Bounding Volumes

Bounding volumes are one way to decrease the amount of time spent on intersection calculations.

Enclose an object or objects that are expensive to intersect in a bounding volume whose intersection test is less expensive.

Example: If a ray doesn't intersect the sphere, it can not intersect the polygonal object inside.

If a bounding volume fits an object loosely, many rays that hit the bounding volume will miss the object.

Intersecting rays with simpler bounding volumes requires less calculations.

There is a tightness verses speed tradeoff!