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(a) (b) (c) (d) (e) (f)

Figure 1.8. Number of intersections per box (a–b, red) and per primitive (c–d, green).

The images show the differences between the SLBVH (a,c,e) and the BVH (b,d,f). The

last two images (e–f) combine the intersections of both boxes and primitives.

Intersections per box and per primitive. Besides the memory waste occasioned by

the heap’s scheme, the nonuniform primitives’ distribution is not handled opti-

mally by the partition algorithm. Many primitives end up sharing the same leaf

node, leading to an unbalanced tree. As a result, rays intersect few boxes but a

lot of primitives. As shown in Figure 1.8, the BVH do ...