Turning shadows on and off
Most lights have shadows turned off by default. When they are turned on, renderable objects within the light's range cast shadows as well as receive them. We've already seen how to turn off shadows for individual objects by excluding them from a light. If you want, you can turn off shadow casting as well as shadow receiving using the Object Properties dialog box.
To turn on shadow casting:
Select a light that shines on some objects. Make sure there is a surface within the light's range for shadows to fall on.
Open the Modify panel.
In the General Parameters rollout, check Cast Shadows.
In the Shadow Parameters rollout, check On in the Object Shadows group (Figure 1).
Figure 1 Lights don't cast shadows by default, but you can turn on shadow casting on these rollouts.
Render the scene (Figure 2).
Figure 2 A scene rendered with shadows.
To turn off shadows for an object:
Select an illuminated object.
Right-click the object.
In the pop-up menu, choose Properties.
In the Object Properties dialog box, uncheck Cast Shadows and/or Receive Shadows (Figure 3).
Figure 3 The Object Properties dialog box lets you turn off shadow casting on a per-object basis.
Render the scene.
The object no longer casts and/or receives shadows (Figure 4).
Figure 4 The salt shakers still cast shadows, but the teapot doesn't.