Brought to you by the reinvented two thousand twelve camera. It's ready. Are you get in touch with technology? With tech Stuff from how stuff works dot com. Hello again, everyone, and welcome to tech stuff. My name is Chris Pallette. I'm an editor at how stuff works dot com, and sitting across from me, as always, is senior writer Jonathan Strickland. Well, you know it's that old shark screen, the bubble screen. You know, sharks don't like that. It's what they call a marine segregation. Okay, then that that quote comes from a movie that was in three D, and it leads us to our first in a long time listener mail. This listener mail comes from Calvin, and Calvin says, I was thinking that with movies like Avatar, Yes, I'm ill talking about Avatar and other big three D sort of c g I movies like Alice in Wonderland. Maybe a podcast on that would be fun. Any who, keep up the good work. Calvin B. From Minnetonka, Minnesota. All right, so we're gonna talk a little bit about three D movies. Now, we've talked about three D glasses in the past and three D television, but we really didn't go into the whole process of making a three D film or or three D video. Um and so we thought this would kind of fall into our movie making technology series. I agree, and I think it would be nice to start with a refresher about the three D glasses because that has a lot to do with how you make a movie and the reason why you make the movie the way you do. That's a good point. So let's start with talking about what makes three D three D in the first place. Okay, So the first thing you need to know is that we perceived depth through many different um ways. But one of those ways is through what we call parallax. And parallax is the difference in viewing angle between one eye and the other eye. So, if you were looking at an object that's a few feet away from you, you know your left eye in your right eye are not They're not located exactly in the same spot, otherwise you'd be a cyclops. Uh. So that means that your your brain is getting two sets of images that are slightly offset from each other, and it incorporates those two sets of images into a single image in your head. And so that's that's one of the ways we perceive depth. There are other ways as well, like visual cues of the size of something, and judging by the size, you kind of figure out how far away it is. And parallax only really works to a certain distance anyway. Once you get beyond you know, I don't know, I think it's like twenty or thirty feet, parallax doesn't play as big a role because it's getting far in the objects, getting far enough away where your eyes are getting closer and closer to being parallel. So if you focus on something that is effectly an infinite distance away, and of course that's you know, I'm saying effectively infinite. So for example, example a star out you know, if you're looking at a starry sky, the distance of that object is so far away that your eyes are essentially in parallel with one another. They're not converging at all. But parallax is a very important part of of getting a three D effect, especially on film or video and um so, the idea is that you have to present two different sets of images. Each set of images is going to be perceived by only the left or the right eye, and then when your brain sees, when your brain senses these two sets of images, that combines them into a single image that has the illusion of depth. Well, yeah, I mean there are there are two different types of of three D glasses, of course, the older one being the Anaglyph method and the newer one being the polarized version. Anaglyph was the one that had the two different colored lenses. Yeah, it was either a red or blue, or red or green. And now you were saying to me earlier red and cyan. It's sort of the the accepted color and uh and the polarized ones. What that means is that the lenses are polarized to allow light that is aligned a certain way to pass through, and light that's aligned and I think it's ninety degree um other alignment that that light will not pass through the lens. So each lens is letting one kind of light through and blocking the other kind. Yeah, I think that's probably more sophisticated way of doing at The Anaglyph method required a red layer and a blue or green layer of the movie so that the glasses could interpret the images correctly, because, for example, the red lens uh makes the other color appear darker, so you see that better through that eye, and then the blue lens is the opposite. It makes the red uh frame is it? Frame would be the right word? Layer layer, Yeah, red layer show up better. Um, So it appears three D and because of the spacing between the two images, that's what gives the the illusion of depth. Right. The two images are offset, and of course that's really important because if they weren't offset, all you'd be doing is making a really lousy, fuzzy image for no good reason. Yes, which is kind of how it looks when you're not wearing the glasses. Yes, and there there is one a third type of of glasses that we should talk about, although this is I don't think it's ever used in films. I've never been to a movie where they used this method. But that's the shutter lens method, like the active active glasses, which are more often used for things like computers or sun Television systems are also experimenting with active glasses. Now. Active glasses require a power supply and they actually have a little l C D shutters in them that shutter on and off at incredible speeds. So to you, when you're wearing the glasses, it doesn't appear like they're shuttering on and off at all, but they really are and the images you're looking at are are are Wow. I had the word there you go synchronized with each lens, thank you. Um yeah, that was my brain gave out on me. But yes, like the the left lens would be synchronized with one set of images, the right lens would be synchronized with the other set of images. They would alternate those images at a speed that is uh so fast that you can't really tell when you just look at it. And um, so again, each eye would be getting one set of images at a certain alignment. Your brain would be putting all the information together and you get the illusion of depth. UM. Projectors have trouble with that. You have to have a projector that can can run at an incredibly fast frame rate for that to work, because you're you're you're shooting two different sets of images, um, but not at the same time. They're alternating so quickly that you have to you know, you have to keep that frame rate up really really high in order to maintain that illusion. These other methods, the polarized method, the anaglyph method, you can have both sets of images on the same strip of film. Uh, you know, it's just it's two different layers on a on a on one strip of film, so you don't have to alternate images back and forth, you know. So, um yeah, and your brain is doing all the work here. That's the great thing is that once you once you've developed the technology, the brain does everything else. All the special effects are supplied by you. However, it does mean that if you have suffered some vision loss, or if you have some other ailments, you may not be able to perceive three D in a three D film, right, So, but you'll still need the glasses unfortunately, because if you don't have the glasses, you're going to get that fuzzy effect that Poulette was talking about. It's gonna look like two sets of images on one strip of film, and that's not a really pleasant viewing experience, as anyone who's taken glasses off during a three D film could tell you. Right. But the trick is how do you actually make the movie so that it will appear in three D? Yeah, there's there are three main methods of doing this. Okay, There's there's converting a two D film into three D. There's shooting a film in three D to start with, and then there is using a computer generated film, and then you artificially create a second camera within your c g I world, and you make your film three D that way. Okay, I was kind of I was kind of lumping that in my head with the first one, which was taking the original and then doing something to it to make it three D. Yeah, it's when you said three I was going, Okay, I don't know that. It's kind of a bridge between the two when you think about it, because you're you're creating a virtual camera, so in a way, it's acting like you are actually using you like you're filming in three D from the beginning. But like you said, it's also incorporating some of the elements of conversion of two D to three D. Um let's talk a little bit about about the well, which one would you like to tackle first? Well, I was thinking that one of the things that's important to note here is that live action is much more difficult to convert to three D than computer graphics for the reason that you just brought up, which is in the computer graphic version, you can do things with the computers to you know, create a different camera angle, uh, you know, so that you would be able to do that a little bit more readily than you could with live action. So I think we should probably start with the traditional method of doing live action because three D movies have been around for quite some time since you're sure. Yeah, like you were saying with the the just to tag on what you were talking about with the c g I movies, UM, yeah. The wonderful thing about c g I movies if you're a filmmaker is that you are not limited by the laws of physics, so you can create a camera angle that is the ideal angle, uh, to go with the other camera shots, so you know you can you could create two camera angles where the lenses would be the perfect lengths or the perfect distance between the two in order to create the three D effect, whereas in the real world most cameras are bulky and you can't get the lenses physically close enough to uh to mimic what you would see if you were standing there. Um. It's it's called the interocular distance. It's the distance between your eyes. Now, before we get into the actual physics of shooting, UM, I was just gonna quickly mention that the average interocular distance for a man is about sixty five millimeters for a woman, it's about sixty three millimeters and for a child it's about fifty one millimeters. So the average interocular distance used in three D filming is about sixty four millimeters. And most most cameras you just can't get two lenses that close together because the camera, the physical bulk of the camera prevents it. So, for example, if you had two red cameras, which we talked about that in the past, those are the really high definition cameras. That's a brand name. Yeah, yeah, not a description, right, exact, thank you, thank you. Yes. When I'm saying red cameras, I'm not talking about the color red, I'm talking about a brand R E. D all in caps. Uh. If you were to get two of those and set them next to each other, the closest you'll be able to get the lenses is about a hundred and twenty five millimeters, So that's almost twice the distance as what you would need if you wanted to create kind of a natural looking effect that was easily translatable into stereoscopic vision um once you were finished. And uh so that's a problem there there, and there are ways around that, but we'll get into that. So you were going to talk about some of the historical three D films, or at least the historical methods were just a little bit of it. Um. Yeah, I mean traditionally the way to do this since the the least according to Britannica, the typical distances between two and a half to two and three quarters inches, which, as you were pointing out, is about six point four centimeters to seven centimeters. Um. You know, there there are a couple different ways of doing this. You could put a couple different cameras side by side, although as you pointed out, that can be difficult, Or you can use a camera with two lenses, um, which seems awfully specialized and probably very expensive compared to some of the other methods of doing this. Um. Actually, the very first film, according to Britannica again to be you made using the natural vision process was Buanna Devil in two um. Although there there were some experiments uh done in the nineteen twenties and thirties using three D, but it was edwin Land. You know that name. It should sound familiar to you. Uh. It's not ringing any bells. He he created a polarizing material in nineteen thirty two. That the natural vision method is based on And that's the kind that of glasses that we were talking about earlier, not the anaglyph blue slash green slash san um. These are the lenses that look almost like their sunglasses, but they are not sunglasses. They're not do not wear them as sunglasses. Is their polarized And he was the inventor of the polaroid land camera. Got you, Um, but yeah, I mean he was. He was one of the people who were working on this and that that was you know, a long long time ago. But you know that's uh, that sort of water under the bridge, and there were a lot of people trying to do this. Um. You know, back when the Natural Vision System came out. Three D became big for a while, and a lot of people made a lot of very bad three D movies. It seems to move in cycles. We talked about this, I think in our three D Glasses podcasts as well, about how three D films seemed to come up as a gimmick for like every twenty to thirty years because they were they got really big in the fifties and then they kind of, you know, the processes just were not refined enough for it to really take off. Um, it just it came across as a gimmick. And then they had another resurgence in the eighties. Uh, which that's the era from which my quote uh derived. But then the quotes don't stop at the edge of the podcast, that's right. Uh, so the nice So they the the eighties had another little resurgence of of three D. But again the techniques still weren't truly refined, and so there were some problems. And I guess we'll talk about that in a little bit too. Uh. And then now we've got some point where digitally we're able to uh to correct some of those problems and and and head off some of those problems, so that we really have reduced the the the factors that made viewing three D less than a pleasant experience for some people. Um. And I guess I guess I can hit that really quickly right now. If since your brain is is creating this picture in your head and creating this illusion of three D, uh, if stuff is not aligned properly on the screen, your brain has trouble with that, right, So it has to be done just right or it's not gonna it's going to not work. In the opposite way, it's not not just going to be not convincing, it's going to actually be upsetting. Yeah, kind of like the way for example, here's here's a very simple way where it can it can really mess with your brain. Uh, we're not We can handle horizontal differences, you know, where you're shifting the image to the left or to the right a little bit. In fact, that's what three D is all based on. If we didn't shift the images, then you wouldn't get the three D u vertically, not so much. You shift an image so one image set of images is slightly higher than the other. That's gonna create a really weird distorted field for your brain to handle, and that can actually make audiences uncomfortable and and sick or give them eyestrain or headaches and a lot. And because the early early methods of creating three D films didn't always have everything stuch up just perfectly. I mean you're talking about using physical cameras and physical film to create two different versions of the same image. Um that that meant that just a tiny misalignment could cause an entire audience to start yakking, very much like the stand by Me infamous scene. Anyway, So you don't want that to happen. As it turns out, it's not great publicity to say that, Hey, audiences have been throwing up at this film for for for weeks now. Did you work for the Blair Witch Project? It worked for me anyway, So, but that wasn't the three D film. Don't write us so. Yeah, but but there was emotion remember the camera, Yes, yes, the idea was it was supposed to simulate somebody walking around with a handheld video game and the motion made people sick because we're bouncing around. Clover Field did the same thing there. They're quite a few handheld films out there now and I think people are starting to get a little more used to them. But yeah, you might want to take a drama mean before you go into the getter for that kind of thing. That is not medical advice, by the way. That's just me making a joke. Um anyways, just heading off the emails. Uh so, yeah, if now that we have the digital approach, it's a lot easier to correct for these problems. So that we've really reduced the factors that create things like eye strain and make people nauseated. We've managed to maybe not eliminate them, but dramatically reduce those elements. So yeah, so you're talking about the having two cameras next to each other or a camera with two lenses. Um, there's also there are also other ways that you can try and get to additional ways that you can try and get the three D effect. So let's say you're using two cameras and you cannot get these two cameras close enough to get to that ideal interocular distance. So what you might want to try and do is you'd have to find a way to direct the image the light in such a way so that it looks like the two lenses are next to each other. So you might have to use prisms and mirrors and a really really elaborate camera by camera rig Uh. These things are are bulky. They make shooting much more difficult. So shooting in three D is a difficult and expensive process. Yes, you know, you're either going to need specialized equipment so that's gonna cost more, like you said before, or you're going to need twice the equipment that you normally would need because you're gonna need, you know, two cameras instead of just one for every single kind of camera shot that you're going to be doing uh, and you're gonna need specialized rigging or mirrors or whatever, and those all have to be set up just right, because if you have a mirror that's not aligned properly, you're not going to get that stereoscopic effect. And then, of course there's a further argument you can have. Do you have both cameras shoot in parallel, so in other words, both cameras are facing directly forward, or do you arrange it so that the cameras converge slightly Because our eyes converge, true, so if you want to have the cameras converge, you have to set that up. And it's a really exacting, precise process, and if you get it wrong, the effect is going to be ruined. So shooting in three D is really complicated and really expensive. There are those who will argue that it's the only way to get three D, right, Yeah, And the thing is really when when you get right down to it, there's nothing inexpensive about three D because the conversion process is also very expensive. Yeah, it can be. Up to the general rule of thumb in the industry for converting a two D film into three D is one hundred thousand dollars per screen running time. So yeah, a hundred and twenty minute movie is gonna cost a hundred thousand dollars times a hundred and twenty and so that's yeah. You start you start adding up and you're like, wow, that's really expensive. It's still cheaper than shooting it all in three D, assuming that you again that you're shooting live action. Well, because again c g I, we've already mentioned that you could just create a a virtual camera and get that effect all on its own. So c g I is easy. Comparatively speaking, It's still gonna take a lot of time. It's gonna take up a lot of hard drive space, and it's not like, you know, it's not like it's a walk in the park. But compared to the problems you face from doing live action, it's it's fairly simple. But let's talk a little bit about the conversion process of two D to three D. Okay, Yeah, I was actually gonna to uh mentioned, especially to your point about how much it costs um the company that did the conversion for Alice in Wonderland, as that company called in three and uh, it can charge. It charges something along the lines of fifty thousand two hundred thousand dollars per minute of time needed to do that. So you think about that in terms of you know, per screen, you're thinking this is really not cheap. Yeah, yeah, I mean you can. I guess you do it once for a master and then you run copies. But at any rate, the uh, yeah, it's expensive and the processes is complicated because what you have to do is, let's say you've got someone gives you a film and by the way, you can do this yourself. I'll tell you at the end of the podcast about a program that will allow you to convert two D movies into three D movies UM using some some open source software. It's pretty cool stuff. It takes a lot of time and it takes a lot of processing power. So if you've got an older computer, this is probably not something you want to try because unless you don't you know, need your computer for three or four weeks um. But converting two D to three D, the first thing you do is you've got this flat image because you know it wasn't filmed in three D, so you have to divide that image into a series of layers, and it's generally between two to eight layers Okay, two layers would be the bare minimum because of course, you know, you need to have that those two layers to create that that sense of depth, and really the number of layers you have per frame depends upon how much stuff is on screen at that time. Yeah, that makes sense. So there was a great example, uh I read about this uh on on slate. Actually there's a great example of talking about a guy standing in front of a brick wall. That might just be two layers that you create there, or two or three. And so once you've figured out what the layers are, next an artist has to go in an outline the object that is, you know, that's going to be at a specific depth. Um, So every single object in the image has to be outlined so that the computer program that you're going to run this through will be able to to calculate what depth each image needs to be in. And then you kind of turn every single image that's on that or every single object that's in that image rather into kind of a topographical map that makes yeah. Yeah, so this is what's telling the computer which parts of that image are should be closer to the eye of the viewer. Because of course, in the three dimensional objects some bits are going to be closer to you than others. So let's say that you're looking at an airplane head on, the nose of the airplane is going to be closer to you than the wings of the airplane, right, So you need to make sure that you you design this topographical map so that the computer realizes, oh, the nose is the front, that's what that's what needs to be closest to the eye. So we're gonna shift that this much for the two images, whereas the wing is further back, we're going to shift that a different distance to create the proper illusion of depths. You have to do this frame by frame, yes, And it's that's why it gets really expensive because it it's a process that requires both manual work and computer programs. It's it's not something that you can just you know, you can't just chunk a two D movie into a what you can, but it doesn't necessarily work. You can't just chunk a two D move into a computer program and expect a great three D film to come out. Now. It's it's it's got to be done slowly and carefully, which is probably why it's so expensive. Um, the the inn three process UH starts with their previous pre visualization or previous program and then they actually use a technique they call dimensionalization, which well, okay, it's pretty self descriptive, but um, during the process they get the directors involved, and what they'll do is they basically can control the depth, shape, and perspective of different objects to tailor the image what's there now, to the screen size that it's going to be shown on, and and to give people, you know, for example, IMAX versus a regular size, regular ish sized movie screen. Not like there's anything that's particularly regular about that, um, but yeah, I mean it's they have control over over that. And maybe one scene doesn't need so much three dimensionalization to make it a peer three D and another requires more. So they go in and scene by scene, frame by frame, they have an opportunity to take control of that. UM. They actually have a soft particular software package that they use, their own homegrown stuff called Intrigue UM. But yeah, I mean it allows them to stay consistent shot to shot, and then they go through a depth grading process that you know, it allows them to do the screen size things, so they can have control over everything. And that's just another reason why it takes so long. But the studios that do this um uh in three and there's another one called Prime Focus that's based in Mumbai. They're the ones who did Clash the Titans, by the way, cost about four point five million dollars according to the Hollywood Reporter. I read an article by A Carol and Giardina, and so, I mean, they all have their own proprietary way and they sort of tell you what's going on, but they don't really get into, if you will, in depth on the matter. But let's talk about some of the problems of converting two D to three D, because there are some quite a few, uh, and there are directors out there, James Cameron among them, who are adamant that this approach is flawed and results in bad movies, or at least technically bad movies. Not necessarily that you know, the script is bad or whatever, but technically it is. Visually. Visually yes it is. It is an inferior product. And Cameron will argue that shooting in three D is really the only way to go right now because our conversion process just isn't good enough. And some of that is understandable because some movies have been converted to three D. Were never intended to be in three D in the first place. But actually he uh, it's kind of ironic in a way because he's partially to uh to blame, not blame, but he's he's partially the reason why everybody is rushing to make three D movies right now because the successive Avatar. Well yeah, I mean when you think about it, that makes it makes perfect sense from Hollywood's perspective, because shooting and releasing a three D film means you can charge more, and it's it's capitalizing on the three D craze right right. Everybody's excited about it, so they wanted so it's do another one. It's easier to make a lot of money because you don't have to sell as many tickets to make as much to make a huge box office. But as well as the fact that it's cashing in on a craze. Uh So, some of the problems with converting two D to three D is is if it wasn't shot meant if it wasn't meant for three D, you may not be getting that. You know, the three D effects that you see may not be that that good. The sense of depth may not really be there because it wasn't intended to be there, that wasn't part of the original vision. Another problem is that sometimes if the if the conversion process is a poor one, and sometimes it is, you end up with what looks like a bunch of cardboard cutouts that are at different in depths. So there is a sense of depth, but there's not a sense of three dimensions. And I've seen this happen with a lot of software that converts two D photos to three D photos in real time, and it looks like, yeah, it looks like, hey, that's not Bill, that's a cardboard cut out a bill. But the cardboard cut out a Bill is closer to the camera than the cardboard cutout of Sarah. It's not at all convincing, and it's actually distracting. That guy always left me a little flat to begin with. Ha ha, such a two dimensional character. Uh. The Another problem is that these films are shot. The two D films may be shot with a certain idea of what the level of light needs to be. Well, when you converted to three D, one of the problems is that if you're using the polarized lenses, that means that the image you're gonna see is already going to be a little darker than what was necessarily intended originally, so you end up with scenes that are darker than the director had intended. This was a big problem, one of many for Avatar The Last Airbender. There were scenes or shot at night that you could not you couldn't tell what was going on because by the time you had the glasses on, it made the shots so dark that you couldn't see anything. Right. Um, now I'm going to wrap this up really quickly. We've pretty much covered how this works. Yeah, I did mention that I was going to talk about how you could convert your own like convert two D movies to three D movies. Sure, there's Uh, there's this great program called avicynthe A v I S y n t H and it's it's free, you can get This is actually kind of a codec more than anything else. So, uh, it's which means it plugs into U to something like Windows Media Player and allows you to read files that have been encoded with right. Right, it's not it's not its own it doesn't have its own user interface. It's not like you would run this program and something would pop up. Um, I got this, by the way from maximum pc so if you want, did you Yeah, it's an article by Alex Castle at maximum pc UM. The article title is how to upgrade your two D movies to three D, So if you want to look into it in detail, I recommend checking out that article. But in general, what does is it provides you a uh so the ability to to create three D films. You have to grab some code UH and the article tells you where to go to get the code. It's from a three D vision blog. And when you put this code in, you can actually convert a two D film into three D. It will create two sets of images. UH. It's a designed to work with Nvidia's three D system, so you need the Nvidia UH graphics card and a Navidia glasses and or if it leads to work. But it also has a setting where you can switch it to anaglyph if you want to, so you wouldn't in that case if you just switch it to anaglyph, you just need the anaglyph glasses in order to view it. But keep in mind that when you're viewing stuff with anaglyph glasses, that means that the color is going to seem a little off. It's not going to be as vibrant again. Um, so there are some issues. And just like we were talking about with the three D conversion thing, if you're using polarized glasses or really it's the act of shutter glasses, it may be a little darker than what the movie was originally intended to be, so you may have to adjust your brightness settings in order to be able to see everything properly, and that may affect the quality of the film. But yeah, check that out if you are interested in doing this yourself, Remember that it's going to take a lot of processing power and a lot of hard drive space if you want to save these, and they actually go into another open source program that will allow you to save the films. Because avicynthe is really a real time conversion thing. It's not designed to save the movie that you've converted. It's just designed to to kind of do the conversion on the fly. If you want to save it, you're gonna need to use a separate set of programs and codex. But maximum PC spells that all out, and the three D Vision blog also does so if you're interested, check that out. Okay, all right. That sums up our movie making Technology three D podcast spectacular. I hope you guys enjoyed it. If you have any questions or you want to hear more about the stuff, or you've got a totally different topic you would like to hear us talk about, you can write us our email addresses tech Stuff at how stuff Works dot com and Chris and I will talk to you again really soon if you're a tech stuff and be sure to check us out on Twitter text stuff hs wsr handle, and you can also find us on Facebook at Facebook dot com slash tech Stuff h s W for more on this and thousands of other topics. Does it how stuff works dot com and be sure to check out the new tech stuff blob now on the how Stuff Works home page, brought to you by the reinvented two thousand twelve camera. It's ready, are you

Brought to you by the reinvented two thousand twelve camera. It's ready. Are you get in touch with technology? With tech Stuff from how stuff works dot com. Hello again, everyone, and welcome to tech stuff. My name is Chris Pallette. I'm an editor at how stuff works dot com, and sitting across from me, as always, is senior writer Jonathan Strickland. Well, you know it's that old shark screen, the bubble screen. You know, sharks don't like that. It's what they call a marine segregation. Okay, then that that quote comes from a movie that was in three D, and it leads us to our first in a long time listener mail. This listener mail comes from Calvin, and Calvin says, I was thinking that with movies like Avatar, Yes, I'm ill talking about Avatar and other big three D sort of c g I movies like Alice in Wonderland. Maybe a podcast on that would be fun. Any who, keep up the good work. Calvin B. From Minnetonka, Minnesota. All right, so we're gonna talk a little bit about three D movies. Now, we've talked about three D glasses in the past and three D television, but we really didn't go into the whole process of making a three D film or or three D video. Um and so we thought this would kind of fall into our movie making technology series. I agree, and I think it would be nice to start with a refresher about the three D glasses because that has a lot to do with how you make a movie and the reason why you make the movie the way you do. That's a good point. So let's start with talking about what makes three D three D in the first place. Okay, So the first thing you need to know is that we perceived depth through many different um ways. But one of those ways is through what we call parallax. And parallax is the difference in viewing angle between one eye and the other eye. So, if you were looking at an object that's a few feet away from you, you know your left eye in your right eye are not They're not located exactly in the same spot, otherwise you'd be a cyclops. Uh. So that means that your your brain is getting two sets of images that are slightly offset from each other, and it incorporates those two sets of images into a single image in your head. And so that's that's one of the ways we perceive depth. There are other ways as well, like visual cues of the size of something, and judging by the size, you kind of figure out how far away it is. And parallax only really works to a certain distance anyway. Once you get beyond you know, I don't know, I think it's like twenty or thirty feet, parallax doesn't play as big a role because it's getting far in the objects, getting far enough away where your eyes are getting closer and closer to being parallel. So if you focus on something that is effectly an infinite distance away, and of course that's you know, I'm saying effectively infinite. So for example, example a star out you know, if you're looking at a starry sky, the distance of that object is so far away that your eyes are essentially in parallel with one another. They're not converging at all. But parallax is a very important part of of getting a three D effect, especially on film or video and um so, the idea is that you have to present two different sets of images. Each set of images is going to be perceived by only the left or the right eye, and then when your brain sees, when your brain senses these two sets of images, that combines them into a single image that has the illusion of depth. Well, yeah, I mean there are there are two different types of of three D glasses, of course, the older one being the Anaglyph method and the newer one being the polarized version. Anaglyph was the one that had the two different colored lenses. Yeah, it was either a red or blue, or red or green. And now you were saying to me earlier red and cyan. It's sort of the the accepted color and uh and the polarized ones. What that means is that the lenses are polarized to allow light that is aligned a certain way to pass through, and light that's aligned and I think it's ninety degree um other alignment that that light will not pass through the lens. So each lens is letting one kind of light through and blocking the other kind. Yeah, I think that's probably more sophisticated way of doing at The Anaglyph method required a red layer and a blue or green layer of the movie so that the glasses could interpret the images correctly, because, for example, the red lens uh makes the other color appear darker, so you see that better through that eye, and then the blue lens is the opposite. It makes the red uh frame is it? Frame would be the right word? Layer layer, Yeah, red layer show up better. Um, So it appears three D and because of the spacing between the two images, that's what gives the the illusion of depth. Right. The two images are offset, and of course that's really important because if they weren't offset, all you'd be doing is making a really lousy, fuzzy image for no good reason. Yes, which is kind of how it looks when you're not wearing the glasses. Yes, and there there is one a third type of of glasses that we should talk about, although this is I don't think it's ever used in films. I've never been to a movie where they used this method. But that's the shutter lens method, like the active active glasses, which are more often used for things like computers or sun Television systems are also experimenting with active glasses. Now. Active glasses require a power supply and they actually have a little l C D shutters in them that shutter on and off at incredible speeds. So to you, when you're wearing the glasses, it doesn't appear like they're shuttering on and off at all, but they really are and the images you're looking at are are are Wow. I had the word there you go synchronized with each lens, thank you. Um yeah, that was my brain gave out on me. But yes, like the the left lens would be synchronized with one set of images, the right lens would be synchronized with the other set of images. They would alternate those images at a speed that is uh so fast that you can't really tell when you just look at it. And um, so again, each eye would be getting one set of images at a certain alignment. Your brain would be putting all the information together and you get the illusion of depth. UM. Projectors have trouble with that. You have to have a projector that can can run at an incredibly fast frame rate for that to work, because you're you're you're shooting two different sets of images, um, but not at the same time. They're alternating so quickly that you have to you know, you have to keep that frame rate up really really high in order to maintain that illusion. These other methods, the polarized method, the anaglyph method, you can have both sets of images on the same strip of film. Uh, you know, it's just it's two different layers on a on a on one strip of film, so you don't have to alternate images back and forth, you know. So, um yeah, and your brain is doing all the work here. That's the great thing is that once you once you've developed the technology, the brain does everything else. All the special effects are supplied by you. However, it does mean that if you have suffered some vision loss, or if you have some other ailments, you may not be able to perceive three D in a three D film, right, So, but you'll still need the glasses unfortunately, because if you don't have the glasses, you're going to get that fuzzy effect that Poulette was talking about. It's gonna look like two sets of images on one strip of film, and that's not a really pleasant viewing experience, as anyone who's taken glasses off during a three D film could tell you. Right. But the trick is how do you actually make the movie so that it will appear in three D? Yeah, there's there are three main methods of doing this. Okay, There's there's converting a two D film into three D. There's shooting a film in three D to start with, and then there is using a computer generated film, and then you artificially create a second camera within your c g I world, and you make your film three D that way. Okay, I was kind of I was kind of lumping that in my head with the first one, which was taking the original and then doing something to it to make it three D. Yeah, it's when you said three I was going, Okay, I don't know that. It's kind of a bridge between the two when you think about it, because you're you're creating a virtual camera, so in a way, it's acting like you are actually using you like you're filming in three D from the beginning. But like you said, it's also incorporating some of the elements of conversion of two D to three D. Um let's talk a little bit about about the well, which one would you like to tackle first? Well, I was thinking that one of the things that's important to note here is that live action is much more difficult to convert to three D than computer graphics for the reason that you just brought up, which is in the computer graphic version, you can do things with the computers to you know, create a different camera angle, uh, you know, so that you would be able to do that a little bit more readily than you could with live action. So I think we should probably start with the traditional method of doing live action because three D movies have been around for quite some time since you're sure. Yeah, like you were saying with the the just to tag on what you were talking about with the c g I movies, UM, yeah. The wonderful thing about c g I movies if you're a filmmaker is that you are not limited by the laws of physics, so you can create a camera angle that is the ideal angle, uh, to go with the other camera shots, so you know you can you could create two camera angles where the lenses would be the perfect lengths or the perfect distance between the two in order to create the three D effect, whereas in the real world most cameras are bulky and you can't get the lenses physically close enough to uh to mimic what you would see if you were standing there. Um. It's it's called the interocular distance. It's the distance between your eyes. Now, before we get into the actual physics of shooting, UM, I was just gonna quickly mention that the average interocular distance for a man is about sixty five millimeters for a woman, it's about sixty three millimeters and for a child it's about fifty one millimeters. So the average interocular distance used in three D filming is about sixty four millimeters. And most most cameras you just can't get two lenses that close together because the camera, the physical bulk of the camera prevents it. So, for example, if you had two red cameras, which we talked about that in the past, those are the really high definition cameras. That's a brand name. Yeah, yeah, not a description, right, exact, thank you, thank you. Yes. When I'm saying red cameras, I'm not talking about the color red, I'm talking about a brand R E. D all in caps. Uh. If you were to get two of those and set them next to each other, the closest you'll be able to get the lenses is about a hundred and twenty five millimeters, So that's almost twice the distance as what you would need if you wanted to create kind of a natural looking effect that was easily translatable into stereoscopic vision um once you were finished. And uh so that's a problem there there, and there are ways around that, but we'll get into that. So you were going to talk about some of the historical three D films, or at least the historical methods were just a little bit of it. Um. Yeah, I mean traditionally the way to do this since the the least according to Britannica, the typical distances between two and a half to two and three quarters inches, which, as you were pointing out, is about six point four centimeters to seven centimeters. Um. You know, there there are a couple different ways of doing this. You could put a couple different cameras side by side, although as you pointed out, that can be difficult, Or you can use a camera with two lenses, um, which seems awfully specialized and probably very expensive compared to some of the other methods of doing this. Um. Actually, the very first film, according to Britannica again to be you made using the natural vision process was Buanna Devil in two um. Although there there were some experiments uh done in the nineteen twenties and thirties using three D, but it was edwin Land. You know that name. It should sound familiar to you. Uh. It's not ringing any bells. He he created a polarizing material in nineteen thirty two. That the natural vision method is based on And that's the kind that of glasses that we were talking about earlier, not the anaglyph blue slash green slash san um. These are the lenses that look almost like their sunglasses, but they are not sunglasses. They're not do not wear them as sunglasses. Is their polarized And he was the inventor of the polaroid land camera. Got you, Um, but yeah, I mean he was. He was one of the people who were working on this and that that was you know, a long long time ago. But you know that's uh, that sort of water under the bridge, and there were a lot of people trying to do this. Um. You know, back when the Natural Vision System came out. Three D became big for a while, and a lot of people made a lot of very bad three D movies. It seems to move in cycles. We talked about this, I think in our three D Glasses podcasts as well, about how three D films seemed to come up as a gimmick for like every twenty to thirty years because they were they got really big in the fifties and then they kind of, you know, the processes just were not refined enough for it to really take off. Um, it just it came across as a gimmick. And then they had another resurgence in the eighties. Uh, which that's the era from which my quote uh derived. But then the quotes don't stop at the edge of the podcast, that's right. Uh, so the nice So they the the eighties had another little resurgence of of three D. But again the techniques still weren't truly refined, and so there were some problems. And I guess we'll talk about that in a little bit too. Uh. And then now we've got some point where digitally we're able to uh to correct some of those problems and and and head off some of those problems, so that we really have reduced the the the factors that made viewing three D less than a pleasant experience for some people. Um. And I guess I guess I can hit that really quickly right now. If since your brain is is creating this picture in your head and creating this illusion of three D, uh, if stuff is not aligned properly on the screen, your brain has trouble with that, right, So it has to be done just right or it's not gonna it's going to not work. In the opposite way, it's not not just going to be not convincing, it's going to actually be upsetting. Yeah, kind of like the way for example, here's here's a very simple way where it can it can really mess with your brain. Uh, we're not We can handle horizontal differences, you know, where you're shifting the image to the left or to the right a little bit. In fact, that's what three D is all based on. If we didn't shift the images, then you wouldn't get the three D u vertically, not so much. You shift an image so one image set of images is slightly higher than the other. That's gonna create a really weird distorted field for your brain to handle, and that can actually make audiences uncomfortable and and sick or give them eyestrain or headaches and a lot. And because the early early methods of creating three D films didn't always have everything stuch up just perfectly. I mean you're talking about using physical cameras and physical film to create two different versions of the same image. Um that that meant that just a tiny misalignment could cause an entire audience to start yakking, very much like the stand by Me infamous scene. Anyway, So you don't want that to happen. As it turns out, it's not great publicity to say that, Hey, audiences have been throwing up at this film for for for weeks now. Did you work for the Blair Witch Project? It worked for me anyway, So, but that wasn't the three D film. Don't write us so. Yeah, but but there was emotion remember the camera, Yes, yes, the idea was it was supposed to simulate somebody walking around with a handheld video game and the motion made people sick because we're bouncing around. Clover Field did the same thing there. They're quite a few handheld films out there now and I think people are starting to get a little more used to them. But yeah, you might want to take a drama mean before you go into the getter for that kind of thing. That is not medical advice, by the way. That's just me making a joke. Um anyways, just heading off the emails. Uh so, yeah, if now that we have the digital approach, it's a lot easier to correct for these problems. So that we've really reduced the factors that create things like eye strain and make people nauseated. We've managed to maybe not eliminate them, but dramatically reduce those elements. So yeah, so you're talking about the having two cameras next to each other or a camera with two lenses. Um, there's also there are also other ways that you can try and get to additional ways that you can try and get the three D effect. So let's say you're using two cameras and you cannot get these two cameras close enough to get to that ideal interocular distance. So what you might want to try and do is you'd have to find a way to direct the image the light in such a way so that it looks like the two lenses are next to each other. So you might have to use prisms and mirrors and a really really elaborate camera by camera rig Uh. These things are are bulky. They make shooting much more difficult. So shooting in three D is a difficult and expensive process. Yes, you know, you're either going to need specialized equipment so that's gonna cost more, like you said before, or you're going to need twice the equipment that you normally would need because you're gonna need, you know, two cameras instead of just one for every single kind of camera shot that you're going to be doing uh, and you're gonna need specialized rigging or mirrors or whatever, and those all have to be set up just right, because if you have a mirror that's not aligned properly, you're not going to get that stereoscopic effect. And then, of course there's a further argument you can have. Do you have both cameras shoot in parallel, so in other words, both cameras are facing directly forward, or do you arrange it so that the cameras converge slightly Because our eyes converge, true, so if you want to have the cameras converge, you have to set that up. And it's a really exacting, precise process, and if you get it wrong, the effect is going to be ruined. So shooting in three D is really complicated and really expensive. There are those who will argue that it's the only way to get three D, right, Yeah, And the thing is really when when you get right down to it, there's nothing inexpensive about three D because the conversion process is also very expensive. Yeah, it can be. Up to the general rule of thumb in the industry for converting a two D film into three D is one hundred thousand dollars per screen running time. So yeah, a hundred and twenty minute movie is gonna cost a hundred thousand dollars times a hundred and twenty and so that's yeah. You start you start adding up and you're like, wow, that's really expensive. It's still cheaper than shooting it all in three D, assuming that you again that you're shooting live action. Well, because again c g I, we've already mentioned that you could just create a a virtual camera and get that effect all on its own. So c g I is easy. Comparatively speaking, It's still gonna take a lot of time. It's gonna take up a lot of hard drive space, and it's not like, you know, it's not like it's a walk in the park. But compared to the problems you face from doing live action, it's it's fairly simple. But let's talk a little bit about the conversion process of two D to three D. Okay, Yeah, I was actually gonna to uh mentioned, especially to your point about how much it costs um the company that did the conversion for Alice in Wonderland, as that company called in three and uh, it can charge. It charges something along the lines of fifty thousand two hundred thousand dollars per minute of time needed to do that. So you think about that in terms of you know, per screen, you're thinking this is really not cheap. Yeah, yeah, I mean you can. I guess you do it once for a master and then you run copies. But at any rate, the uh, yeah, it's expensive and the processes is complicated because what you have to do is, let's say you've got someone gives you a film and by the way, you can do this yourself. I'll tell you at the end of the podcast about a program that will allow you to convert two D movies into three D movies UM using some some open source software. It's pretty cool stuff. It takes a lot of time and it takes a lot of processing power. So if you've got an older computer, this is probably not something you want to try because unless you don't you know, need your computer for three or four weeks um. But converting two D to three D, the first thing you do is you've got this flat image because you know it wasn't filmed in three D, so you have to divide that image into a series of layers, and it's generally between two to eight layers Okay, two layers would be the bare minimum because of course, you know, you need to have that those two layers to create that that sense of depth, and really the number of layers you have per frame depends upon how much stuff is on screen at that time. Yeah, that makes sense. So there was a great example, uh I read about this uh on on slate. Actually there's a great example of talking about a guy standing in front of a brick wall. That might just be two layers that you create there, or two or three. And so once you've figured out what the layers are, next an artist has to go in an outline the object that is, you know, that's going to be at a specific depth. Um, So every single object in the image has to be outlined so that the computer program that you're going to run this through will be able to to calculate what depth each image needs to be in. And then you kind of turn every single image that's on that or every single object that's in that image rather into kind of a topographical map that makes yeah. Yeah, so this is what's telling the computer which parts of that image are should be closer to the eye of the viewer. Because of course, in the three dimensional objects some bits are going to be closer to you than others. So let's say that you're looking at an airplane head on, the nose of the airplane is going to be closer to you than the wings of the airplane, right, So you need to make sure that you you design this topographical map so that the computer realizes, oh, the nose is the front, that's what that's what needs to be closest to the eye. So we're gonna shift that this much for the two images, whereas the wing is further back, we're going to shift that a different distance to create the proper illusion of depths. You have to do this frame by frame, yes, And it's that's why it gets really expensive because it it's a process that requires both manual work and computer programs. It's it's not something that you can just you know, you can't just chunk a two D movie into a what you can, but it doesn't necessarily work. You can't just chunk a two D move into a computer program and expect a great three D film to come out. Now. It's it's it's got to be done slowly and carefully, which is probably why it's so expensive. Um, the the inn three process UH starts with their previous pre visualization or previous program and then they actually use a technique they call dimensionalization, which well, okay, it's pretty self descriptive, but um, during the process they get the directors involved, and what they'll do is they basically can control the depth, shape, and perspective of different objects to tailor the image what's there now, to the screen size that it's going to be shown on, and and to give people, you know, for example, IMAX versus a regular size, regular ish sized movie screen. Not like there's anything that's particularly regular about that, um, but yeah, I mean it's they have control over over that. And maybe one scene doesn't need so much three dimensionalization to make it a peer three D and another requires more. So they go in and scene by scene, frame by frame, they have an opportunity to take control of that. UM. They actually have a soft particular software package that they use, their own homegrown stuff called Intrigue UM. But yeah, I mean it allows them to stay consistent shot to shot, and then they go through a depth grading process that you know, it allows them to do the screen size things, so they can have control over everything. And that's just another reason why it takes so long. But the studios that do this um uh in three and there's another one called Prime Focus that's based in Mumbai. They're the ones who did Clash the Titans, by the way, cost about four point five million dollars according to the Hollywood Reporter. I read an article by A Carol and Giardina, and so, I mean, they all have their own proprietary way and they sort of tell you what's going on, but they don't really get into, if you will, in depth on the matter. But let's talk about some of the problems of converting two D to three D, because there are some quite a few, uh, and there are directors out there, James Cameron among them, who are adamant that this approach is flawed and results in bad movies, or at least technically bad movies. Not necessarily that you know, the script is bad or whatever, but technically it is. Visually. Visually yes it is. It is an inferior product. And Cameron will argue that shooting in three D is really the only way to go right now because our conversion process just isn't good enough. And some of that is understandable because some movies have been converted to three D. Were never intended to be in three D in the first place. But actually he uh, it's kind of ironic in a way because he's partially to uh to blame, not blame, but he's he's partially the reason why everybody is rushing to make three D movies right now because the successive Avatar. Well yeah, I mean when you think about it, that makes it makes perfect sense from Hollywood's perspective, because shooting and releasing a three D film means you can charge more, and it's it's capitalizing on the three D craze right right. Everybody's excited about it, so they wanted so it's do another one. It's easier to make a lot of money because you don't have to sell as many tickets to make as much to make a huge box office. But as well as the fact that it's cashing in on a craze. Uh So, some of the problems with converting two D to three D is is if it wasn't shot meant if it wasn't meant for three D, you may not be getting that. You know, the three D effects that you see may not be that that good. The sense of depth may not really be there because it wasn't intended to be there, that wasn't part of the original vision. Another problem is that sometimes if the if the conversion process is a poor one, and sometimes it is, you end up with what looks like a bunch of cardboard cutouts that are at different in depths. So there is a sense of depth, but there's not a sense of three dimensions. And I've seen this happen with a lot of software that converts two D photos to three D photos in real time, and it looks like, yeah, it looks like, hey, that's not Bill, that's a cardboard cut out a bill. But the cardboard cut out a Bill is closer to the camera than the cardboard cutout of Sarah. It's not at all convincing, and it's actually distracting. That guy always left me a little flat to begin with. Ha ha, such a two dimensional character. Uh. The Another problem is that these films are shot. The two D films may be shot with a certain idea of what the level of light needs to be. Well, when you converted to three D, one of the problems is that if you're using the polarized lenses, that means that the image you're gonna see is already going to be a little darker than what was necessarily intended originally, so you end up with scenes that are darker than the director had intended. This was a big problem, one of many for Avatar The Last Airbender. There were scenes or shot at night that you could not you couldn't tell what was going on because by the time you had the glasses on, it made the shots so dark that you couldn't see anything. Right. Um, now I'm going to wrap this up really quickly. We've pretty much covered how this works. Yeah, I did mention that I was going to talk about how you could convert your own like convert two D movies to three D movies. Sure, there's Uh, there's this great program called avicynthe A v I S y n t H and it's it's free, you can get This is actually kind of a codec more than anything else. So, uh, it's which means it plugs into U to something like Windows Media Player and allows you to read files that have been encoded with right. Right, it's not it's not its own it doesn't have its own user interface. It's not like you would run this program and something would pop up. Um, I got this, by the way from maximum pc so if you want, did you Yeah, it's an article by Alex Castle at maximum pc UM. The article title is how to upgrade your two D movies to three D, So if you want to look into it in detail, I recommend checking out that article. But in general, what does is it provides you a uh so the ability to to create three D films. You have to grab some code UH and the article tells you where to go to get the code. It's from a three D vision blog. And when you put this code in, you can actually convert a two D film into three D. It will create two sets of images. UH. It's a designed to work with Nvidia's three D system, so you need the Nvidia UH graphics card and a Navidia glasses and or if it leads to work. But it also has a setting where you can switch it to anaglyph if you want to, so you wouldn't in that case if you just switch it to anaglyph, you just need the anaglyph glasses in order to view it. But keep in mind that when you're viewing stuff with anaglyph glasses, that means that the color is going to seem a little off. It's not going to be as vibrant again. Um, so there are some issues. And just like we were talking about with the three D conversion thing, if you're using polarized glasses or really it's the act of shutter glasses, it may be a little darker than what the movie was originally intended to be, so you may have to adjust your brightness settings in order to be able to see everything properly, and that may affect the quality of the film. But yeah, check that out if you are interested in doing this yourself, Remember that it's going to take a lot of processing power and a lot of hard drive space if you want to save these, and they actually go into another open source program that will allow you to save the films. Because avicynthe is really a real time conversion thing. It's not designed to save the movie that you've converted. It's just designed to to kind of do the conversion on the fly. If you want to save it, you're gonna need to use a separate set of programs and codex. But maximum PC spells that all out, and the three D Vision blog also does so if you're interested, check that out. Okay, all right. That sums up our movie making Technology three D podcast spectacular. I hope you guys enjoyed it. 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