Lecture 9: Intro to Ray-Tracing & Accelerating Ray-Scene Intersection (90)
ld184
At which step does the surface area heuristic apply to the previous algorithm?
Gabe-Mitnick
The Surface Area Heuristic (SAH) is a tool to compare different options for where to put a partitioning plane. For the BVH partitioning algorithm on the previous slide, it's used in the line "For each of the B-1 possible partitioning planes evaluate SAH". For example, to evaluate the possibility of putting the partitioning plane between the first 2 buckets the remaining B-2 buckets, we estimate the cost of that partition with the SAH formula from slide 87:
surface area of (union of B1 and B2's bounding boxes) * (number of triangles in B1 + B2) + surface area of (union of the rest of the bucket's bounding boxes) * (number of triangles in the rest of the buckets)
We compute an estimate like that for each of the B-1 partition options and choose the one with the lowest estimated cost. (In the formula, I left out the C_trav + because it's the same for every option so it won't impact our choice of partition.)
At which step does the surface area heuristic apply to the previous algorithm?
The Surface Area Heuristic (SAH) is a tool to compare different options for where to put a partitioning plane. For the BVH partitioning algorithm on the previous slide, it's used in the line "For each of the B-1 possible partitioning planes evaluate SAH". For example, to evaluate the possibility of putting the partitioning plane between the first 2 buckets the remaining B-2 buckets, we estimate the cost of that partition with the SAH formula from slide 87:
surface area of (union of B1 and B2's bounding boxes) * (number of triangles in B1 + B2) + surface area of (union of the rest of the bucket's bounding boxes) * (number of triangles in the rest of the buckets)
We compute an estimate like that for each of the B-1 partition options and choose the one with the lowest estimated cost. (In the formula, I left out the
C_trav +because it's the same for every option so it won't impact our choice of partition.)