Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 537

Displacement amount in seconds = maximum_displacement_time * (2 * (luminance_value – 128) / 256)
4 After Effects displaces each pixel in the image by replacing a pixel in the image at the current time with the pixel
in the same position at another time. The other time is the displacement amount in seconds for the pixel, calculated
in step 3.
Suppose you specified 2 seconds as the maximum time displacement. After Effects finds the luminance value of each
pixel in the displacement map, and then it replaces the corresponding pixels at the current time with pixels from
another time based on the maximum time of 2 seconds. A luminance value of 255 in the displacement map replaces
that pixel with the pixel 2 seconds ahead in the same position. A luminance value of 42 replaces that pixel with the
pixel 1.34 seconds behind in the same position.
Time Displacement Layer
Max Displacement Time (sec)
current time. Note that only luminance values of 0 or 255 (maximum darkness and maximum brightness) produce
the maximum time. All other luminance values produce times less than the maximum time.
Sets the number of frames per second in which to replace pixels. Typically, this value shouldn't
Time Resolution (fps)
be greater than the frame rate of the affected layer. Increasing Time Resolution can significantly increase rendering time.
Resizes the Time Displacement Layer to match the dimensions of the layer you're distorting. If
Stretch Map To Fit
this option isn't selected, the time displacement layer is centered in the composition.
Apply the Time Displacement effect
In the Composition panel, display both the layer you want to distort and the displacement map layer.
1
Hide the displacement map layer by clicking the Video switch in the Timeline panel.
2
3 In the Composition panel, select the layer you want to distort.
Choose Effect > Time > Time Displacement.
4
5 Choose a displacement map from the Time Displacement Layer menu, which lists all layers in the composition.
Grayscale maps are recommended.
Note: After Effects uses the layer you select in its original form, without any masking, effects, or transformations you
may have applied. If you want to use the layer with those alterations included in the displacement map, precompose that
layer using the Move All Attributes into the New Composition option. (See "Precompose layers" on page 118.)
Adjust the Time Displacement controls.
6
Timewarp effect
The Timewarp effect gives you precise control over a wide range of parameters when changing the playback speed
of a layer, including interpolation methods, motion blur, and source cropping to eliminate unwanted artifacts. The
Timewarp effect works independently of the Frame Blending switch in the Timeline panel.
Note: The Timewarp effect does not work on fields for interlaced footage. To use the Timewarp effect on a layer with an
interlaced footage item as its source, double the frame rate in the composition settings. When you render to final output,
modify your render settings in the Render Queue panel to set the frame rate appropriate for the output type.
This effect works with 8-bpc and 16-bpc color.
Specifies the layer to use as the displacement map.
Sets the maximum time, in seconds, from which pixels are replaced, before or after the
AFTER EFFECTS CS3 531
User Guide