‍Animation is an exciting discipline and a fantastic tool for telling stories that would otherwise be difficult to explain or articulate with words. From particles to characters and renderers to AI; animation is as wide as it is deep and with that comes a lot of technical and creative lingo. At doodledo we always try and ‘speak human’ where possible, but sometimes the native language of the animator finds its way into conversation. 

So, for those situations, here’s a quick guide to understanding what animators might be going on about.
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Alpha Channels
Alpha is another word for transparency, opacity or how see through something is. But an alpha channel uses black (transparent), white (opaque) and grey values to create a transparency map which tells software which parts can be visible and by how much.

Ambient Occlusion (aka AO/AO pass)

This is something that makes 3D objects look more realistic by adding shadow detail based on shape rather than light - it is how a computer simulates “contact shadows” or dark areas where objects get close to each other as well as in corners and crevices. It’s a trick animators can use instead of computed shadows as it is faster for computers to process

Caustics (or caustic refractions)

If you’ve ever looked at the light dancing around a glass of water on a sunny day you may well be experiencing caustic refraction. This is where light refracts off the glass and/or water and creates hot spots. This is an effect used in 3D animation to sell translucent materials and liquids as real. 

Ease-in/Ease-out/Easy-ease

If you think these sound like dance moves then you might be closer than you’d think. These terms all refer to acceleration (changes in velocity). A fast movement will have big distances between frames and a slow movement will have small distances; easing is when we make an object accelerate or decelerate - therefore making distances get bigger with each frame (easing out) or smaller with each frame (easing in). An easy-ease is when something slows into a position then accelerates out of it, like a racing car at a corner. Here are some examples of easing:

Extreme Positions

If you imagine a swinging pendulum, the moment before it changes direction - that’s the extreme position. It’s as far as that pendulum is going to swing and this is where an animator would choose to put a keyframe.

Forward Kinematics (FK)

When animators are creating movement like a swinging arm they’ll often use forward kinematics, it uses joint chains just like the bones in your arm. Starting at the top of the chain (your shoulder) and then working its way down to the bottom (your wrist) these rotations result in the whole arm swinging. By timing the rotations differently for each joint they are able to create effects like a whipping motion or swinging tail. This movement always starts at the top of the chain, for movements that start at the bottom of the chain see “Inverse Kinematics”

Frames

A frame is a single image in a sequence, on TV and in a lot of online content in the UK we see 25 of them every second and this gives the illusion of movement. Animators use frames to measure time, with fewer frames equalling faster movement they can calculate how long a shot will need to move at the right speed. 

Fresnel (pronounced with a silent S)

If you stick fresnel into Google you’ll quickly learn about it’s usage in lighting and how the ridges on the outer side of glass helps focus light beams - clever stuff. When animators talk about it though it’s more likely to be about the fresnel effect. This is an effect where the angle that you view a surface affects how reflective it seems, often with the outer curved surfaces being more reflective than the ones facing you. This will result in highlights appearing around the edges of an object and is a great effect for adding realism and making an object stand out.

Graph editor
Graphs are essential to computer animation. When an animator creates keyframes, the changes between these keyframes get plotted into graphs. There are graphs for all sorts of things like movement, rotation, size, transparency, colour and the graph editor lets the animator see these curves to make sure that fast changes get sharp angles and smooth ones get smooth curves.

Inbetweens

These frames are the poor siblings that bridge the gap between our keyframes. After the keyframes have been set, these are the frames that an animator trusts to a computer and graph editor.

Inverse Kinematics (IK)

Just like forward kinematics, but the other way around. Inverse kinematics takes a joint chain like a leg and gives the animator a control to move the foot and hip. This is particularly useful when you want a foot to stay put when hips move, or vise versa. In an IK joint chain the middle joint rotations are calculated by the computer. So for leg animation we don’t need to worry about bending the knee, the computer takes care of that.

Keyframes

Keyframes (or key poses) mark significant points in an animation when positions and poses need to be in the right place at the right time. The frames in between these are (funnily enough) called “in betweens” and see an object or character travel between keyframes. 

Layers

Layers is a term used to describe elements of an animation layed on top of each other. In 2D animation the “top layer” is the one above everything else and the “bottom layer” is the one behind everything else, usually the background. In 3D animation where front and back aren’t as easily defined because we can navigate a scene from any angle, layers are used as ways to collect groups of objects and control their visibility collectively.

Parenting
It may sound like you’re being given advice on how to raise children but this is a well used technique to make things move together. By parenting a hat to a character's head, you can animate the head and the hat stays put. This halves the workload and gives the animator the opportunity to make all kinds of clever things happen.

Passes
We’re not talking golden tickets to chocolate factories or the key to getting backstage at a gig. Passes or “render passes” are how 3D software separates an image into specified elements like reflections, colour, shadows, highlights and hair. This gives the compositor flexibility to fine-tune how the animation looks.

‍Paths

When animators mention paths they’re talking about predefined routes, usually created from curves for animation to follow. Path animation is an excellent way for text to animate around an object following a curve or for a car to drive around a track. Paths can also be the outlines of shapes and illustrations, something that a computer would use to draw that object.

‍Pose to Pose animation

This type of animation lends itself well to computer animation where we can jump backwards and forwards in time creating poses, moments or “key frames” that act as the underlying foundation of our movement. This is a flexible way to animate and can be blocked out quickly and then finished with extra keyframes. Without care though, it can run the risk of feeling predictable, mechanical and soul-less - that’s why we bring straight-ahead animation into the mix too!

Secondary Movement
When one movement creates another, like ripples on a pond - these are secondary movements. It could be a ponytail bouncing around when someone jumps or a wobbly aerial when a car stops. These extra movements add weight and make animation feel more real.

‍Squash and Stretch

This principle of animation allows an animator to break the laws of physics and exaggerate movement to give it mass and a rubber like quality. If you watch a super slow motion video (and I recommend you do), you’ll notice that all sorts of objects that you’d consider to be “solid” actually squash and stretch upon impact.

Straight ahead animation
We’re not talking straight lines here, despite its name the product of straight ahead animation is a lot more organic. This is where an animator starts at the beginning and ends at the end, improvising as they go along, it creates fluid and spontaneous even unpredictable movements but is great fun to animate. This type of animation is almost unavoidable in physical animation techniques like stop-motion.

Subsurface Scatter
If you’ve ever held a torch behind your fingers you’ll know that you get a really cool red glow with your veins being more visible too. Try it, it’s fun. What’s happening here is the light refracting past the subdermal layers of your hand and is letting you see what’s beneath the skin. When animators talk about subsurface scattering or “SSS” if they’re trying to impress you then this is the effect they’re hoping to achieve.

Walk Cycle
When animators bring characters to life by making them walk they are able to loop or cycle keyframes to save themselves from repeating the same process over and over again. Walking is no exception to this and a walk cycle is a loopable animation with the same position at the start and the end. Typically it would start with one foot forward and end with that same foot forward after taking 2 steps (one with each foot).