CAP 201a - Computer Animation I

Lesson 10 - Animation Basics

Objectives:

This lesson brings us to the main topic of the course. Objectives important to this lesson:

  1. The animation process
  2. Saving and modifying keyframes
  3. Animating different kinds of objects
  4. The Track View editor
  5. Animation principles
Concepts:

The lesson begins with a history lesson that probably should have been in the first chapter of the text. We have discussed some of these ideas already:

  • Early animation was based on devices that either displayed physical images rapidly or changed what a viewer was able to see rapidly. The text describes a thaumatrope. The link I have given you has instructions for making one.
  • Computer graphics did not exist until the invention of computers, but they provide many standard animation methods now
  • Computer animation can be two dimensional, but we will look at using 3DS Max to animate objects with three defined dimensions.

The lesson returns to a discussion of frames and keyframes, which were introduced in an earlier lesson. We are told that an animated movie, like any movie, is shown at a particular frame rate, which varies based on the standards that are used in different parts of the world. The NTSC (National Television System Committee) standard of 30 frames per second is the default frame rate for 3DS Max. The PAL (Phase Alternate Line) standard of 25 frames per second is mentioned as being a European standard. It is not the only one. Follow the link above for more discussion about NTSC, PAL, and SECAM.

The keyframe method of animation is a time saver. Keyframes are frames where we establish the position, rotation, and scale of an object. We do not have to establish these factors for every frame. If, for example, we set the values of these properties in frame 10, and set different values in frame 20, 3DS Max will fill in in-between frames at 11 through 19, creating the changes that must occur to get from the starting values to the ending values.

In an earlier lesson you were asked what color a keyframe is on the timeline. In this lesson you learn that what you saw before was only part of the answer. A keyframe is shown as one, two, or three colors, depending on what values change in it: red (position), green (rotation), and blue (scale). A keyframe can also be white, if it is a copy of another keyframe.

In this lesson, you use Auto Key to automatically create keyframes each time you make one or more changes in an object. You also use Set Key to create keyframes manually.

Exercise Notes and Questions

Work through the exercises and turn in your answers to all questions below as part of the homework for this assignment.

Exercise 1: This exercise illustrates using Auto Key to show a basketball going through a hoop and bouncing on the floor.
Question 1: Step 6 tells you to use the ALT-W key combination. What happens if you press it again?
Question 2: Step 7 tells you to choose Properties from the quad menu. This is almost correct. What is name of the option you should select?

The lesson continues with new material about Track View Curve Editor. Note that you will have to move it around the screen during the exercise to see what you will be working on. The Track View Editor lets you modify the action taking place at and between keyframes. To demonstrate several modifications you will make to motion in this lesson, the text tell you to play several .avi files in the folder for this lesson. It consistently refers to that folder as 11 - Animation Basics. The text is in error. The folder is 10 - Animation Basics.

Exercise 2: Exercise 2 simulates the experiment Galileo performed at the leaning tower of Pisa: he dropped two objects of different weights from the top of the tower to determine if they would fall at the same rate. (They did, and they do.) This exercise looks a little shaky at first, but if you follow directions, the two balls will look very realistic.
Question 3: This exercise assumes you learned to use the Track View tool in the previous exercise. What does the button look like that you click to change a tangent type to Fast?
Question 4: To check how high an object is in the scene, you are told in step 7 to watch the coordinate values at the bottom of the screen. How can you use the coordinate values to set the altitude of the object instead of moving it manually?

Exercise 3: This exercise sets up the next one, which demonstrates changing an object's position, rotation, and scale in the course of an animation. What puzzled me was the use of the phrase "gelatin cake". It may be easier to imagine the pre-made object as molded Jello, or a fruit jelly candy. Note: you will not be able to complete the exercise with the viewports configured as they are at the start. When you can't see what you are doing, stop and zoom out to get a better view of the scene.

Exercise 4: This exercise is based on the last one. It demonstrates changing an object's position, rotation, and scale in the course of an animation.
Question 5: In step 2, the text forgets to tell you to something. What is it?
Question 6: The exercise uses several terms for what might seem to be the same thing. Why is squashing the jelly in step 4 anticipation, while squashing it in step 13 is follow-through?

Exercise 5: This exercise animates a car on a race track. It is a long exercise, with many steps. Note that it is preset to have 600 frames in it. It illustrates the use of a Path Constraint, an animation device that controls an object by making it follow one or more splines. The text also describes three other animation controls:

  • LookAt Constraint - Controls an object by making it face or "look at" another object.
  • Noise Controller - Applies random motion to an object
  • Waveform Controller - Applies a slow application of an object's parameters, like gradually turning on/up a light

Question 7: What is the effect of adding two paths to the Path Constraint applied to the race car?
Question 8: Even though you apply the Path Constraint to the car, it does not keep its nose pointed in the direction of motion. What are the two settings you need to use to accomplish this for the car?
Question 9: What varies from frame to frame to move the car closer to the inside or outside border of the track?