CAP 151 -
Introduction to Computer Animation
Lesson 8 - 3D Space
This lesson demonstrates After Effects approximation of 3D. Objectives important to
- 3D layers
- Moving layers in 3D
- Rotation in 3D
- Camera track and orbit tools
- 3D lights
Although After Effects is a 2-dimensional program, it has some 3D features that are worth using. The text refers to turning on the 3D features for a layer as placing the layer into 3D space.
Tutorial Notes and Questions
Work through the exercises and turn in your answers to all questions below as part of the homework for this assignment.
Tutorial 1 (Basic 3D):
- Open the project and comp file indicated on page 192. Review the bullets in this step about how 2D layers work, to contrast that with what you will see about layers in 3D space.
Check to see that the Switches column is visible. Turn on the 3D Layer switch for both text layers in the comp, and display the Position values as instructed.
Scrub the z-axis Position value for the Dimension layer to move it toward the viewer and away from the viewer. The text refers to this idea as how far away a layer is from the camera. In every scene you have made so far, there has been one default camera.
This step shows us that the mouse pointer (cursor) can appear as it has in the past, or it can include an axis letter, as shown on page 194, when movement is constrained to one axis. To see an axis letter on the mouse pointer, hold it near an axis arrow of a layer. This is also a good place to point out that the axes are color coded: red for the x-axis, green for the y-axis, and blue for the z-axis. The mnemonic is RGB=XYZ.
Reveal the Rotation parameter for the Dimension text layer, and note the new sub-parameters that appear for a 3D layer.
- 2D layers use stack order to determine what layers show in front (on top) of other layers; 3D layers use their z-axis position to determine this
- 2D layers can move on the x (left and right) and y (up and down) axes; 3D layers will move on the z (forward and backward) axis as well.
- 2D layers rotate on their anchor points; 3D layers can rotate on any of the three axes (more on this in a few steps)
Step 6 reveals that 3D layers do not have any thickness. To prove this, rotate one until you see the edge of it. Complete the tutorial as instructed in the text.
- Z rotation is the kind of rotation we have been using (rotating on the anchor point)
- Y rotation rotates the layer on its y-axis. Imagine a revolving door: it spins on a vertical pin driven through its y-axis.
- X rotation rotates the layer on its x-axis. Imagine a paddle wheel on steam boat that's steaming away from you. The link here is to a video of a stern-wheeler. (Excuse me, I'm going to think about Mark Twain for a few minutes...) It is fair to note that as the steamboat video begins, the camera is beside the wheel. From this perspective, you could say that the wheel is spinning on its z-axis. When the camera is behind the boat, you could say it is rotating on its x-axis. This concept depends on thinking of the axes as they are seen by the viewer.
Tutorial 2 (Multiplaning) This exercise introduces a concept that you may not have thought about. What do you see when you ride in a car and look out a side window? Scenery goes by sideways. However, it does not all go by at the same rate. Objects that are close to you go by quickly, but objects that are far away seem to go by more slowly. Consider the view through the car window in this video. Objects at the side of the road are in the frame only for a moment, while objects near the horizon are in the frame much longer. In this exercise, you set up multiple planes (layers) that move by more quickly the closer they are to the viewer.
- Open the project and comp file indicated on page 196. The ten layers in this comp will move across the frame from right to left.
- Select all layers and enable 3D for them, as instructed. Reveal the Position transform for all of them as well.
Question 1: What do you press to deselect all layers after you follow the instructions above?
- The authors forgot to put in a step 3. (Second edition of the book, and it's still missing.)
- A new trick: follow the instructions to open two views of the comp at once.
- Set the panels to Active Camera and Top view as instructed.
- Change the z-axis position of the various objects in the scene, but leave the null object alone.
- Run a preview of the comp, and note that After Effects will figure out that the farther an object is from the viewer, the slower it should move. Tweak as necessary to make it more realistic, save it, and run it for me in class.
Tutorial 3 (3D Animation): In this exercise you are shown that you can have several views of your comp/scene open at the same time, enabling you to correct animation on all axes at the same time.
- Open the comp specified.
- Set Position keyframes for the two text layers at timeline marker 1:00.
Question 2: This should be review. What is the keyboard shortcut for turning on the Position stopwatch?
- Move the text layers 2-dimensionally as instructed. Follow the instructions to drag each text layer on its z-axis. Note that the instructions to drag left and right may be reversed for one or both layers.
- Change the view in the comp window as instructed, eventually splitting it into four panels, each having a different view of the scene.
- Use the Bezier handles as instructed to change the path of each text layer. Note that making a change in one view will make changes in all the others. Sometimes a change will create the need for another change to get the desired effect in all dimensions.