[t8sr]

Octrees divide space into regular sized chunks. BVH divides space into chunks of varying size, but with a balanced population of bodies in each. The idealized BVH divides the population by 2 at each level.

Compared to octrees, BVHs deals well with data that’s unevenly distributed. At each level you split along the axis where you have the most extent. Finding the pivot is the interesting part. When I recently implemented a BVH from scratch, I ended up using Hoare partitioning and median-of-three and it worked really well. The resulting structure is well balanced, splitting the population of bodies roughly in half at each level, and that’s not even the state of the art, that’s just something my dumb ass coded in an afternoon.