you do! Let’s go watch the movie.
Walter: Who’s being sarcastic now?
The Hazy Request
Walter and Michael went inside the multiplex and bought two tickets. They went inside the theater and the movie started. After around 30 minutes, Walter starts thinking about their earlier conversation and how he can prove to Michael that he actually knows about 3D.
Walter: The 3D effect is good but the storyline is not that great.
Michael: I don’t wanna make a judgment call until I finish this movie.
Walter: Just a small thing. Can you take your glasses off for a second?
Walter: Just take them off and look at the screen.
Walter: What do you see?
Michael: It’s a little blurry. Why would you ask me to do this?
Walter: No particular reason.
Michael: You always do this. Whenever you get bored, you ask me to do weird things and pull me down with you. Not this time! I’m putting them back on.
Someone Is Curious
The movie ended and they came out of the movie theater. They started walking towards the burger place nearby.
Michael: You know, I gotta say the movie was not as good as I thought it would be.
Walter: I guess so. May be your expectations were high after watching the first two Madagascar movies.
Michael: May be! But 3D never fails to amuse me.
Michael: Just out of curiosity, how does 3D work anyway? I have a rough idea of how it works, but I’m not exactly sure.
Walter: Are you accepting that I know about this technology?
Michael: No! We are assuming you do. Let’s see if this assumption is valid.
Walter: Fair enough! You know our two eyes perceive the world differently right?
Michael: Yeah. My friend told me about this some time ago. The same object appears to have moved slightly when you close each eye and switch back and forth.
Walter: Exactly! That happens because our eyes are like cameras placed at different positions. So it’s like taking the picture of the same thing from two different points.
Walter: When we look at the world with both our eyes open, we continuously keep capturing two images simultaneously.
Michael: It’s like overlapping pictures taken from two separate cameras. Why don’t we see two copies of each object then?
Walter: That’s because our brain has the ability to correlate the two captured images even though they are slightly different. It will take all the information and give us the proper depth information. We can easily differentiate between objects which are nearer to us and objects which are far away. This means that if we are in the real world, our brain will see 3D because we are in fact in a 3D world. But if we see a flat screen like a computer or a TV, our brain will know it’s not 3D.
But The Screen Is Flat.
Michael: So how do they do it in the movie theater then?
Walter: We need to trick our brain somehow. If it recognizes that it’s the same image, then it will not perceive it as 3D. We need to show a different image to each eye. Our brain will try to put these images together. Since it has two different images, it will try to make realistic sense of it. Hence we see things come alive in the third dimension. Just like how it happened in case of the real world scenario we talked about earlier!
Michael: How are the images different? I mean, I see the same theater screen with both my eyes. How are my eyes receiving different images?
Walter: This is where the funky glasses come in. The filter in the left frame is different from the filter in the right frame on those glasses. Each filter allows only a particular kind of light to pass through and blocks the other one.
Told You I Knew It.
Michael: See, I knew it had something to do with the funky glasses.
Walter: Of course you did. So when our brain puts these images together, we feel that objects are in 3D.
Michael: We are basically tricking our brain into thinking that there are three dimensional objects.
Walter: Exactly! Remember when I asked you to take your glasses off during the movies?
Michael: Oh yeah! What was that about?
Walter: The reason it was blurry is because there are two images and you are seeing both of them overlapped together. This is done using polarized light.
Walter: The superimposition of the two images on the same screen is done using something called Polarization. The two images are then separated by the filters on your funky glasses.
Michael: Ooooh. That’s right. The filters! There’s so much tech behind this. That’s a lot to take in.
Walter: True that! We live in an amazing time.
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