[boulos]

As aek and dahart said, updating a BVH (refitting) is not expensive. If anything, it's bandwidth limited.

The challenge is minimizing the cost of (selectively) rebuilding.

[GfxGem]

The method from the paper safes both, memory bandwidth and compute time. You animate and write (to memory) a way smaller number of vertices. You update a smaller (less memory bandwidth, less compute) BVH.

[forrestthewoods]

That’s just another way of saying “updating a BVH is expensive therefore spend effort to minimize the amount of updating it”.

The fastest code is the code that never runs.

[dahart]

There’s a material algorithmic difference between rebuild and refit. Not sure if that point was clearly understood.