Tuesday, 8 February 2022

How to Simulate Weight in Animation

Weight lift from the Animator's Survival Kit
One of the hardest things to achieve in 3D animation is the creation a sense of weight. Weight is hard to simulate because our characters are just pixels - they have no intrinsic weight, so we have to create it from nothing. 

One of the more tricky exercises our students at BNU have to tackle is to animate a character lifting a heavy object, such as a box. The box is just a bunch of pixels - it has no weight. So the challenge is to make it appear heavy.

To get started, take a look at the thumbnail sketches on the left, taken from the book we recommend all our students buy - The Animator's Survival Kit. 

The thumbnails show how important it is for the character to get their feet right underneath the object they are going to lift. That way, the weight of the object falls directly over the character's heels - and the object feels heavy. 

Get Those Feet Directly Under the Object
Both feet under the ball
Note how the character shuffles their feet forward to get them right under the ball. See the thumbnail sketch on the right, where the ball feels genuinely heavy, taking a close look at the feet. 

Then, the animator adds a vibration to the body as they start to lift upwards, making it feel really heavy and difficult. Maybe as the lift begins, the character keeps shuffling their feet forwards, to get them right under the centre of gravity. The harder the lift appears, the more heavy the object will feel.  

The Problem of Weight
To simulate weight, animators must learn to understand how gravity works.  This means understanding how our bodies move, how the physics works, and knowing where the weight is at any given point during any given action. 

Tell a Story
It's also important to tell a story. What is the character lifting, and why? What do they want? If you can create a sense of fun and entertainment around the shot, it becomes more than just a technical exercise. 

The Problem of Weight - Theory Video
To get started with the basic principles of animating weight, watch the video below:

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