ABSTRACT
This chapter aims to understand how bounding boxes can decrease rendering times; and shows how to ray trace a number of object types including triangles and part objects. It explores the important role that compound objects play in modeling and discusses grids and triangle meshes—special types of compound objects that can contain millions of other objects. The most common bounding objects have the shape of rectangular boxes whose axes are parallel to world coordinate axes. Axis-aligned bounding boxes are also essential for placing geometric objects in acceleration schemes. Consequently, all objects that are included in acceleration schemes must have an access function that returns their bounding box. Most objects in computer graphics are represented by triangle meshes— collections of triangles with shared vertices. Rays can hit object surfaces on the outside, which is the same side as the normal points, or on the inside, and the shading must always be correct.
