How it works · Path B
A still scene has three dimensions. A performance adds a fourth one: time. That's where things get difficult.
Researchers have come up with three main ways to make splats move. Each one has its own tradeoffs.
Build a completely separate splat scene for every frame of video. It’s simple, but at 60 frames per second it takes up an enormous amount of storage. And because each frame is trained on its own, neighboring frames don’t quite line up, so the result shimmers.
Build one scene, then learn how to bend it over time. This is compact and works well for gentle motion. But anything that appears, disappears, or moves very fast is hard to describe as a bent version of something that was already there.
Make time a property of every splat. Each one knows when it exists and how it moves during that time. New things simply get new splats, and things that leave let theirs fade out. Mirage is built on this approach, because performers do exactly the kinds of things the other two struggle with.