Customized Object Hierarchies

Object hierarchies are useful for different rendering applications. In hierarchical radiosity, for instance, the quality of lighting simulations can be improved through well-adapted object hierarchies. Using a different criterion for constructing the hierarchies may lead to significant speed-ups for typical ray tracing applications. In this paper we introduce a new method for automatically creating object hierarchies. Our algorithm inserts all scene objects sequentially into the hierarchy created so far. The insertion decision is based on a user-defined cost function. Thus the algorithm can be guided to create customized object hierarchies appropriate to the desired application. In addition, a global optimization may be used to improve the completed hierarchy even further. During this optimization step ill-formed groups are eliminated by breaking up or splitting. The results obtained with our method demonstrate the benefit of customized hierarchies over traditional ones