what is meant by linearization of BVH and bucket count for SAH?

Question

I am working on a CUDA ray tracer and doing some research work on it in which i am unable to find answer of few important questions:

1. What is the purpose of linearizing BVH during ray tracing? and
2. What is meant by bucket count for SAH (Surface area heuristics) binning ...
3. What is meant by binning through centroid of primitive?

Answer 1

Maybe it would have been better to split this into three SO questions, but anyway here's my try:

1. This could refer to at least two things, without more context I can't decide which:
   • To flatten out the tree structure of a BVH in memory into a simple array which can result in faster memory access / cache utilization.
   • It might also refer to the "Fast BVH Construction on GPUs" paper, which introduces the LBVH (linear BVH) structure.

2. Using buckets is a technique for speeding up SAH evaluation. Basically it helps to cut down the number of candidate splits. I can recommend Pharr & Humphreys' "Physically Based Rendering" book which explains and uses this.

3. Without more context, I don't know (and with more context as well, probably).