Abstract: Shadow testing of a two dimensional projection of a three dimensional scene is accelerated by superimposing the projection with a plurality of scan areas, then examining points, and edges of objects, falling within each scan area. Points are identified as potentially shadowed points if bracketed by edges of any object, and the bracketing object is identified as a potential shadower of the potentially shadowed points. Potential shadowers and potentially shadowed points undergo a series of tests to rapidly determine which, if any, of the potential shadowers are actual shadowers of each potentially shadowed point.