6.5. Intersection Tree Generation.   

Intersection Tree
Fig. 6.3 : Intersection Tree
Figure 6.3 has been taken from [WHIT 80] and demonstrates the generation of the tree. Each initial ray projected into the scene will produce an intersection tree if it strikes any object within the viewing area. A node is added to the tree each time an object is intersected. This node now forks off two possible new rays, one for the reflected ray (if the object reflects light) and one for the transmitted ray (if the object is transparent). Each of these two new rays is then tested to see if it intersects any objects within the viewing area, and so on. Theoretically, this process could go on ad infinitum. Therefore, most ray tracing algorithms allow the user to specify the maximum level to which the tree will be generated.