Topic 2 - Bouncing Balls

For topic two, we were tasked to investigate the use of the animation principles and relationship between timing and weight by animating three balls of different weights bouncing in place and across the screen. The balls we had to animate were a soccer ball, a bowling ball and a ping pong ball. The focus of this topic was to show the relationship between the weight of the ball and the timing of the ball's bounces.

In the lecture we discussed the animation principles and how physics plays a large role in animation. The key animation principles are squash and stretch, anticipation, follow through, slow in and slow out, arcs, secondary action and timing. If an animation does not demonstrate realistic physics, a viewer will be pulled out of the experience and not believe into what they are seeing. While animating the bouncing balls in Maya, I realised that the principles timing and slow in and slow out were crucial in creating a realistic animation. 

Timing
Timing is what determines how many frames there are between an animation's key poses. In relation to animating a bouncing ball, timing determines how long it takes the ball to rise and fall. The aspect of timing can have an immense impact on the perceived weight of the ball. A ball that falls to the ground very quickly indicates it is very heavy, whereas a ball that takes a long time to fall and rise can indicate that ball is light.

Slow In and Slow Out
When a ball is bouncing, either in place or across the screen, it is battling with outside forces, the main being gravity. As a ball falls towards the ground it gains velocity and falls faster and faster until it is acted upon by the ground and bounces upwards. As the ball rises, gravity is pulling it back towards the ground. At the peak of a ball's bounce is where the balls upward acceleration and the acceleration due to gravity cancel each other out and causes the ball to start falling again. As the ball reaches it's peak, it is slowing down before reversing its direction. 

My Animations:

Bouncing In Place

Soccer Ball

When attempting to animate a soccer ball bouncing in place, I used a YouTube video as a reference to help guide my animation on how high the ball should bounce and how much upward momentum it should lose after every bounce. 

After analysing my reference video I attempted to animate a ball bouncing that reflected a soccer ball in Maya. After setting the heights of each bounce and manipulating the keyframes the animation did not look realistic as every time the ball was falling, it would slow down before hitting the ground. In physics, an object in motion tends to stay in motion unless acted upon by an outside force. The only force that should slow the ball down on it's decent is the ground, therefore, the ball should not slow down before it hits the ground, rather hit the ground and immediately change it's direction.

To correct this issue, I changed all the keyframes where the ball's y value was 0 (meaning the ball was on the ground) to be linear. This change meant the ball's fall did not slow down as it was approaching the ground. 

After making the keyframes where the ball's y value was 0 linear, I broke the tangents of these keyframes so I could manipulate their trajectory. By making these keyframes have a slightly steeper tangent the ball hangs in the air a little bit longer and as it falls it doesn't lose any velocity as a real ball wouldn't either.  

Bowling Ball

While animating a bowling ball bounce on the spot, I applied the same method of setting the heights of the bounces, making the keyframes when y is 0 linear and then breaking the tangents and making them slightly steeper as I used when animating the soccer ball. While I used the same method however, I had to make changes as a bowling ball has more weight and will lose a lot of upward momentum after every bounce. I again used a YouTube video as a reference. 

When animating the bowling ball bounce, I made sure to focus on how it's weight would impact how much upward momentum it lost after each bounce. The reference video showed that after the first bounce it loses a considerable amount of momentum, therefore resulting in the subsequent bounces to be smaller and smaller by a large factor. 

Ping Pong Ball

While following the same method for animating the soccer and bowling ball, I made sure to take into account how a ping pong ball bounces by utilising another YouTube video as a reference. 

Since a ping pong ball is so light, it loses very little upward momentum after every bounce. This causes the ball's bounces to lose little height and bounce for longer. 

Bouncing Across the Screen

Soccer Ball

To animate a soccer ball bouncing across the screen, I used the same YouTube video I used previously as a reference to gage how a soccer ball's forward momentum is affected by it's bouncing.

After my first attempt I realised the ball slowly gained forward momentum at the start of the animation and then slowly lost forward momentum at the end of the animation, this in turn causes the animation to look unrealistic. When a soccer ball bounces across a room, it slowly loses forward momentum over time.

To make the animation of the soccer ball bouncing across the screen more realistic, I changed the keyframe where the ball's x value is 0 (meaning it is at the starting point) linear. This meant the ball had a gradual decrease in forward momentum over time which produced a more realistic animation.

Bowling Ball

When animating the bowling ball bouncing across the screen, I made sure the ball lost forward momentum over time just like the soccer ball, however, due to the weight of the bowling ball it will lose forward momentum at a faster rate than a soccer ball would. By animating the bowling ball losing forward momentum at a quicker rate than a lighter soccer ball would, it makes the scene more realistic by showing the weight of the bowling ball both in it's bounces and it's forward movement.

Ping Pong Ball

When animating the ping pong ball bouncing across the screen I had to consider how little it weighed. While a bowling ball has a lot of weight and will lose upward and forward momentum very quickly, a ping pong ball is barley effected as it is so light. This is reflected in my animation as I made its loss of momentum over time much more gradual than the soccer and bowling ball. 

Reflection

While going through topic 2 and animating three balls of varying weights, both on the spot and across the screen, I learnt how physics and the animation principles can greatly dictate the realism of an animation and the relationship between timing and weight. 

By using real world physics in the animation, the balls look much more realistic. By making the ping pong ball lose less upward and forward momentum than the bowling ball emphasised the weight difference and illustrated the ping pong ball was much lighter. 

Focusing on the animation principles also showed the relationship between timing and weight. As timing determines how many frames are between an animation's key poses, in this case the balls when hitting the ground and the apex of their bounce, this can determine the perceived weight of the ball. A heavy bowling ball has a lot more weight than a ping pong ball, therefor the timing of their bounces will be different and reflect their respective weights.