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The Vegas effect generates running lights and
other path-based pulse animations around an object. You can outline
just about anything, surround it with 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.
John
Dickinson provides an example on his Motionworks website of an EKG (electrocardiogram)
simulation created using the Vegas effect.
- 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 before creating the stroke.
- If Layer Sizes Differ
- Determines how to adjust the layers if the size of the input layer
differs from the size 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 high value results in sharp corners, while 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 upper-left to lower-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 the stroke of a segment 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.
- Rotation
- Animates the segments around the contour. For example, to
create the appearance of running lights, start with a large number
of segments set to 50% of their length, and then animate Rotation
to move the lights around the shapes.
- Random Phase
- Specifies that the stroke starting point is different for
each contour. By default, the effect strokes a contour beginning
at its highest point on the screen. In the event of a tie, it starts
at the leftmost highest point.
- Blend Mode
- Determines how the stroke is applied to the layer. Transparent creates
the effect on a transparent background. Over places the stroke over
the existing layer. Under places the stroke behind the existing
layer. Stencil uses the stroke as an alpha channel mask, filling
the stroke with the pixels of the original layer.
- Color
- Specifies the color of the stroke, unless Stencil is chosen
for Blending Mode.
- Width
- Specifies the width of the stroke in pixels. Fractional values
are supported.
- Hardness
- Determines how sharp or blurry the edges of the stroke are.
A value of 1 creates a slight blur; a value of 0.0 blurs the line
so that few solid areas of color remain.
- Start, End Opacity
- Specify the opacity at the beginning or end of the stroke.
- Mid-point Opacity
- Specifies the opacity of the midpoint of the stroke. This control
works in terms of relative opacity, not absolute opacity. Setting
it to 0 makes the change in opacity smooth from the start point
to the end point, as if there were no midpoint at all.
- Mid-point Position
- Specifies the location of the midpoint within a segment: Lower
values move the midpoint closer to the beginning; higher values
move the midpoint closer to the end. Use this control to move the
midpoint opacity from the center of the stroke.
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