There's a few innovative approaches to this, some of the done in real time. The "histopyramid" approach is used in the demoscene, and it's explained in the Fair

There's a few innovative approaches to this, some of the done in real time. The "histopyramid" approach is used in the demoscene, and it's explained in the Fairlight rendering secrets talk: https://www.youtube.com/watch?v=ZiPGd3DDfMU https://www.youtube.com/watch?v=ZiPGd3DDfMU It's maybe not suited to billions of points, but it's a decent start.