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Comment by Laremere | Hacker News Reader

If you think this stuff is neat, there's a neat improvement on this using what are essentially video walls. Replacing the greenscreen removes the problems with green or white, and gives presentors/actors better idea of their space.

Tom Scott did a quiz series showing off the technology, linked to timestamps where he explains things:

https://youtu.be/zV14G-Sxu7M?t=781

https://youtu.be/Odq0ggVVRyM?t=545

https://youtu.be/RDsRFpVp0kk?t=597

https://youtu.be/xIDr5n9UIR4?t=479

See also roughly the same technique being used in the Mandalorian TV show: https://www.youtube.com/watch?v=gUnxzVOs3rk

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Video walls aren't very suitable for this use case actually.

The Mandalorian has very specific prebaked imagery to do what it does where latency isn't a big deal. It also uses post production to clean up.

With the kind of volume space that the BBC have, and the frame rates and sweeping camera moves, they likely can't make use of current LED walls.

They don't have the offline resources to clean up the seams in the wall panels, and they probably can't afford the latency of the walls (with walls you need much lower latency than green screen since there's no temporal room to compensate for rendering latency)

Video walls are suitable and are used. There are no seams between the panels and realtime rendering is fast enough for moving cameras. All camera movements are tracked, a virtual camera at the exact same position renders the image which is then shown on the LED wall. The image outside of the panels will be masked with a seamless transition (biggest obstacle here is video wall brightness vs. studio lights). Delays are adjusted for.

You can see how this works in a very small set here: https://www.youtube.com/watch?v=mhmYawxWfjE

And here you can see how the image moves when the camera moves: https://www.youtube.com/watch?v=6koVH1vmLp4

The combination of the technologies is product of the last 2-3 years, but it is already used around the world and a major benefit is that there is no additional post production needed.

The disguise website has some more examples: https://www.disguise.one/en/

This seems to be good for the smaller shows and the best for interview type setting. I'm curious how it handles 2-3 hosts.

That 'ghost screen' that the BBC people were showing seems like a dimmed out screen which they have to interact with.

This has to make interviews more artificial feeling and requires experience to get used to talking into walls without fully seeing the other's expressions.

I could see the screen approach delivering a better production. But as others have mentioned it seems less flexible for a large scale production.

One problem I see a lot with these LED walls is that in close-up, the details of each individual LEDs destroy the video quality especially in live streamings that have to use ABR (or similar).

But then the video can't change perspective based on the camera position for the correct parallax views, or if it does the presenters get screwed on perspective.

Check out the Tom Scott videos - the presenters get a screwed up perspective, but sight lines work correctly.

Also, anything aligned with the video panels (most notably the floor) is correct from all angles.

Video walls can change perspective. They're heavily in use for shows like the Mandalorian among others.

They'd essentially just show what's being composited in behind them, and react to the camera tracking.

This is how the Mandalorian works

This is the Way

Take a look at how they filled the Mandalorian. Quite a lot of it was filmed inside a large video wall / cube. One of the big advantages for them was that it resulted in far more realistic lighting.

https://www.youtube.com/watch?v=gUnxzVOs3rk

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