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Re-creating Disney's sodium vapor process [video]

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Re: Re-creating Disney's sodium vapor process [video]

#51

Post by niccl »

laserbeam wrote: post #48
YoshiRulz wrote: post #39

Earlier quoted context omitted.

This was addressed at the end of the video: The main points are that it can't be used outside, or when the shot includes the subjects' legs/feet (as the ground would need to be an amber-screen as well), and on top of that, it requires a certain level of setup which some shoots can't afford.

I don't think I've ever seen green screen used outside either. I think you can kinda use it outside... But any random cloud passing by would destroy your morale in the editing room if you're keying against green screen. Also lighting conditions change during a day and you'd have to be aware of that when keying. Not fun.

Lord of The Rings used some huge external green/blue screens. One I know of was the scene in Return of the King where there's a dead oliphaunt and, IIRC, Eowyn fighting the Witch King. But there were lots of others.

Re: Re-creating Disney's sodium vapor process [video]

#52

Post by ikiris »

modeless wrote: post #32
ikiris wrote: post #19

Earlier quoted context omitted.

Because you want color bands that you control, not that are naturally emitted.

Near infrared isn't naturally emitted by room temperature objects. You're thinking of far infrared.

I didn't say room temperature objects. I said naturally emitted. Trying to have lights and other objects involved in film production that don't have emission spectra inside the mask range for near infrared would be a lot of effort compared to just... not having it be a problem with things that are easily attained with cheap materials like sodium narrowband.

Re: Re-creating Disney's sodium vapor process [video]

#53

Post by modeless »

ikiris wrote: post #52
modeless wrote: post #32

Earlier quoted context omitted.

Near infrared isn't naturally emitted by room temperature objects. You're thinking of far infrared.

I didn't say room temperature objects. I said naturally emitted. Trying to have lights and other objects involved in film production that don't have emission spectra inside the mask range for near infrared would be a lot of effort compared to just... not having it be a problem with things that are easily attained with cheap materials like sodium narrowband.

By that definition the sodium wavelength is naturally emitted too. The sodium vapor process as implemented in the video requires special lights that don't emit the sodium wavelength. It's actually much harder to do that (and it affects color reproduction too) than to block some infrared from existing lights. Infrared blocking film and filters are readily available and cheap. They don't need to be fancy narrowband notch filters like a sodium wavelength filter would have to be.

Now that I think about it, Disney must have done something pretty special for the lighting in the foreground in their version of the process. They didn't have single wavelength LEDs back then. I wonder how they did it?

Re: Re-creating Disney's sodium vapor process [video]

#54

Post by sixothree »

jmpman wrote: post #24

I’ve been doing something similar using “cheap” Chinese band notch filters. Had no idea about this Disney process. Also using this for AI training purposes. It’s amazing what you can buy on Alibaba, fully custom frequencies.

After you using sodium vapor out a different light source?

Re: Re-creating Disney's sodium vapor process [video]

#55

Post by Glyptodon »

laserbeam wrote: post #47
largbae wrote: post #15

Earlier quoted context omitted.

Does the magic color need to be within the frequency range that the camera and video format can record?

You want the 2 cameras you are recording with to be near identical. If the lens is different (for example) then the mask might be distorted and would not line up with the colored image. Building 2 nigh identical cameras, but one with a sensor outside of the frequency range of the other, is probably a very expensive custom job.

If you have the prism for it and you just need a lens mount attachment at sensor distance from the prism and two reverse mounts on the other side of it to mount mirrorless cameras on (assuming light comes out of the prism straight or if you can just split the distance between each side of the prism -- note I have no idea about this) it doesn't seem that expensive - buy a couple mirrorless cameras, get yourself a cube with the mounts, and get going with one lens, no?

It seems like the cube with mounts is the most expensive part, and there's no way it can cost more than one of your cameras, let alone the lens, right?

Re: Re-creating Disney's sodium vapor process [video]

#56

Post by rendall »

kadoban wrote: post #3

Very interesting stuff. I'm curious if this means anything in terms of good vs perfect technology or what tech wins out in practice. This process seems just plain better than green-screen, so why did it lose out? Is is just that green screen is good enough? Was it too hard to do this sodium vapor process with random cameras back in the day? Are sodium vapor lights bad enough in some way that practically it lost out?

> so why did it lose out?

The video suggests that it was difficult to replicate and extremely expensive.

Re: Re-creating Disney's sodium vapor process [video]

#57

Post by wiml »

modeless wrote: post #10

Hmm, why don't people do this with near infrared? It would allow using full spectrum lighting, and would be easier to selectively filter. I'm guessing the answer is "they do, it's just uncommon and you haven't heard about it"

From what I've read in old books on SFX, they did, and near-UV as well.

My guess though is that using a visible wavelength makes it easier to set up the lighting and ensure it's even and so on (remember, this was before electronic technologies that would make it possible to live-preview the result). Also, sodium lights and sodium band filters had other uses in industry so they might have been more available than NIR/NUV equivalents.

Re: Re-creating Disney's sodium vapor process [video]

#58

Post by jlarcombe »

bcraven wrote: post #40
pushedx wrote: post #9

Very very cool, mindblowing actually, seems legitimately useful. There have been a few art installations over the years that use these lights: https://www.youtube.com/watch?v=hd077pa-5CI For a second I thought that the video was from this channel, which also does experimental cinematography stuff: https://www.youtube.com/watch?v=-4uzyhbDFas

After seeing the Olafur Eliasson retrospective at the Tate Modern a few years ago I tracked down the components to build my own low pressure sodium vapour light. It's so weird, as those people say, so see things coloured... yet monochrome.

I rather miss them in the streets. It's only been, what, ten years or so since they've been replacing most of them with white LEDs round my way, but it's almost hard to remember that everything was yellow whenever you went out in the dark! Especially amazing atmosphere when it snowed...

Re: Re-creating Disney's sodium vapor process [video]

#59

Post by wokwokwok »

modeless wrote: post #44
wokwokwok wrote: post #42

Earlier quoted context omitted.

Huh, my bad, I thought thermal sources (ie. like random hot stuff, not glowing hot stuff) emitted a wide band of frequencies including near-IR, but fair enough. You'd still get it from any sort of incandescent light source right? (same as a sodium lamp) > but with important advantages What's the benefit over using any other single frequency visible light? Even if the atmosphere absorbs most of a particular band, if a…

The advantages I stated were > It would allow using full spectrum lighting, and would be easier to selectively filter. Making a broad spectrum IR filter is far easier than a notch filter for a single visible wavelength. In general it's harder to make more selective filters and an IR filter can be much less selective because the IR band is so large and far away from any visible light. Also the infrared version would a…

The whole point of this technique is that you have that sharp frequency band and a crystal / filter that splits like band out.

You're basically proposing something completely different here.

So... while I agree you could do something as you describe, and I'd be interested to see the results of it, I'm not sure what the results would be like.

> The advantages I stated were

>> It would allow using full spectrum lighting, and would be easier to selectively filter.

All I can say is the CC results in that video were pretty great, despite the obvious caveats, compared to green-screen.

If you (or anyone) can build on it to do better, people will be interested in it; but there's obviously a difference between us idly speculating on how/if it might work, and this, where they've actually done it and shown that it does work.

> "they do, it's just uncommon and you haven't heard about it"

I've never heard of it being done.

If anyone has, please post a link or something.

Re: Re-creating Disney's sodium vapor process [video]

#60

Post by modeless »

wokwokwok wrote: post #59
modeless wrote: post #44

Earlier quoted context omitted.

The advantages I stated were > It would allow using full spectrum lighting, and would be easier to selectively filter. Making a broad spectrum IR filter is far easier than a notch filter for a single visible wavelength. In general it's harder to make more selective filters and an IR filter can be much less selective because the IR band is so large and far away from any visible light. Also the infrared version would a…

The whole point of this technique is that you have that sharp frequency band and a crystal / filter that splits like band out. You're basically proposing something completely different here. So... while I agree you could do something as you describe, and I'd be interested to see the results of it, I'm not sure what the results would be like. > The advantages I stated were >> It would allow using full spectrum lightin…

No, the point of the technique is you have a frequency band that you can isolate and use in the background and not in the foreground. Using IR instead of visible as your isolated band makes the isolation easier and cheaper with fewer artifacts and limitations. It's still a very similar process otherwise.

Yes, Corridor's results were great. Fewer limitations would make the process even better!

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