I typically only rely on the logical parent/child relationship between cells, and containment there is strict even if geometric containment is only approximate. The logical relationship is useful, for example, in providing a compact representation when you have a large collection of cells: https://h3geo.org/docs/highlights/indexing
I'll use the approximate geometric containment mostly just to get a rough idea of where cells are. For example, in the plots of cells covering California in the link above, plotting the "compacted" cells is still visually useful, even if you aren't seeing the exact boundaries of the uncompacted set it represents.
How do you typically leverage exact geometric containment with S2 in your applications? I'm curious because I work on H3 and h3-py (https://uber.github.io/h3-py), and maybe there's something we can build (or it already exists) that would fit your use case.
One example I am trying to wrap my head around is if you have two adjacent polygons (say California and Oregon) and perform an interior cover of both with variable hex sizes.
It seems possible that a child hex might actually slip outside the boundary - since the 7 children don't fit squarely inside the parent (no pun intended).
In S2 it guaranteed that any child cell of the S2CellUnion representing that cover is strictly inside the polygon bounds.
This doesn't seem to be guaranteed in H3. I could have a location that is in Oregon, that depending on the child resolution could slip into to Oregon instead of California - or vice versa?
Now imagine an business application where a user must be mapped to one of 2 physically exclusive regions, (for say pricing, legal, compliance reasons) it seems like exact containment is preferred.
Perhaps there is another way to employ H3 that would mitigate this?
I'll use the approximate geometric containment mostly just to get a rough idea of where cells are. For example, in the plots of cells covering California in the link above, plotting the "compacted" cells is still visually useful, even if you aren't seeing the exact boundaries of the uncompacted set it represents.
How do you typically leverage exact geometric containment with S2 in your applications? I'm curious because I work on H3 and h3-py (https://uber.github.io/h3-py), and maybe there's something we can build (or it already exists) that would fit your use case.