Well, in the old days, you just put the splats in your 3d space, they weren't really sprites (in the strict sense that they didn't use dedicated sprite hardware). They're really interesting thing is that they're being used here to render the learned representation, but there's nothing particularly special about them or new or AI/ML about them.

You could "model" 3d objects with the gaussians by just putting a bunch together. It was a way to produce fast rendering 3d images without using a bunch of polygons. The results back then were...left behind by other techniques.

There's a massive back catalog of computer graphics work on the technique, it's usually just easiest to use the search tools and search back for all dates leading up to say...2021 and you'll find tons of normal old stuff like CS 302 - Computer Graphics courseware slides or whatever on the technique.

https://www.google.com/search?q=gaussian+splat+-site%3Apinte...