3D Shape Matching with Quaternions (opens in new tab)

I believe this roughly the same algorithm used in matching protein structures using minimum RMSD, which used various methods over the years. https://boscoh.com/protein/rmsd-root-mean-square-deviation.h... https://en.wikipedia.org/wiki/Kabsch_algorithm and see also https://en.wikipedia.org/wiki/Orthogonal_Procrustes_problem