Parallel Computer Architecture

3.5 The Parallel Application Case Studies: An In-Depth Look 175

primitives per leaf is defined by the user, as are some other aspects of the tree struc-

ture).

The hierarchical grid or tree makes it efficient to skip empty regions of space

when tracing a ray and quickly find the next interesting cell.

The Sequential Algorithm

For a given viewpoint, the sequential algorithm fires one ray into the scene through

every pixel in the image plane. These initial rays are called primary rays. At the first

object that a ray encounters (found by traversing the hierarchical uniform grid), it is

first reflected toward every light source to determine whethe ...