Squash and stretch is a fundamental technique used by animators to exaggerate movement and impressions of characters or objects. Though pioneered in the 1930s by Disney studios, it still remains an essential principle today.
When applied thoughtfully, squash and stretch can show weight, force, flexibility and emotion throughout the movement of any subject. This article will explore the technical concepts behind effective squash and stretch.
I- What is Squash And Stretch
By far the most important discovery was squash and stretch. Squash and stretch involve deforming an object or character along certain axes to exaggerate motion and impacts. Squash techniques reduce important dimensions, abruptly flattening objects against forces. Stretches elongate forms, exaggerating rebounds and elasticity. Together, these manipulate an object’s volume and proportions over time.
Though it was first introduced as one of the 12 Principles of animation as a 2D technique, the same rules and steps are applied to 3D animations as well.
When a fixed shape is moved about on the paper from one drawing to the next, the movement emphasizes a marked rigidity. In real life, this occurs only with the most rigid shapes, such as chairs, dishes and pans. Anything composed of living flesh, no matter how bony, will show considerable movement within its shape in progressing through and action.
A good example of this is the bent arm with swelling biceps straightened out so that only the long sinews are apparent. The figure crouched is obviously contracted into itself, in contrast to the figure in an extreme stretch or leap.
I highly recommend that you read Disney Animation: The Illusion of Life. A book by Frank Thomas and Ollie Johnston. It will highly impact your understanding of any topic related to animation.
II- Deep Dive Into Squash and Stretch
“Squash” means flattening or compressing along a certain axis, like a ball squashing vertically when bouncing. “Stretch” refers to elongating or enlarging a form, like a ball stretching vertically on the rebound. Used together, squash and stretch create the illusion of weight and flexibility. The same rule is applied when you add the z-axis to the equation.
The squashed position can depict the flattened out by great pressure or bunched up and pushed together. The stretched position always shows the same form in a very extended condition.
Squash compression occurs over just a few frames to communicate abrupt impacts. The “anticipation” build-up leading into the squash contributes to this effect. Stretches unfold more slowly to sell the elasticity and momentum. This timing contrast is key. Volume consistency must also be maintained. No matter how squashed or stretched, the total mass remains the same.
The best advice for keeping the distended drawings from looking bloated or bulbous and the stretched position from appearing stringy or withered was to consider that the shape or volume was like a half-filled flour sack. If dropped on the floor, it will squash out to its fullest shape, and if picked up by the corners, it will stretch out to its longest shape. Yet, it will never change volume.
III- Executing Squashes and Stretches
The technical execution of convincing squashes and stretches relies on a deep understanding of animation fundamentals.
Sharp timing is used over just a few frames for squashes to communicate impact. Volume is preserved by uniformly scaling along compressed axes. Mesh deformers and shape keys provide artistic control over the squashing effect. Proper edge topology flow must be maintained to avoid distortions during extreme flattening or compressions. Weight and force are emphasized through the extremity of the squash. Overlapped actions and secondary motion create follow-through.
Stretches unfold over more frames using slowed timing for anticipation. Volume is again preserved by uniform scaling along elongated axes. Bone scaling hierarchies and stretchy IK constraints are leveraged to achieve naturalistic stretching. It is crucial to order scale operations before joint rotations for natural motion. Rebounds and flexibility are exaggerated through extreme elongation. Overlapped actions like jiggling flesh enhance the effect.
Facial squashing and stretching require extensive shape key libraries for various mouth, eye, cheek poses and so on. Carefully painted blend weights localize deformations on the face. Corrective shapes maintain mesh quality at extremes. Character animation is driven by bones and control curves. Secondary jiggle dynamics on loose facial features add realism. Eyes, noses, lips, cheeks and other parts are squashed and stretched to enhance personality and acting.
The core guideline is to apply squash and stretch techniques in ways that serve the overall acting and storytelling of the character animation company. Convincing squashes and stretches make characters feel more dynamic, natural and appealing.
IV- Applying the Technique Thoughtfully
Squash and stretch should augment performances, not overwhelm them. Subtlety is key for believability. Overdoing these techniques results in cartoony distortion. Follow key principles like anticipation, slow-in and slow-out, overlap, follow-through and secondary motion. Allow the personality and mood of the character to dictate the degree of deformation. Make sure squashes and stretches contribute to storytelling rather than distracting.
Mastering squash and stretch allows animators to bring natural bounce, flexibility and expression to characters. These techniques remain vital tools for achieving the exaggerated magic of animation. When applied convincingly, squash and stretch can make the difference between a lifeless puppet and a charismatic, dynamic character. Understanding the foundational principles allows animators to utilize squash and stretch to maximum effect.
Conclusion
Though pioneered decades ago, squash and stretch remain one of animation’s most important techniques for bringing characters to life. Executed well, it imbues natural weight, flexibility and personality into every movement.
Squash and stretch require technical mastery of timing, volume preservation and deformation tools. Yet its true power comes from understanding the principles behind exaggerating motion realistically. Animators must apply squash and stretch with nuance and subtlety, supporting the acting and storytelling.
