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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]

#31

Post by magicalhippo »

modeless wrote: post #16
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?

Most camera sensors need a filter to block infrared light because they are sensitive to it. Remove the filter and replace it with an infrared pass filter, and you've got an infrared camera. It may not be as sensitive as in visible wavelengths but you can use brighter infrared lights to compensate if necessary. This sodium vapor process already uses two cameras so it would work the same way. It seems possible to produ…

The sensors should be sensitive[1] well into the near-IR, and there are people in the astrophotography community which can service digital cameras to remove the IR-cut filter, these[2] for example.

Another alternative I was thinking about is just to use one of those monochrome astrophotography cameras, something along the lines of this[3]. The monochrome version doesn't have the IR-cut filter and sensitivity is pretty ok down into near-IR.

edit: The IMX492 sensor in that one has a 40% response at 850nm, and 850nm IR diodes are plentiful and shouldn't emit[4] much at all below the 700nm of the IR-cut filter the color camera should have.

Not sure how mixing sensor sizes and such would affect things, or if it's better/easier to just run two of the same camera.

[1]: https://s1-dl.theimagingsource.com/api/2.5/packages/publicat...

[2]: https://www.lifepixel.com/

[3]: https://www.zwoastro.com/product/asi294mm-mc/

[4]: https://lumileds.com/wp-content/uploads/files/DS191-luxeon-i...

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

#32

Post by modeless »

ikiris wrote: post #19
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"

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.

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

#33

Post by kadoban »

astrodust wrote: post #22
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.

Incentive is one thing, budget is another. Keep in mind stuff gets lost all the time, even really important things like nuclear weapon components like https://en.wikipedia.org/wiki/Fogbank

Fair. But looking at that story (very interesting btw, thanks), they did recreate it. So incentive does mean a lot when $$ is also available, which I'd suspect it is in movies.

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

#34

Post by krasin »

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.

I would be interested in some links!

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

#36

Post by wbl »

kadoban wrote: post #5
buck746 wrote: post #4

Earlier quoted context omitted.

It lost because there were only 3 prisms made. It also required a lot more lot as running thru an optical splitter means at least half of your light was lost, it's not a big issue today. Modern cameras are insanely more sensitive than film was at the time. Alfred Hitchcock used this on "The Birds". In the YouTube video they got a great result even with a smaller studio than would have been used on Mary Poppins. The t…

> 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.

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

#37

Post by hollerith »

hansvm wrote: post #29
hollerith wrote: post #21

Earlier quoted context omitted.

>brighter infrared lights to compensate if necessary I am guessing that that is dangerous to human health because infrared fails to elicit the flinch reaction that too-strong visible light does.

Near-infrared penetrates very well. The same intensity is much safer, up till you get to the levels of radiation that are dangerous regardless of how they're distributed in your tissues. That's one of the things that makes it suitable for thermal nano cancer therapies. You (1) Create a nanoparticle with a gold core of the right size that it excites when exposed to near-infrared radiation (the far end of "near" is ide…

>Near-infrared penetrates very well. The same intensity is much safer

Glowing-hot steel produces enough IR that the workers that work with it have 7 times the rate of cataracts as the general population.

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

#38

Post by kibibu »

ChrisClark wrote: post #30
footlose_3815 wrote: post #18

Earlier quoted context omitted.

[flagged]

He's been trying to recreate this for years, I can understand why he's so excited to do it and that it works so perfectly.

The actual cleverness was from Paul Debevec, who has done incredible things for the Vfx industry over his career.

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

#39

Post by YoshiRulz »

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?

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.

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

#40

Post by bcraven »

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.

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