5.5

218Motion User Guide
Shadows
Intro to 3D shadows in Motion
Motion projects that include point lights or spot lights can create more natural, realistic
effects by casting shadows. Shadows are created when an opaque or semi-opaque object
(a layer or group) blocks light from hitting another object. To see a shadow in Motion, you
need at least three things: A shadow-casting light source, an object to cast a shadow, and
another object upon which the shadow is cast. Multiple lights cast multiple shadows that
may or may not be visible depending on the relative positions and settings of the objects in
the scene.
Note: Ambient lights do not cast shadows.
In Motion, you can control whether a light source creates shadows and whether each
object in the scene receives shadows or casts shadows (or both). You can even have an
invisible object cast a shadow. The strength, sharpness, shape, and position of the shadow
depends on the type and positions of the lights and relative position of all three objects.
WARNING: Some changes you make to 3D objects cause shadows to disappear. This
occurs when the change causes rasterization of the 3D object—adjusting the opacity of
a group or turning on the glow attributes for a text layer, for example. Flattening the 3D
group allows it to cast shadows again. For more information about disappearing shadows,
see How rasterization affects shadows in Motion.
Cast shadows versus drop shadows
There are two common types of shadow effects used in motion graphics work: drop
shadows and cast shadows. Motion can create both effects, but because they have
different purposes and applications, it may be helpful to consider the differences
between them.
Cast and drop shadows simulate the effect of light blocked by an opaque object. But a cast
shadow is a 3D effect requiring a light source and an object for the shadow to fall upon,
whereas a drop shadow is a 2D effect simulating a cast shadow without a light source and
therefore is limited to a very small range of settings.