Hilbert Curve


The S2 curve is based on the Hilbert curve
The Hilbert curve is a function from the unit interval [0,1] to the unit square [0,1]×[0,1] that is *space-filling*, meaning that it visits every point in the unit square




> [S2 Cells](https://s2geometry.io/devguide/s2cell_hierarchy.html#s2cellid-numbering)







