This paper presents an algorithm for shadow calculation in dynamic polyhedral scenes illuminated by point light sources. It is based on a modi cation of Shadow Volume Binary Space Partition trees, to allow these be constructed from the original scene polygons in arbitrary order and to support for fast reconstruction after a change in scene geometry. Timings using sample scenes are presented that indicate substantial savings both in terms of computation time and shadows produced. KEY WORDS: shadows, BSP Trees, SVBSP Trees, dynamic modi cation.