For the 3d artist, wishing to mimick real world shadows, shadow map shadows is the way to go. Shadow map shadows are used principally in phong based rendering systems. Even many ray tracers, uncluding formz allow the shadow map shadows to exist in an otherwise ray traced environment. The main adavatange of shadow maps over ray traced shadows is that they are faster, and can look more realistic , if used properly. That's the caviat.
Shadow maps are a lot harder to set up then ray traces shadows.
The distance of shadow casting light from the obscuring objects, and the distance from the fall of the shadow, like the floor. The higher the shadow map reslotion, the sharper the shadow. The higher the shadow map resolution the ram is required. The closer the distance beetween light and objects the sharper the shadow Try not to use more then 2 shadow casters per scene. Chapter 6.5.4 Casting Shadows on page 6 - 108.