Check out this new video by Brian Karis, where he explains all the nuances of how Nanite works.
Back in August, at SIGGRAPH 2021, an Engineering Fellow at Epic Games Brian Karis released a 155-pages-long document that explains literally everything there is to explain about Nanite, Unreal Engine 5's new virtual geometry system which enables the rendering of trillion triangle scenes at real-time framerates. How and why it was created, what it is able to do, what tasks can be accomplished with it, the tool's future, etc. Now, Brian has released a new video in which the information from the document is given in a more convenient way.
This lecture takes a deep dive into how Nanite works, from mesh import all the way to final rendered pixels. The team explains how the mesh-based data structure is built, streamed, decompressed, culled, rasterized, and finally shaded.