Motion blur – Adobe After Effects CS4 User Manual
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USING AFTER EFFECTS CS4
Animation and keyframes
Last updated 12/21/2009
You can paste any of these paths into the Position or Anchor Point property for a layer, or into the position property
of an effect control point. The pasted keyframes are set to rove in time, except for the first and last ones, to create a
constant velocity along the path.
By default, the duration of the pasted motion path is 2 seconds. You can adjust the duration by dragging the first or
last keyframe in the Timeline panel.
1
Copy a path to the clipboard:
•
Select a Path property in the Timeline panel, and choose Edit > Copy.
•
Select a path in Illustrator or Photoshop, and choose Edit > Copy.
2
In the Timeline panel, select the property into which to paste the path.
3
Place the current-time indicator at the time for the first keyframe of the motion path.
4
Choose Edit > Paste.
More Help topics
Copy a path from Illustrator, Photoshop, or Fireworks
Motion blur
When you view one frame of motion-picture film or video containing a moving object, the image is often blurred,
because a frame represents a sample of time (in film, a frame is 1/24 of a second long). In that time, a moving object
occupies more than one position as it travels across the frame, so it doesn’t appear as a sharp, still object. The faster the
object moves, the more it is blurred. The camera shutter angle and shutter phase also affect the appearance of the blur,
determining how long the shutter stays open and when the shutter opens relative to the beginning of the frame.
In contrast, in a single frame of a computer-generated animation, you may not be able to tell which objects are moving
because all moving objects may appear as sharp and clear as nonmoving objects. Without motion blur, layer animation
produces a strobe-like effect of distinct steps instead of an appearance of continuous change. Adding motion blur to
layers that you animate in After Effects makes motion appear smoother and more natural.
You enable motion blur for each layer individually, and you also determine whether the motion blur is rendered for
previews and final output. Use the Enable Motion Blur composition switch
at the top of the Timeline panel to
enable or disable motion blur rendering for previews. Modify the render settings in the Render Queue panel to enable
or disable motion blur rendering for final output. If the Switches Affect Nested Comps preference in the General
preferences category is enabled, then nested compositions obey the setting for the compositions in which they’re
contained. (See “
About precomposing and nesting
Motion blur slows rendering, so you may want to disable the composition switch while working, and only enable it
when you need to see the finished result.
To enable motion blur for a layer, do one of the following:
•
Click the Motion Blur
layer switch for the layer in the Timeline panel.
•
Select the layer and choose Layer > Switches > Motion Blur.
The number of samples that After Effects uses to calculate motion blur adapts for each layer, depending on the motion
of that layer. This adaptivity provides high-quality motion blur without unnecessarily sampling the motion of a slow-
moving layer as frequently as the motion of a fast-moving layer. High sampling rates decrease rendering performance.