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Digital Video & Audio

Pixel Motion Blur effect, new in After Effects CC (12.0)

(For a complete list of what’s new and changed in After Effects CC (12.0), see this page.)

One of the new features in After Effects CC (12.0) isn’t really new at all. The new Pixel Motion Blur effect is a simpler way of using technology built into the Timewarp effect to “fake” motion blur.

The Pixel Motion Blur effect analyzes a movie to determine what parts are in motion, creates a set of motion vectors, and then uses that information to add motion blur within the image.

Chris and Trish Meyer have a great overview video on the Provideo Coalition website that shows what this effect can do.

The controls of the Pixel Motion Blur effect are a subset of those in the Timewarp effect:

  • Shutter Control: Choose Manual to set Shutter Angle and Shutter Samples for the effect independently. Choose Honor Layer Switch & Composition Settings to use the values set for the layer and composition.
  • Shutter Angle: Determines the intensity of motion blur. The shutter angle is measured in degrees, simulating the exposure caused by a rotating shutter. Simulated exposure time is determined by dividing the shutter angle by the frame rate times 360°. For example, a shutter angle of 90° causes an exposure of 1/96 of a second per frame: 90° / (360° * 24 fps).
  • Shutter Samples: Controls the quality of the motion blur. A higher value results in a smoother motion blur but longer rendering time.
  • Vector Detail: Determines how many motion vectors are used during interpolation. The more vectors used, the longer the rendering time. A value of 100 produces one vector per pixel. Note that increasing this value doesn’t necessarily produce better results in all cases; sometimes, a lower value may look better.

One common use for an effect like this that fakes motion blur is to add motion blur to a rendered result from a 3D program, rather than process the motion blur in the 3D program. The Pixel Motion Blur effect can add motion blur much faster than rendering the motion blur in the 3D program, but sometimes at the expense of quality, since motion blur that is created from the actual source of the motion is always the most accurate.

After Effects, Region of Interest