Shadows Shadows in a rendered scene give objects the illusion of weight and keep them from appearing to float. Raytrace shadows are calculated by casting sample rays from the light source to the objects in the scene and determining what objects light between the light and other objects. Raytrace shadows tend to be crisp and are best used for exterior scenes in bright sun or scenes requiring harsh lighting effects. Shadow Map . With shadow maps, each light generates depth information for the objects in its scope, and a grayscale bitmap is composited into the scene at render time to simulate shadows.
Mapped shadows are generally preferred.
Raytrace shadows are more mathematically intensive and can take longer to generate, but use less computer RAM than Shadow Map shadows. When using Raytrace shadows, always try setting the Max Quadtree Depth setting in the Ray Traced Shadow Params. Rollout to 10 to increase raytrace speed. Shadow Map shadows create grayscale bitmaps that must be stored in RAM for compositing at render time to create the shadows in a scene. Many shadow casting lights can use all the available RAM and cause the computer to page to disk during rendering, thereby reducing render speed to unproductive levels.