In visibility real-time calculation phase, we firstly determine the view cell which the viewer is located in, and then use the potentially visible set of it to compute the visibility of the viewpoint, which can realize rapid 3D scene walkthrough rendering. 在可见性实时计算阶段中,首先获得视点所在的观察单元,然后使用该观察单元的PVS直接计算该视点的可见边,以此实现三维室内场景的实时漫游。