Indiana University
People  |    

Jim Krause | Classes | P354 Program Graphics & Animation

Week 11


  • Start thinking about your Final Project (60 seconds)
  • Just because you must include an element or technique in a homework assignment doesn't mean it has to be the primary thing. (Cookie for example.)
  • Remember to put CRAP to work in your movies.
    • Use Contrast to focus on your message.
    • Repeat visual elements, textures and movements.
    • Align your elements for a stronger comp
    • Place elements that go together in close Proximity to each other


  • Tuesday: Review homework & learn about Expressions
  • Thursday: Motion Stabilization

Parenting Review & In-Class Expressions Exercise - (Meyer chapter 17)

Parenting is a nice way to animate many objects at once. There are two ways to parent:

  • Reveal/display the "Parent" column in the timeline window. Then select the parent layer using the drop-down menu
  • Use the pick whip tool to select the parent layer

Parenting lets you assign the transform properties of one layer to another. A layer can only have one parent, but a parent can have multiple children. As demonstrated in the 3D lecture, Null Objects can be quite effective parents.

If you work through the Chapter 17 AE Project: [Ex.02*starter] , you'll get a fine grasp of parenting.

Revisiting Expressions

There's an interesting article/tutorial on Expressions on Creative Cow by Dan Ebberts. Check out this link for more info.

While Parent layers Transform Properties will be carried out in the Child Layer, Expressions allow for more complicated ways to connect different layers together. Instead of passing down all of the Transform Properties as in Parenting, Expressions let you connect a specific attribute to another layer's specific attribute- and the interesting thing is that the parameters don't have to match. For instance you can tie one layer's scale value into another layer's opacity.

Expressions are based on the JavaScript language and allow you to link layers together without keyframes.

You can create expressions with the pick whip tool or type in commands manually.

Remember that you can get to a property’s expression control tool by pressing Shit/Option/=

You should see 4 icons followed by an Expression field:

  • On/Off switch
  • Graph overlay icon
  • Pick whip tool
  • Expression language menu

To view only properties with expressions, select one or more layers, and then press EE on the keyboard.

To show the expression field in the Graph Editor, choose Show Expression Editor from the Choose Graph Type And Options menu at the bottom of the Graph Editor.

There is an entire forum on the Creative Cow website dedicated to AE Expressions:

You can go there to learn more about Expressions. The AE manual also has some useful examples.

The simplest way to use Expressions is to use the pick whip tool to link one layer’s parameter to the same parameter of another layer.

When the parameters match it's easy (scale linked to scale), but when the parameters don't match (some will need to be done). AE's built in help is uesful. Don't forget about the Expressions Forum on Creative Cow.

You can modify the script with simple mathematical functions found on the numeric keypad:

  • + add
  • - subtract
  • * multply
  • / divide
  • To reverse a parameter, add *-1 at the end of the script

Convert Audio to Keyframes - You can get interesting effects by connecting the amplitude (loudness) of an audio track to a parameter of another layer (E.g. scale). If you don't have any audio, you can find some in this folder from Week 6. To use:

  • first make sure your work area is set to the entire length of the comp- or to the duration of the layer you're going to create.
  • Select your audio layer
  • Under the "Animation" menu, select "KeyframeAssistant -> Convert Audio to Keyframes"
  • It will now make a null layer that you can connect an expression to.

Expressions In-Class Exercise (5 points)

  • Start with a 1280 x 720 composition. You can call it "timepiece".
  • Download the clock parts, which are in the "Week11" zip file. Move them into your media file and import the folder into AE, and into your composition
  • Note the clock face, and the hour and minute hand.
  • Start by examing the anchor points of the clock hands. They need to be positioned properly before animating. Once you've positioned the anchor points, move and scale the hands to their appropriate positions.
  • The goal is to connect the rotation of the hands so they accurately reflect the passing of time using Expressions.
  • To turn on the expression controls either press Shift Option = or Alt/Option click the Stopwatch
  • Look in the "Animation/Presets/Backgrounds" to find an interesting background for your clock.
  • Once you have successfully connected the rotation of the hands, see if you can apply an effect to the entire "family."
  • Make a nice background to use as a backdrop to your timepiece
  • Can you composite the timepiece so that it can be animated/moved as a whole?
  • Make the elements 3D and create a dynamic 3D move.
  • Once you are happy with your elements, make a movie and place it in your Week 11 folder. Make sure it's called timepiece. (Save it as a square pixel, MPEG4 or H.264)


Read Chapter 29 of the Meyer book and the following info on Motion Stabilization.

If you don't have your media from the Meyer book, download the video files which are zipped in this file (203 MB).

NOTE: These source video files are 4:3 standard definition clips. You likely want to work with a D1 or DV 4:3 comp size (720x486 OR 720x480).

Motion Stabilization

Tracking and Motion Stabilization commands can be found under the Animation menu.

Both of these use AE's ability to analyze footage.

To use Motion Tracking or Stabilization, first you must have a layer with changing frames (motion) and that has a distinct feature to track.

Load the as a comp

  • Be sure to set a Work Area encompassing your footage to track (important)
  • Position your time indicator at the beginning of your Work Area
  • Select the layer then choose Animation -> Track Motion

Look at your footage for a disctinct feature that is visible the duartion of the entire clip. Move the tracking area to the distinct feature.

The tracking area

  • The track point is broken down into 2 rectangles and an attach point.
  • The feature region is the smallest square. It should surround the distinct feature to be tracked.
  • The larger box is the search region. It is the area that AE will look for to find the distinct feature.
  • The point in the middle is the attach point. It represents the place of attachment for the track point.

To move the tracking area, drag in the area between the inner and outer squares. Adjust the feature region (inner square) to closely encompass the feature you want to track by dragging its handles. Adjust the search region (the outer square) only if you're tracking a fast-moving object.

You can track in a limited range of frames by first defining a work area.

  • Now press the analyze forward button (right arrow). It should track the area (if you've done things properly).
  • Now press the "apply" button. A prompt will ask "Apply Dimensions" - you want to X&Y.
  • Preview your footage.

Note how the edges of the video frame can become visible when footage is stabilized. Often one must scale up the video footage just a little to conceal this.

Warp Stabilizer - Now try the Warp Stabilizer command (also found under the Animation menu). Using the same footage try different methods and look at the differences (position / position, scale, rotation / perspective / subspace warp). Also note the different framing options.

Motion Tracking

Motion Tracking uses a technique similar to Motion Stabilization, but applies the tracking data to a different layer.

An interesting variation of Motion Tracking is Perspective Corner Pinning. This can be used to replace signs on billboards or other moving shots.

In-class Motion Stablization & Motion Tracking Exercise:

In this exercise you'll use at least two video clips to demonstrate that you can stabilize footage and carry out motion tracking.

  • Make a new comp 30 seconds long that matches your source video.
  • Using your own footage (or the provided peacock clips) stabliize at least one of them.

Hint: You might want to scale up the footage so that the moving edges aren't visible.

  • Add the AB_Recreation& (or another video clip with something you can motion track)
  • Make another layer (E.g. text: "Inspiration") that tracks along with the desired object

When you are finished, render out an H.264 movie called "video" and place it in your week 11 folder.

Perspective Corner Pinning (if time allows)

Motion Tracking uses a technique similar to Motion Stabilization, but applies the tracking data to a different layer.

An interesting variation of Motion Tracking is Perspective Corner Pinning. This can be used to replace signs on billboards or other moving shots.

Want to try it? Experiment on the file which was in the zipped folder from Tuesday.


Back to the P354 Home page