do you ever feel like visual effects in old movies were better what if I told you that wasn't just Nostalgia speaking back in the 1960s Disney invented a technology that was in many ways superior to the green screen but that Tech has long since been forgotten and what if I told you that we found a way to recreate [Music] it being able to layer one moving image over another is the fundamental building block of visual effects every single crazy effect shot from every movie you love relies on this basic core technique and the primary way we do that is with green screen or blue screen but there are lots of problems with green screen even in this modern era you can't film blurry or transparent things you can't wear clothes that are the same color as the screen and the spill of the color often times ruins footage if I want to make a movie about a clown wearing all the colors of the rainbow getting married on Mars I can't that bothers me if I could get my hands on an invention that didn't have any of these issues it would be like a filmm superpower it would be like magic do you really think so what's special about that app it's transparent it's arent transparent I thought the stuff I was seeing on screen was impossible they're keying a veil they're keying salt smoke they're even wearing blue and green clothes this movie from 1964 broke every rule of chroma and they did it all without computers so how do they do it to explain the science behind the magic we are joined by Dr Paul debevic the sodium vapor process instead of a blue screen or a green screen they used what was sometimes called a yellow screen there a very specific spectrum of yellow made from a low press sodium vapor light that puts out one wavelength of light at 589 NM because it's just one wavelength and because of how drro filters work you can actually block just that one wavelength or let just that one wavelength go through so the magic of the sodium vapor process is they used a beam splitter prison so that the light that comes through the lens gets split onto two strips of film at the same time the sodium vapor wavelength of 589 NM reflects out this way and all the rest of the spectrum goes through and can expose a color image of the actor and that's exactly what you need to get your map what's kind of magical about it is that you can block that one wavelength of yellow without messing up all of the other colors in that scene there's no mat lines he's motion bluring he's dancing around the compositing is impeccable yeah it's perfect you couldn't have gotten such great blur over the alpha Channel with a green screen or a blue screen seems too good to be true why are we not still using this technology today yeah really what gives because they were never able to replicate prism what I've read that Disney was only able to produce one prism is that true they had to join two pieces of glass and then have layers of material with different indices of refraction it's a very custom job and it would probably cost tens of thousands of dollars at a minimum apparently there were three of these ever made and also we don't know where any of these prisms are today and that means I'm never going to get to answer this Burning question I have is sodium vapor better than Green Screen the science the physics they all tell me it is but because the prisms have been lost the time I'm never going to get to realize my dream of a clown getting married on Mars and then one day I got a message from Paul debevic he had done what I thought was impossible he had recreated Disney's Magic prism and he needed somebody to test it out this will be the first test of the sodium vapor process in over 30 years well I guess this is like our hello world of sodium vapor matting we've got our color image and our sodium vapor image there there it is look at that that's the idea it's working the first thing you need are some sodium vapor lights so thankfully they still make the bulbs eventually after we've had these on for 10 minutes they'll start glowing that color I think it's working and then we've got a couple of LED lights here that are going to illuminate the actor so favor mats woohoo hey pretty sweet how is this working how did Paul debevic manage to resurrect Disney's lost prism well with a deep understanding of the science of light and a little bit of C ity I'll do a beam splitter but I'll just do a regular beam sweit like this beam splitter and then we'll filter the light after it comes out of the prism Paul recreated the physics of the sodium Vaper process but he did it with all off-the-shelf components instead of a custom beam splitter he used two filters and instead of two strips of film he just used two cameras yeah if you ever think your rigs are janky they're all janky for the first time ever my dreams are within my grasp want to know what's within your grasp a beautifully designed website thanks to our sponsor Squarespace whether you're an artist an entrepreneur or dreaming 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find out what I'm going to do with all these hard Tokey clothes Paul I would like to tell you about this character every time I approach a production company with it they're like no can't do it it's impossible okay and it's a story about a clown that's trying to get married you look so dumb me what look I've heard big things about this magic Crystal okay but this is ridiculous that's impossible to key look at that I hate to break it you but this video is going to be a disappointment JC H feel free to come on out it's my wedding day oh my God that would be difficult to key wouldn't it it would I forgot to mention that uh the Clown's getting married on Mars hence the need to replace the background oh of course yeah I think this is going to be fantastic now I suppose we should uh clean up the lighting yeah kill all of the Full Spectrum Lighting we need that one covered yeah I need to cover one of the skylights so that we don't have all this like daylight spill coming in it's and my dress is like marily been rowing right now keep this side down it's the best the clown can do so as you can see right now we're spending a lot of time getting these flags up because what we don't want to have happen is we don't want the sodium vapor light to be hitting JC at all cuz then it's going to be basically turning her transparent so this is a spectral light meter it tells you the spectrum of the light for example this light here that shows its LED light that's made out of red green and blue LEDs to make the color white and I can also take it and put in front of the sodium vapor lights there is our sodium vapor Spike at 589 nanm so let's see if there's any sodium vapor light hitting our subject mostly good but if I look closely here I can see a tiny little blip see that tiny little blip of sodium vapor yeah science we're very close but we're getting a little bit of side spill on her and we're just cleaning that up here if we're the first ones to do this in like 30 years I want to do it right you know it went down nice that should be better looks like we almost have a perfect mat I guess the only thing left to do is to shoot it maybe we should shoot cool go ahead and roll the cameras here we are in Mars the clown is looking for the groom uh-oh there's aliens behind you maybe turn around wave at the aliens I want get one shot of myself as well wearing my green hoodie which I refused to take off and hopefully the sodium vapor process lets us do something Nico I want to see you do some headbanging I want you to throw that head around I think we got it that would be the hardest green screen shot that would be so hard to do on a green screen and cut dude this is going to be as successful as Mary Poppins oh my god [Music] wow Paul's research has been super influential on me to get to work with him on an experiment is super super cool I hope this works all right let's take a look at what we got here's what our color footage looks like and if I look at the sodium vapor shot wow it looks pretty good let's see what happens if I take that and turn it into a black and white transparency mask wow this should work really well but before I try pulling a transparency key here I need to also try this with green screen to do a true comparison to know if this is better I'm using all the tricks for perfect green screen that I've acquired over the years lights with a hint of green on them lights on Jordan with a hint of magenta to cancel out the green spill from the green screen I'm going to do my best to light this green screen and shoot it as good as I can all right hi you're on Mars wave to us the audience so we all know that sodium Vapor should give scientifically better results but green screen tools have had years and years and years to mature I can start pulling in the thickness of that mat but while the dress starts to come back the veil now has these ugly lines I can try to you know close the holes in the dress using a different tool here but it patches up the holes in the veil there's just no way to handle the range of greens here and for green screen tools to know what we want to keep and what we don't want to keep oh no yuck destroyed actually not bad bad be honest did you do your best with the key I did the issue is is I can't get the transparency of the veil and like the slightly off green dress in fact the only way you could do a shot like this is to go in and cut out all these different sections by hand and have a bunch of Patchwork different solutions in the image if the sodium vapor process is superior it won't have any of these issues all right so it's time to try the sodium vapor process to do the composite and see if it works here we have JC and here we have our background right and the way we're going to do this actually mirrors the way they did it on film back in the day the thing is if you just take two pieces of film and you layer them over each other you end up with a double exposure you need something called a hold out mat that leaves a hole for you to Simply add your other image on top so we're going to take our background and we're going to subtract the mat we're going to take our foreground and we're going to subtract everything that isn't the mat now I take our background and our foreground and we simply add them together honestly I'm really excited to see this because it felt like we were doing one of the coolest and most high-tech things we've ever done and I would love for this to pay off here are the results and I'll let you guys be the judge [Music] waa wow that's wild dude it's Mary Poppins this is amazing it's incredible oh no you dog water he's drinking water on M this is my favorite one the water is just such a flex check out the motion blur oh the hands oh wow the motion blur drops the color exposure correctly on the background right there turns it red oh corrected ma oh my God it's so good dude those little tiny hairs on top oh my God and I didn't have to do any work you didn't have to tweak your like white clip black clip no I hate that D spill bias no there's no spill what about your Edge feather edge feather no D spill no messing with gamma of your mat no thresholds no restoring Fringe no cleaning the blacks no cleaning the whites nothing he's turn it on yes turn it on wow good job good job that is amazing po y so I just got the opinion of everybody at Corridor but I need to get the opinion that actually really matters oh wow you're zooming in on it you are not afraid of your mat lines that was clearly exactly what needed to be filmed to show off this technique exactly what about a volume could you use a volume in today's age when you can just go and shoot on a volume with an LED screen is sodium vapor worth pursuing in practice a lot of those in camera back grounds will get replaced so it seems like we're still in a world where we need to be able to cut out backgrounds and put people on new things yeah flexibility in post- production is incredibly valuable one thing that you're noticing is like composing tools are getting better CU they're starting to have a bit of machine learning inside of them machine learning needs training data the question is where do you get all that training data there is no perfect easy compositing technique and I thought this would be a good way to do it so sodium vapor is another one of those essential steps in this progress towards having perfect transparency for compositing and visual effects then absolutely it is the gold standard the yellow standard well Paul thank you once again for joining us here on the corridor Channel if you like these deep dives into classic visual effects technology along with industry experts talking about it you'll definitely love our Abyss video so go check that out and uh yeah thank you I really appreciate it great to see you glad you come mind this was fun this is a great time totally