Figure 4.17 shows the basic process of ray traversal through the tree. Intersecting the ray with the tree’s overall bounds gives initial tMin and tMax values, marked with points in the figure. As with the BVHAccel in this chapter, if the ray misses the overall primitive bounds, this method can immediately return false. Otherwise, it starts to descend into the tree, starting at the root. At each interior node, it determines which of the two children the ray enters first and processes both children in order. Traversal ends either when the ray exits the tree or when the closest intersection is found.