How does paraview generate LODs?

Hello !
I would like to know how Paraview generates LOD (in Interactive Rendering Options). I went through the code, but it is a bit hard to understand really how it works. It seems to me Paraview uses vtkDIYkdtreeutilities to generate kdtree bounds and to proceed the LOD. Does someone know how Paraview LODs works (for pointclouds mainly) ?