Adobe After Effects CS3 - Manual (Page 443)

AFTER EFFECTS CS3
User Guide
438
Vegas effect
The Vegas effect generates running lights and other path-based pulse animations around an object. You can outline
just about anything, surround it with a number of lights or longer pulses, and then animate it to create the appearance
of lights chasing around the object.
This effect works with 8-bpc color.
Stroke What to base the stroke on: Image Contours or Mask/Path.
Image Contours If Image Contours is chosen from the Stroke menu, you specify what layer to take the image
contours from and how to interpret the input layer.
• Input Layer The layer whose image contours are used. High-contrast, grayscale layers, and alpha channels work
well and are easy to work with.
• Invert Input Inverts the input layer prior to creating the stroke.
• If Layer Sizes Differ Determines how to adjust the layers if the size of the input layer differs from that of the layer
to which Vegas is applied. Center centers the input layer in the composition at its original size. Stretch To Fit scales
the input layer to match the layer to which Vegas is applied.
• Channel The color attribute of the input layer used to define the contours.
• Threshold The percentage value at which everything below or above is mapped to either white or black. This
property is important in determining the location of the edges that the effect strokes.
• Pre-Blur Smooths out the input layer before the threshold is sampled. Set this option to 0 if you have a high-
contrast image and want the stroke to follow the edges very closely.
• Tolerance Defines how tightly the stroke conforms to the input layer. A very high value results in sharp corners,
while very low values can make the stroking sensitive to noise.
• Render Specifies whether to apply the effect to a selected contour or to all contours in the layer.
• Selected Contour Specifies the contour to use when Selected Contour is selected from the Render menu.
Contours are numbered from left top to bottom right; the contour with the highest point is number 1, the second
highest point is number 2, and so on.
• Shorter Contours Have Specifies whether shorter contours have fewer segments. By default, the effect breaks each
contour into the same number of segments. For example, if you apply the effect to the letter R, the outside contour
may look fine with 32 segments, but the inside contour may be almost solid. To resolve this issue, select Fewer
Segments.
Mask/Path The mask or path to use for the stroke. You can use either closed or open masks.
Segments Specifies the number of segments used to create each stroked contour. For example, if the effect is applied
to the word Vegas and Segments is set to 10, the outline of each of the letters, plus the inner contours of e, g, and a,
are broken into 10 segments.
Length Determines the length of a segment’s stroke in relation to its maximum possible length. For example, if
Segments is set to 1, the maximum length of a stroke is one complete trip around the object outline. If Segments is
set to 3, the maximum length of a segment is 1/3 of the total outline, and so on.
Segment Distribution Determines the spacing of the segments. Bunched puts the segments together like boxcars in
a train: The shorter the segment length, the shorter the overall length of the train. Even spaces the segments evenly
around the contour.