I know that intersection tests can typically (for hit detection in games) be computed in log n time with reasonable accuracy, but there is a problem that I see with using hierarchical bounding volumes in ray tracing. For example, a ray may intersect a bounding volume however due to the shape of the contained object it may turn out that the object has not been intersected. For hit detection in games this typically doesn't matter and a hit can be assumed, but a ray needs to actually intersect a low level primitive to draw a pixel. When the test is performed in a bounding volume and it turns out no intersection took place the algorithm would have to back-track, and I'm not sure this complication would still retain log n properties. So how are intersection tests performed where such precision is required and is log n still achieved? I know I have to do my own homework on the implementation but I'm just interested in the vague idea and maybe the name of the algorithm, thanks.