Efficient bounds in constructive solid geometry

Testing for intersection between geometric entities in ray casting is normally performed by intersecting a ray (a semi-infinite line) against the surface elements of a geometric model. Simple reasoning about the extent of each geometric entity significantly reduces the time required by such algorithms. If the ray and the geometric entities are boxed, one first tests to see whether the box around the ray and the box around a geometric entity overlap. Only if the boxes overlap does one continue to test to determine whether the ray and the entity overlap. A way to add boxes, called the S-bounds method, is described, and work to data on extending it is summarized. The method is useful for interference-detection and collision-detection problems.<>