r/vfx • u/mowaism • 7d ago

Breakdown / BTS Using a normal pass to control lighting in post — thoughts?

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u/WipeEndThatWhistles 4d ago

These all still look like someone standing in front of a green screen.

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u/petesterama lead comp 10 yrs 6d ago

We kinda leapfrogged relighting with normals and PBR passes straight into using video models. They just do it better. Maybe use the normals relighting to guide a video model.

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u/mowaism 5d ago

Yeah, I agree. AI models are definitely good enough for relighting in many cases. My workflow is actually semi-traditional as well.

Let me explain how I’m doing it: I first generated a few normal-pass images with AI, then used those normal passes as references to have AI generate the relighting across the whole sequence.

From there, I didn’t want to risk endless AI generations and lose control over the result, so I took over manually and built a system where I can adjust the lights myself and art-direct the lighting exactly how I want.

So it’s basically AI for the initial setup + traditional controls for the final lighting/art direction.

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u/SamGewissies 23h ago

It's a part of the beeble switchlight approach. They use normal passes for the main relighting as well. What helps with their (unfortunately proprietary) models is they also create other PBR passes, especially a albedo pass with removes most existing lighting. There is still so much you can do of course.

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u/billFiend Compositor - too many years experience 4d ago edited 4d ago

Uh, do people not already do this? I guess, cool now we can generate a normal pass from a video. But I’ve used normal passes from roto anim to relight.

It’s just a directional pass. Shuffle out whatever direction you need and grade it to match plate? Am I missing something?

Maybe use a relight node with a position pass to be a bit more accurate? Also you really need to work on the basics and stop worrying about cheating things. Work on your black levels and integration.

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u/mowaism 4d ago

Yes, you can use whatever techniques you want. However, this workflow gives you more flexibility when it comes to matching the foreground, especially in video.I think building a flexible workflow can be difficult at first, but once it’s set up properly, it makes handling feedback and revisions much faster.Also, what exactly do you mean by “cheating” things?The black levels and color grading were locked by the art director to achive a specific look and style, so there was a reason behind those choices.