They mention they cannot push enough GPU juice to the screens, so they only render the camera focus area in full resolution. Also there is 12 frame lag which prevents moving camera too fast.
One solution to this would be to put the camera on a fixture that replays the same motions every time, so they can do a 'dry run' and correct the rendering. (Putting a camera on a fixture is not new, IIRC they did it in Back to the Future - https://www.youtube.com/watch?v=AtPA6nIBs5g is a really good yet succinct documentary on it)
They did. They only had so many models of the spaceships, so multiple takes with a programmed camera path and compositing was used to increase the number of vessels in the scene.
I don’t fully get this. They could just employ different computers to render different parts of their cave. It seems more like a cost savings thing than a technical limitation.
And I’m not sure why you’d skimp on a few PC’s if you’re already building a humongous led wall, so maybe there’s something I’m missing.
I worked in a somewhat similar project in 2015, though not as complex as this, to build background videos for DotParty, using UE4 for panoramas and then stitching them. One of the hugest issues we found was that, because of this being a game engine, a lot of things are not deterministic, so if we used multiple cards or computers, particles and other environmental effects would not be in sync, and the stitches were glaring.
I believe it's been improved in later versions, as they've focused in these use cases, and there might even be deterministic particles now, but I'm not sure, because I've been out of the VFX market for quite a while.
The part you are missing is the insane complexity involved in keeping perfect frame sync with a low latency across GPUs and machines, especialliy when some final compositing of partial outputs is involved. The stuff sounds simple on paper and it looks like you can just go buy the tech, unpack it and switch it on. The reality is nothing like that. The off the shelf tech is fiddly and barely stable because it is always a low priority feature added with the least possible effort.
The overall latency says nothing about the sync precision required. The displays need to be synced and the graphics cards need to have their vsync synchronized between them (usually via dedicated hardware). If the displays are out of sync, you immediately get visible tearing at the seams.
If your parallel renderer divides the image along a grid that does not correspond to display boundaries, you need to gather and composite the partial framebuffers after rendering them. This means that you're now sending frames across the network amd you need to take care that you aren't compositing frames from different timesteps, for example, because the the part of the rendered framebuffer that goes to compositor/display node A arrived in time, but the part going to compositor/display node B somehow didn't.