Question

Describe 'Scale' in Dope Sheet.

Hint:

To change the speed of an action in the Dope Sheet, select your keys, activate Scale, and drag: pull outward to slow down the action, or push inward to speed it up.

Answer 1

Step 1: Understanding the Dope Sheet Interface:
The Dope Sheet (or exposure sheet) is an animation interface that displays keyframes as clean horizontal blocks on a spreadsheet-like grid. It is designed to make organizing timing and keyframe spacing easy.

Step 2: Defining the 'Scale' Operation:
In the Dope Sheet, Scaling is the process of stretching or compressing a selected group of keyframes relative to a chosen pivot frame. This operation changes the timing (speed/tempo) of the animation without changing the spatial coordinates or values of the keyframes.

Step 3: Mathematical Formulation of Keyframe Scaling:
If a group of keyframes is scaled from a pivot frame $F_{\text{pivot}}$ by a scaling factor $s$, the new frame number $F_{\text{new}}$ for any keyframe at $F_{\text{original}}$ is calculated using: $$F_{\text{new}} = \text{round}\left(F_{\text{pivot}} + s \cdot (F_{\text{original}} - F_{\text{pivot}})\right)$$ [noitemsep]
• If $s > 1.0$, the keyframes spread farther apart, slowing down the animation.
• If $s < 1.0$, the keyframes compress closer together, speeding up the animation.