Here is the somewhat neglected original 2009 dissertation by Federico Ponchio, the guy who invented the dynamic mesh simplification algorithm on which Nanite is

Here is the somewhat neglected original 2009 dissertation by Federico Ponchio, the guy who invented the dynamic mesh simplification algorithm on which Nanite is based, with lots of illustrations: https://vcg.isti.cnr.it/~ponchio/download/ponchio_phd.pdf https://vcg.isti.cnr.it/~ponchio/download/ponchio_phd.pdf (107 pages!)