Topological space partition for fast ray tracing in architectural models

Fast ray-tracing requires an efficient acceleration structure. For architectural environment, the most famous is the cells-and-portals one. Many previous works attempt to automatically construct a good cells-and-portals. We propose a new acceleration structure which extends the classical cells-and-portals. It is automatically extracted from the topological model of a given building. It contains a low number of large volumes, all of them linked into a graph model. The scan of our structure is particularly simple and rapid, using all the topological information available from the topological model. The scan can be done for a single ray, or a wide ray packet. We show in this paper that our structure allows an interactive rendering even for large building models, with direct lighting from some thousands of point lights.