TECH TIPS
Frame by Frame Sequencing
Advanced Techniques in Illustrator and After Effects, Part 2
by Ben Bardens
In this tutorial, I’ll show how to take a layered Adobe Illustrator file into After Effects and use the sequence layers command to expose the layers as an animation sequence; in this case, an animated star. In part one of this tutorial (Editors Guild Magazine, MAR-APR 07), we created an Adobe Illustrator file using the shape tools and blend tools to create a shape blend for animation. Each layer of the file contains a different frame of the animation, like a stack of drawings all contained within a single file. If you have this file you can use it to complete the tutorial below. Or you can download the file from: www.barkanimation.com/guild/23.zip.
These techniques for sequencing layers are particularly useful for creating traditionally animated effects in which you have a different drawing or graphic for each frame of your animation. Keep in mind these techniques are not specific to layered Illustrator files. The source file could also be a layered Photoshop file, or even a folder full of individual frames (aka an “image sequence”), such as a TGA sequence, SGI sequence, or just about any other image sequence format.
After you sequence out the layers to create the animated star, the last part of the tutorial walks you through how to nest the element, add additional effects and use it as a particle in the Foam filter.
Importing an Illustrator composition and sequencing layers in After Effects
Open After Effects and choose File -> Import -> File.
Locate the “star-sequence.ai” file. Before clicking “Open,” change the pop-up menu for “Import As” to “Composition.”
In the project panel, double click the “star sequence” composition to open it.
Choose Composition -> Composition Settings.
In the Composition Settings dialogue box, change the duration to 2:00. Click OK.
Choose Composition -> Background Color. Using either the eyedropper or the color swatch, change the background color to white. Click OK.
Click in the Timeline panel to make it active, then type Command-A (Mac) or Control-A (PC) to select all the layers.
These next two steps will determine the animation exposure for your sequence, or the length of time that each layer will be on camera in the resulting animation. Stepping forward one frame and setting the outpoint will result in an animation sequence in which each layer is on camera for two frames (or on “twos” as an animator would say). Stepping forward two frames will result in an animation sequence on “threes.” Stepping forward no frames will result in an animation on “ones.”
Use the Page Down key to step forward one frame.
Type Option ] (Mac) or Alt ] (PC) to trim the outpoint for all the layers to the current time indicator.
Push the Home key on your keyboard to return to time = 0.
Choose Edit -> Deselect All.
In the timeline, scroll down and click on Layer 31 to select it.
Scroll back to the top of the timeline and shift-click on Layer 2. All the layers should now be selected again.
Important point: The order in which you select your layers determines the order they are sequenced by the Sequence Layers command.
 Figure 1: Use the Sequence Layers command to automatically distribute layers along your timeline. |
Choose Animation -> Keyframe Assistant -> Sequence Layers (see figure 1).
Leave Overlap unchecked and click OK.
Push the Zero key on the numeric side of your keypad to load a RAM preview and view your animation.
At this point, you should save your project file and experiment further. To sequence the layers so the animation plays in the other direction, do this: Go to time = 0, select all, push the [ key on your keyboard, then repeat the last six steps, beginning with Choose Edit -> Deselect––except select Layer 2 first and Layer 31 last.
After exposing and sequencing your animated star, you can nest it and apply special effects or use it as an element in another animation of effect filter. The next series of steps stylize the animated star further, and use it as a particle in the Foam filter:
In the Project panel, drag the “star-sequence” composition to the new composition button at the bottom of the project panel.
In the new “star-sequence 2” composition that is created, select the “star-sequence” layer and push “R” to display the rotation property. Set two rotation keyframes, one at time = 0 with a value of 0, one at time = 1:29 with a value of 180, to spin the star 180 degrees.
To change the background color of the composition to black, choose Composition -> Background Color.
With the layer still selected, choose Effect -> Color Correction -> Tint.
In the Effect Controls panel that opens up, change the “Map Black To” color swatch to a new color, such as yellow.
Duplicate the layer by choosing Edit -> Duplicate, or by typing Command-D (Mac) or Control-D (PC) on the keyboard.
With the duplicate layer selected, choose Effect -> Blur & Sharpen -> Gaussian Blur. In the Effect Controls panel, change the Blurriness value to 3.
Also, in the Effect Controls panel for the duplicate layer, change the color swatch for the Tint filter “Map Black To” property back to white (or some other color).
 Figure 2: The layer Transfer Modes button in the bottom left corner of the timeline panel. |
Back in the Timeline panel, display the Transfer Modes column by clicking the Transfer Modes button in the lower left corner of the Timeline (see figure 2).
With the duplicate layer still selected, choose Classic Color Dodge from the Transfer modes pop-up menu (see figure 2).
Choose Composition -> New Composition. In the Composition Settings dialogue box, name the composition “Foam Effect.” Choose the “NTSC D1 Square Pixel” setting from the presets pop-up menu, and change the duration to 10 seconds, then click OK.
From the Project panel, drag the “Star Sequence 2” composition into the new “Foam Effect” timeline.
Turn the video switch off for the “Star Sequence 2” layer in the timeline.
Choose Layer -> New -> Solid. In the Solid Settings dialogue change the name to “Foam effect,” click the “Make Comp Size” button and specify the color as black, then click OK.
With the “Foam Effect” solid layer selected in the timeline, choose Effect -> Simulation -> Foam.
In the Effect Controls panel, change the View from “Draft” to “Rendered,” then click the arrow next to “Rendering” to expand its properties.
 Figure 3: Specify a custom "Bubble" for the Foam filter by first changing the Bubble Texture and then specifying which layer to use. |
To specify our animated star as the particle for the effect, first change the “Bubble Texture” to “User Defined.” Then change the “Bubble Texture Layer” to Layer 2, the “Star Sequence 2” layer (see figure 3).
Preview the results. Looks good, except there’s one obvious problem: Because the animated star only lasts two seconds, the particles all disappear prematurely for our Foam effect. To solve this, we can add Time Remap and a simple expression to our Star Sequence 2 layer.
Select the “Star Sequence 2” layer and choose Layer -> Time -> Enable Time Remapping.
In the timeline, extend the outpoint handle for the “Star Sequence 2” layer so that it extends the full duration of the composition (see figure 4).
Option-click (Mac) or Alt-click (PC) on the stopwatch icon to the left of the Time Remap property for “Star Sequence 2 layer.” In the expression entry field that appears to the right, enter the following expression: loopOut (type = “pingpong”).
 Figure 4: Click directly on the layer outpoint handle and drag to the new duration. |
Preview the results. The particles now stay on screen for the duration, except there is an empty frame where the star loops back and forth. To correct this, simply change the value for the second Time Remap keyframe to trim out this frame. To do this, put the time indicator at two seconds, so it is sitting directly on the keyframe. Then simply click on the value to the right of the Time Remap property and change it from 2:00 to 1:29.
Experiment further by adjusting the properties under the “Physics,” “Producer” and “Bubbles” groups within the Foam filter. Try setting some keyframes for “Producer Point” to animate the origin of the particle stream.
Ben Bardens teaches After Effects at Glendale Community College and works as a freelance graphic artist. Learn more about his classes by visiting www.glendale.edu/~bbardens or by e-mailing him at bbardens@glendale.edu.
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