Model madness revisited with BVH, Bounce Count: 16, 512 samples per pixel (Time to RayCast: 4 hours, 27 minutes and 33 secs)
The scene makes use of the Stanford Dragon (1,132,830 tris), Happy Buddha (1,087,716 tris), Armadillo (345,944 tris) and Bunny (69,451 tris) from the Stanford 3D Scanning Repository and the ordered polymesh version of Killeroo (46,000 tris).
Steam Bike with BVH, Bounce Count: 16, 512 samples per pixel (Time to RayCast: 1 hour, 11 minutes and 25secs)
Cornell Box Scene with BVH, Bounce Count: 16, 512 samples per pixel (Time to RayCast: 3 minutes and 25secs)
Stanford Bunny with BVH, Bounce Count: 16, 512 samples per pixel (Time to RayCast: 1 hour, 56 minutes and 8secs)
Image illustrating Bounding Volume Hierarchy
