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It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

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Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#31
post #9

I'm a software engineer that, like the vast majority of you, uses AI/agents in my workflow every day. That being said, I have to admit that it feels a little weird to hear someone who does not write code say that they built something, without even mentioning that they had an agent build it (unless I missed that).

This is interesting. I had the exact opposite reaction.

You don't hear architects get hounded because they say they "built" some building even though it was definitely the guys swinging hammers that built it. But yet, somehow because he didn't artisanally hand-craft the code, he needs to caveat that he didn't actually build it?

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#32
post #24

Earlier quoted context omitted.

I'll do you one better, which requires no special cameras (most have IR filters) nor double cameras or prisms. Shoot the scene in 48 or 96 fps. Sync the set lighting to odd frames. Every odd frame, the set lights are on. Every even frame, set lights are off. For the backing screen, do the reverse. Even frames, the backing screen is on. Odd frames, backing screen is off. There you go. Mask / normal shot / Mask normal…

Surely this makes your actors feel sick? And wouldn’t it make your motion blur look dashed and also cause artifacts at the edge of the mask if there’s a lot of motion?

Incandescent and fluorescent lights already flicker at your AC power frequency. Just gotta be higher than that

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#33
The sad thing about this is the problems encountered during post from the production team saying "fix it post" during the shoot. I've been on set for green screen shoots where the lighting was not done properly. I watched the gaffer walk across the set taking readings from his meter before saying the lighting was good. I flip on the waveform and told him it was not even (which never goes down well when camera dept tells the gaffer it's not right). He put up an argument, went back and took measurements again before repeating it was good. I flipped the screen around and showed him where it was obviously not even. A third set of meter readings and he starts adjust lights. Once the footage was in post, the fx team commented about how easy the keys were because of the even lighting.

The problem is that the vast majority of people on set have no clue what is going on in post. To the point, when the budget is big enough, a post supervisor is present on production days to give input so "fixing it in post" is minimized. When there is no budget, you'll see situations just like in the first 30 seconds of TFA's video. A single lamp lighting the background so you can easily see the light falling off and the shadows from wrinkles where the screen was just pulled out of the bag 10 minutes before shooting. People just don't realize how much light a green screen takes. They also fail to have enough space so they can pull the talent far enough off the wall to avoid the green reflecting back onto the talent's skin.

TL;DR They solved something to make post less expensive because they cut corners during production.

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#34
post #23

There's still a bug: the glass with water does not distort the checker pattern in the background at 24:12.

True, but with visual art there is what is correct and what looks correct. When things are moving and the area small no one is going to notice.

But now that is problem is solved a director will come along and say... I want a scene with a big glass of water and the camera will zoom in on it and will see the monster refracted through the glass.

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#36
post #23

There's still a bug: the glass with water does not distort the checker pattern in the background at 24:12.

You’d have to track it, render it, and comp it in. It’s not ridiculously difficult, but there’s no way that’s going to happen automatically.

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#37
post #9

I'm a software engineer that, like the vast majority of you, uses AI/agents in my workflow every day. That being said, I have to admit that it feels a little weird to hear someone who does not write code say that they built something, without even mentioning that they had an agent build it (unless I missed that).

This is interesting. I had the exact opposite reaction. You don't hear architects get hounded because they say they "built" some building even though it was definitely the guys swinging hammers that built it. But yet, somehow because he didn't artisanally hand-craft the code, he needs to caveat that he didn't actually build it?

Maybe it's a language thing. Architects saying they built something sounds a bit off to me. In my native language, and in everyday language, I don't think people would use "built" like that. I don't know how architects talk with each other, though.

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#38
post #13

Earlier quoted context omitted.

That is far-IR, thermal stuff, Near-IR, 700 nanometer-ish is right below red in human vision. Camera sensors can pick up a little near-IR so they have have a filter to block it. If that filter was removed and a filter to block visable light was used in place you would have a camera that can only see non-visable light. Poorly, the camera was not engineered to operate in this bandwidth, but it might be good enough for…

You can actually dimly perceive near-IR LEDs -- they'll glow slightly red in darkness.

I remember reading some people can perceive some near IR, but mostly that near-IR LEDs actually leak some red themselves due to imperfections in manufacturing or something?

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#39

The sad thing about this is the problems encountered during post from the production team saying "fix it post" during the shoot. I've been on set for green screen shoots where the lighting was not done properly. I watched the gaffer walk across the set taking readings from his meter before saying the lighting was good. I flip on the waveform and told him it was not even (which never goes down well when camera dept te…

I fully agree but I think for them making it possible to cut corners during production is the whole point. Think about it: The choice is between 5 minutes of work plus a one time purchase of a decent GPU and a big room with a complex lighting setup with a post supervisor present. Now, quality of the end result will not be the same, for sure. You and me would opt for the quality setup whenever we can, but many others won't.

Re: It Took Me 30 Years to Solve This VFX Problem – Green Screen Problem [video]

#40
post #23

There's still a bug: the glass with water does not distort the checker pattern in the background at 24:12.

You’d have to track it, render it, and comp it in. It’s not ridiculously difficult, but there’s no way that’s going to happen automatically.

>there’s no way that’s going to happen automatically

They train their model in a pretty straightforward way, it can also be used to capture the distortion as well, just use a non-monochrome (possibly moving) background optimized for this. It's a matter of effort and attention to detail during training (uneven green screen lighting, reflections, etc), not fundamental impossibility

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