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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]

#61

Post by rerdavies »

jiggawatts wrote: post #41

The original beamsplitter cube isn't some exotic custom device that would cost tens of thousands to make. It's just a dichroic beamsplitter, which is a standard optical element available from online sellers. Variants of these are commonly sued in scientific experiments, optical devices, etc... Here's one for under $300: https://www.meetoptics.com/beamsplitters/plate/longpass-dich... Just search for: "589 nm beamsplit…

Presumably, the exotic part of the beamsplitter is that the dichroic filter must be a bandpass filter with a very narrow passband around 596nm. Yours is a high-pass filter, which wouldn't work for this application.

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

#62

Post by lqet »

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

Yes, extremely impressive. "Mary Poppins" rightfully received an Oscar for best visual effects.

I am continuously amazed at the level of innovation done at the Disney studios back when Walt Disney was still alive. Rewatching Snow White with my daughter a few months ago, I was flabbergasted by the animation quality, even when compared to animation movies made decades later. Just look at these water scenes:

https://youtu.be/54QeNL5ih6A?si=dOdrRrISu8f4I96G&t=95

https://youtu.be/khmrr7-W6BA?si=whn5mvuL9x95JP1l&t=70

This was in 1937! Compare these scenes to this Paramount animation clip (also featuring Snow White), which was finished just 4 years earlier: https://www.youtube.com/watch?v=cKOSJ5AAwfc

The multiplane camera [0] is also ingenious and is imho the single biggest reason why Disney could produce animation movies that looked "cinematic". I read somewhere that they re-used it for "The Little Mermaid" in the 80ies, and nobody really remembered how it worked anymore.

Disney also developed Xerox animation [1], which is cheaper than traditional animation, but which gave 101 Dalmatians a very nice "sketchy", artsy look .

[0] https://en.wikipedia.org/wiki/Multiplane_camera

[1] https://www.smithsonianmag.com/innovation/how-one-hundred-an...

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

#63

Post by ginko »

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"

Apart from what others have said, you'll run into problems with chromatic lens aberrations the further your "key" wavelength is outside of the visible spectrum so your two images might start to mismatch too much.

I know in IR still photography you're supposed to add a focus offset marked on your lens to adjust for that. A regular achromatic lens quickly fails outside of the wavelength range it was designed for[1].

[1] https://en.wikipedia.org/wiki/Chromatic_aberration#Minimizat...

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

#64

Post by beAbU »

lqet wrote: post #62
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

Yes, extremely impressive. "Mary Poppins" rightfully received an Oscar for best visual effects. I am continuously amazed at the level of innovation done at the Disney studios back when Walt Disney was still alive. Rewatching Snow White with my daughter a few months ago, I was flabbergasted by the animation quality, even when compared to animation movies made decades later. Just look at these water scenes: https://you…

Re the animation quality: I wonder if Disney didn't create a lot of their later animation by rotoscoping over live-action recordings? The quality of the animation and the realism of the characters' movements in those examples you posted definitely allude to this.

Disney was known to recycle some of their animations in older movies [1], so this could be because they have a source live action recording somewhere that they rotoscoped over more than once for different productions. Also note the different backgrounds with different characters that move - excellent example of the multiplane camera in action. In the foreground they have a "recycled" animation, in the background they can then put something else in, and record it all in one go with their special camera.

1 - https://www.youtube.com/watch?v=vd09WdOgOeg

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

#65

Post by namibj »

cladopa wrote: post #12
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? Is is just that green screen is good enough? It looks that the problem was manufacturing the prism, as simple as that. Today you can use unusual wavelength LEDs without phosphorous to do the same thing probably way cheaper.

No, LEDs are far wider than low pressure sodium, which is two about 0.1nm wide (thermal broadening, IIUC basically Doppler effect between the emitting particle and the surrounding world/containment vessel) lines 0.56nm apart. See https://lambdasys.com/uploads/LLE-2.pdf for a measured spectrum that's not as coarse as the one on en-wiki where both lines are blurred together.

LEDs are 10~50nm, untuned laser diodes 1~10nm. It is my understanding that it's easy to make a filter for the camera that very selectively targets this line pair, though it may entail mild optical complications as a sub-nm pass/reject bandwidth detunes from sideways angles, so lenses may need to collimate the light first before feeding the filter, and de-collimate again after.

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

#66

Post by namibj »

wbl wrote: post #36
kadoban wrote: post #5

Earlier quoted context omitted.

> It lost because there were only 3 prisms made. But it seems so much better that that shouldn't have been a blocker. Like optics isn't magic, and knowing that someone did it before should be enough incentive? Not like movies are a small or poor industry.

Today we could use a dichoric coating but back then I think fabrication was much harder.

Well, the technology for them is far from recent, the process control and chamber geometry design to allow the needed precision and uniform-ness at the throughout needed to not be extremely expensive, however, required cheap microprocessors for a good decade to develop the required skills in control engineers to then actually go and make a machine like this. And the computers suitable we're still triple-digits in the 80's, so this only really started to deploy to factories ~25 years ago.

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

#67

Post by ctrw »

modeless wrote: post #60
wokwokwok wrote: post #59

Earlier quoted context omitted.

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!

Near ir LEDs are also cheap and easy to power, with its what's in remote controls. Low pressure sodium lights aren't. I remember using them in postgrad labs and it wasn't fun.

Alternatively you could use a solid state laser or narrow band LEDs if you need the band to isolate to be in the visible spectrum too.

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

#68

Post by eurekin »

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"

Maybe... it would get too hot?

EDIT: actually, since it's outside of the visible spectrum, typical lens design correcting longitudinal chromatic aberration and doing the spherical to rectlinear projection simply might be off, resulting in soft edged and general artifacts unwanted in a clean mask

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

#69

Post by lqet »

beAbU wrote: post #64
lqet wrote: post #62

Earlier quoted context omitted.

Yes, extremely impressive. "Mary Poppins" rightfully received an Oscar for best visual effects. I am continuously amazed at the level of innovation done at the Disney studios back when Walt Disney was still alive. Rewatching Snow White with my daughter a few months ago, I was flabbergasted by the animation quality, even when compared to animation movies made decades later. Just look at these water scenes: https://you…

Re the animation quality: I wonder if Disney didn't create a lot of their later animation by rotoscoping over live-action recordings? The quality of the animation and the realism of the characters' movements in those examples you posted definitely allude to this. Disney was known to recycle some of their animations in older movies [1], so this could be because they have a source live action recording somewhere that t…

I found this interesting paragraph on Wikipedia:

> Very few of the animators at the Disney studio had had artistic training (most had been newspaper cartoonists); among these few was Grim Natwick, who had trained in Europe. The animator's success in designing and animating Betty Boop for Fleischer Studios showed an understanding of human female anatomy and, when Walt Disney hired Natwick, he was given female characters to animate almost exclusively. Attempts to animate Persephone, the female lead of The Goddess of Spring, had proved largely unsuccessful; Natwick's animation of the heroine in Cookie Carnival showed greater promise, and the animator was eventually given the task of animating Snow White herself. Though live action footage of Snow White, the Prince and the Queen was shot as reference for the animators, the artists' animators disapproved of rotoscoping, considering it to hinder the production of effective caricature. Nevertheless, all of the above-mentioned characters were fully rotoscoped and utilized by their respective artists, some more, some less.[98] Despite Graham and Natwick's objections, however, some scenes of Snow White and the Prince were directly traced from the live-action footage.

https://en.wikipedia.org/wiki/Snow_White_and_the_Seven_Dwarf...

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

#70

Post by eurekin »

rerdavies wrote: post #61
jiggawatts wrote: post #41

The original beamsplitter cube isn't some exotic custom device that would cost tens of thousands to make. It's just a dichroic beamsplitter, which is a standard optical element available from online sellers. Variants of these are commonly sued in scientific experiments, optical devices, etc... Here's one for under $300: https://www.meetoptics.com/beamsplitters/plate/longpass-dich... Just search for: "589 nm beamsplit…

Presumably, the exotic part of the beamsplitter is that the dichroic filter must be a bandpass filter with a very narrow passband around 596nm. Yours is a high-pass filter, which wouldn't work for this application.

So, a second beamsplitter with low-pass filter wouldn't cut it?
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