You're looking at something called a "neural radiance field" backed by a sparse, low resolution voxel grid and a dense high resolution triplane grid. That's a bit of a word soup, but you can think of it like a glowing fog rendered with ray marching.
The benchmark details are a bit complicated. Check out the technical paper's experiment section for the nitty gritty details.
The benchmark details are a bit complicated. Check out the technical paper's experiment section for the nitty gritty details.