Assignment #1: Bouncing Ball Basics

Assigned: Thursday, September 27th, 2012
Due: Thursday, October 4th @ 3:00 PM

Resources:

Part 1: Light vs. Heavy Bouncing Ball

On one sheet of paper, sketch out the poses of two different balls bouncing with forward momentum: a light ping pong ball and a heavy bowling ball. The two different motions should not overlap, but be easily comparable side-by-side or above-and-below. Draw enough frames such that we can see the balls roll to a stop. (You don't have to indicate the actual rotation in your drawings, but pay attention to the spacing.)

Assuming 24 frames per second, draw a pose every two frames. Make sure to emphasize the contrast between the different weights. Pay close attention to these principles:

  1. Timing. How does the rhythm of the ping pong ball bounces differ from the rhythm of the bowling ball bounces? Observe how these objects behave in reality. There are several ping pong balls available in the lab. Bowling balls are slightly harder to come by (if not a bit rough on the flooring), so check out video reference on the web. Here's one example.

  2. Spacing. When does the ball speed up? When does it slow down? This will also affect when squashing and stretching happens. Overlap drawings to signify deceleration and space them out for acceleration.

  3. Arcs. These should be included in every aspect of motion, as they serve to make animation more fluid and natural. Luckily, bouncing balls have built-in arcs. It may be helpful to sketch in the path of motion for each ball before drawing the poses.

  4. Squash and stretch. Keep in mind that you are animating a "normal" bouncing ball that doesn't have a mind of its own. Squash and stretch that is too extreme and that spans too many frames will make it look like the ball is willing itself to jump, and that's not what we want to see. A note for the future: you generally shouldn't see squash and stretch when your animation plays at full speed, but you should be able to feel it.

Part 2: 2D Animation

Take either your light ball or heavy ball from Part 1 and animate it in 2D using Photoshop. Use this template as a starting point. Take a look at the Photoshop 2D ball animation tutorial to learn how to accomplish this. You only need to animate it bouncing a minimum of three times. Turn in both the Photoshop file and a Quicktime render of your animation.

Extra Credit: Animate the other ball in 2D using the same technique.

Part 3: Bouncing Ball Obstacle Course Planning

Next week you will be animating a single bouncing ball with forward momentum from a side view in Maya. The catch is that the ball will be traversing a simple obstacle course. It will bounce until eventually rolling to a halt. This week you will prepare for the animation by drawing a series of poses, in essence constructing what is called a "planning sheet". Planning sheets are a concept we will go into more detail on as the quarter progresses.

An image with the correct proportions of the obstacle course and ball can be found here. Print out the image and draw your poses directly on the sheet. You will see that the set consists of an obstacle course with an upper and lower level. Your ball must start where indicated with its initial momentum directed by the arrow. It can be treated as if it is a ping pong ball, bowling ball, or anything inbetween. However, whatever physical properties you choose the ball must not be overly squishy nor can it be floaty like a partially deflated balloon. At a minimum the ball should fall into the lower level of the obstacle course and react appropriately to anything it touches. Draw the ball up to the point at which it comes to a rest.

Extra Credit: Add an obstacle and animate the ball contacting it (wall, ramp, bowling pin, etc). Any obstacle should be reactive! No extra characters or objects with momentum. And try not to go overboard with overly complicated models... the point is to focus on the motion itself!

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